SYSTEMS AND METHODS OF MOTION CONTROL IN SEMICONDUCTOR MANUFACTURING EQUIPMENT

Abstract

The motion control system is described. The motion control system comprises a release coupling attached to the fine and rough positioning tables. The release coupling is configured to mechanically coupling the fine positioning table to the rough positioning table during rough positioning movements to transmit motion force from the rough positioning table to the fine positioning table, and to mechanically release the fine positioning table from the rough positioning table in a processing operation such that the fine positioning table is mechanically and dynamically separated from the rough positioning table. This release facilitates precise movements of the fine positioning table. Mechanical coupling of the fine positioning table to the rough positioning table during rough positioning movements facilitates a reduction in the mass, volume, and / or energy consumption required of the fine positioning table actuators, as these actuators only need to control the constant velocity movement of the fine positioning table over a relatively shorter travel distance.

Description

SYSTEMS AND METHODS FOR MOTION CONTROL IN A SEMICONDUCTOR MANUFACTURING APPARATUSCROSS-REFERENCE TO RELATED APPLICATION

[0001] The application claims priority of US application 63 / 546,348 which was filed on 30 October, 2023; and which is incorporated herein in their entirety by reference.TECHNICAL FIELD

[0002] The description herein relates generally to systems and methods for motion control in a semiconductor manufacturing apparatus.BACKGROUND

[0003] A lithographic projection apparatus can be used, for example, in the manufacture of integrated circuits (ICs). A patterning device (e.g., a mask) may include 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 includes 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.

[0004] This 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, deposition, etc. Lithography is a central 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.

[0005] Smaller and smaller features are being patterned onto substrates. In general, the smaller thefeatures, 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 are 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, or other methods generally defined as “resolution enhancement techniques” (RET).

[0006] Patterning with a lithographic projection apparatus, and associated metrology, are integral parts of semiconductor manufacturing which require precision control of various moving components.SUMMARY

[0007] A motion control system for a semiconductor manufacturing apparatus is described. The semiconductor manufacturing apparatus may include a lithography apparatus, a metrology system, and / or other semiconductor manufacturing apparatuses, for example. The motion control system includes a releasable coupling coupled to a fine positioning stage and a coarse positioning stage of the semiconductor manufacturing apparatus. The releasable coupling is configured to switch between coupled and released configurations. The releasable coupling is configured to mechanically couple the fine positioning stage to the coarse positioning stage during coarse positioning movements (e.g., the acceleration and / or deceleration phases of these movements) to transfer movement force from the coarse positioning stage to the fine positioning stage, and mechanically release the fine positioning stage from the coarse positioning stage during a processing operation such that the fine positioning stage is mechanically and dynamically decoupled from the coarse positioning stage. Mechanically releasing comprises no longer transferring pushing or pulling forces between the stages (even though the releasable coupling may or may not remain in physical contact with each stage after a mechanical release, as described below). This release facilitates precision movements of the fine positioning stage. In addition, mechanically coupling the fine positioning stage to the coarse positioning stage during coarse positioning movements facilitates reducing a required mass, volume, and / or energy consumption of one or more fine positioning stage actuators, because these actuators need only control the constant velocity movement of the fine positioning stage. Control of the fine positioning stage may compensate for external disturbance forces, for example. In some embodiments, short stroke actuators only have to compensate such that any disturbance force is much less than the force required to accelerate the fine positioning stage.

[0008] According to an embodiment, a motion control system for a semiconductor manufacturing apparatus is provided. The motion control system comprises an object holder configured to hold an object. The motion control system comprises a fine positioning stage with a first actuator configuredto cause the object holder to move with relatively shorter strokes. The motion control system comprises a coarse positioning stage with a second actuator configured to move with relatively longer strokes in comparison with the fine positioning stage. The motion control system comprises a releasable coupling coupled to the fine positioning stage and the coarse positioning stage. The releasable coupling is configured to switch between coupled and released configurations. The releasable coupling is configured to mechanically couple the fine positioning stage to the coarse positioning stage in the coupled configuration during coarse positioning movements of the coarse positioning stage by the second actuator to transfer movement force from the coarse positioning stage to the fine positioning stage. The releasable coupling is configured to mechanically release the fine positioning stage from the coarse positioning stage in the released configuration during a processing operation such that the fine positioning stage is mechanically and dynamically decoupled from the coarse positioning stage, facilitating precision movements of the fine positioning stage.

[0009] In some embodiments, the semiconductor manufacturing apparatus comprises a lithography apparatus, and the processing operation comprises an exposure of a semiconductor wafer. In some embodiments, the coarse positioning stage, the fine positioning stage, and the object holder together comprise a portion of a semiconductor lithography apparatus, an optical metrology inspection tool, or an e-beam inspection tool. In some embodiments, the object holder comprises a reticle stage chuck or a wafer stage chuck of a semiconductor lithography apparatus, the object comprises a reticle or a semiconductor wafer, movement of the coarse positioning stage by the second actuator with relatively longer strokes in comparison with the fine positioning stage comprises acceleration or deceleration of the coarse positioning stage, and movement of the fine positioning stage by the first actuator with relatively shorter strokes in comparison with the coarse positioning stage comprises movement associated with a scan in the semiconductor lithography apparatus.

[0010] In some embodiments, the coupling is configured to provide a constraining force through physical mechanical contact with a pushing or pulling member of the coupling under compression or tension.

[0011] In some embodiments, the coupling has a first side coupled to the fine positioning stage and a second side coupled to the coarse positioning stage. The coupling is configured to transfer the movement force in a movement direction between the fine positioning stage and the coarse positioning stage. In some embodiments, the movement direction is a scanning direction of the motion control system.

[0012] In some embodiments, the coupling comprises a variable stiffener configured to gradually increase in stiffness as a function of an amount of the movement force. In some embodiments, the coupling is configured to provide a variable stiffness as a mechanical push-pull stiffness in the movement direction. In some embodiments, the coupling is configured to provide the variable stiffness as the mechanical push-pull stiffness in the movement direction only.

[0013] In some embodiments, the variable stiffener comprises one or more variable stiffener actuators, and the stiffness is dependent on a preloading of the one or more variable stiffener actuators. In some embodiments, the variable stiffener comprises viscoelastic material.

[0014] In some embodiments, the coupling (the variable stiffener) and the first actuator of the fine positioning stage are arranged in parallel in between the fine positioning stage and the coarse positioning stage. In some embodiments, the variable stiffener comprises a first portion on a first side of the object holder and / or the fine positioning stage, and a second portion on a second side of the object holder and / or the fine positioning stage.

[0015] In some embodiments, the coupling comprises one or more active pushers configured to contact and push against the fine positioning stage during the coarse positioning movements of the coarse positioning stage. The one or more active pushers are configured to release the fine positioning stage during relatively shorter stroke movements of the fine positioning stage.

[0016] In some embodiments, each active pusher comprises a pusher actuator coupled to a pushing member. The pusher actuator is configured to cause the pushing member to push against and release the fine positioning stage. In some embodiments, the pusher actuator comprises a piezoelectric actuator. In some embodiments, the pusher actuator comprises a Lorentz actuator. In some embodiments, the pusher actuator comprises a magnetostrictive actuator. In some embodiments, the pushing member comprises a rod or a spring.

[0017] In some embodiments, the one or more active pushers comprise two active pushers, with a first active pusher on a first side of the object holder and / or the fine positioning stage between the coarse positioning stage and the first side, and a second active pusher on a second side of the object holder and / or the fine positioning stage between the coarse positioning stage and the second side.

[0018] In some embodiments, the coupling comprises one or more lines configured to: be taught during coarse positioning movements of the coarse positioning stage by the second actuator to transfer the movement force from the coarse positioning stage to the fine positioning stage, and slacken to mechanically release the fine positioning stage from the coarse positioning stage during fine positioning movements of the fine positioning stage by the first actuator such that the fine positioning stage is allowed to move with respect to the coarse positioning stage.

[0019] In some embodiments, the one or more lines comprise one or more wires, ropes, fibers, flexures, sheets, or cables. In some embodiments, the one or more lines comprise at least a first line on a first side of the object holder and / or the fine positioning stage, and at least a second line on a second side of the object holder and / or the fine positioning stage. In some embodiments, the one or more lines are arranged along a movement direction of the coarse positioning stage.

[0020] In some embodiments, the coupling comprises one or more tensioners associated with each of the one or more lines. The one or more tensioners are each configured to tension an associated line such that the line is taught during the coarse positioning movements.

[0021] In some embodiments, a stiffness of the coupling in a movement direction during the coarse positioning movements is at least two orders of magnitude higher than a stiffness of the coupling in other directions and / or a stiffness of the coupling in any direction during the fine positioning movements. In some embodiments, the stiffness of the coupling in the other directions, and / or the stiffness of the coupling during the fine positioning movements is negligible.

[0022] In some embodiments, the first actuator comprises one or more reluctance actuators and / or Lorentz actuators configured to move the fine positioning stage with relatively shorter stroke constant velocity movements. Mechanically coupling the fine positioning stage to the coarse positioning stage during coarse positioning movements of the coarse positioning stage by the second actuator facilitates reducing a required mass, volume, and / or energy consumption of the one or more reluctance actuators because the one or more reluctance actuators need only control the relatively shorter stroke constant velocity movement.

[0023] According to another embodiment, a motion control method is provided. The method is performed by the motion control system, and includes one or more of the operations described above.BRIEF DESCRIPTION OF THE DRAWINGS

[0024] 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.

[0025] Fig. 1 schematically depicts a lithography apparatus, according to an embodiment.

[0026] Fig. 2 schematically depicts an embodiment of a lithographic cell or cluster, according to an embodiment.

[0027] Fig. 3 A illustrates a lithographic apparatus including a reticle handler turret gripper, reticle stage reticle clamps, and / or other components, according to an embodiment.

[0028] Fig. 3B is an enlarged view of a portion of the lithographic apparatus shown in Fig. 3A, according to an embodiment.

[0029] Fig. 4 illustrates (in top or bottom view) a motion control system for a semiconductor manufacturing apparatus, according to an embodiment.

[0030] Fig. 5 illustrates (in side view) an embodiment of a releasable coupling of the motion control system where a pushing or pulling member comprises one or more active pushers (two in this example), according to an embodiment.

[0031] Fig. 6 illustrates (in side view) another embodiment of the releasable coupling where the pushing or pulling member comprises one or more variable stiffeners, according to an embodiment.

[0032] Fig. 7 illustrates (in top or bottom view) embodiments of the releasable coupling where thepushing or pulling member comprises one or more lines, according to an embodiment.

[0033] Fig. 8 illustrates a motion control method, according to an embodiment.

[0034] Fig. 9 is a block diagram of an example computer system, according to an embodiment.DETAILED DESCRIPTION

[0035] In general, an object such as a mask or reticle (e.g., a patterning device) 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. Clamps (e.g., reticle stage reticle clamps) in the lithographic apparatus are used to secure the masks or reticles during processing. The clamps accelerate and drive the reticle in a lithographic apparatus scan direction during processing.

[0036] Throughput (e.g., in wafers per hour in a semiconductor manufacturing context) is determined by both the velocity of the stages during exposure of the mask at constant speed, and the time between exposures, which is accelerating and decelerating to and from this speed. Accelerating requires Force = mass* acceleration, hence actuator size and energy usage is determined by the acceleration requirements. Increased throughput reduces manufacturing costs (e.g., costs per wafer), reduces energy consumption (e.g., energy consumption per wafer or efficiency), and / or has other positive effects. Increasing movement speed, and in turn throughput, in current and future manufacturing systems typically requires larger and larger volume, heavier (more massive), and more energy consuming actuators for short and / or coarse positioning stage movements in such systems - sometimes up to tripling a required actuator mass, for example.

[0037] Advantageously, the present systems and methods provide a motion control system for a semiconductor manufacturing apparatus with a releasable coupling. The releasable coupling is coupled to a fine positioning stage and a coarse positioning stage of the semiconductor manufacturing apparatus. The releasable coupling is configured to mechanically couple the fine positioning stage to the coarse positioning stage during coarse positioning movements to transfer movement force from the coarse positioning stage to the fine positioning stage, and mechanically release the fine positioning stage from the coarse positioning stage during a processing operation (e.g., exposure of the mask to a substrate / wafer, during an imaging operation for metrology, etc.) such that the fine positioning stage is mechanically and dynamically decoupled from the coarse positioning stage. Mechanically coupling the fine positioning stage to the coarse positioning stage during coarse positioning movements facilitates reducing a required mass, volume, and / or energy consumption of one or more fine positioning stage actuators, because these actuators need only control and / or counteract disturbing motions and / or forces from, for example, the coarse positioning stage, the environment, the releasable coupling, etc., to facilitate precision motion of the fine positioning stage.

[0038] For example, during acceleration and deceleration, the releasable coupling is configured suchthat the fine positioning stage is locked to the coarse positioning stage, and the coarse positioning stage pushes and pulls the fine positioning stage. As a result, the fine positioning stage actuators only need to control the fine positioning stage during an operation such as scan (for example) with constant velocity and can be made much less powerful than they would otherwise need to be, with up to an estimated 75% mass reduction. Since the mass of the fine positioning stage actuators is reduced, the coarse positioning stage actuators can also be less powerful, resulting in a further mass reduction.

[0039] The semiconductor manufacturing apparatus may include a lithography apparatus, a metrology system, and / or other semiconductor manufacturing apparatuses, for example. Similar examples are contemplated for metrology systems and / or other semiconductor manufacturing apparatuses.

[0040] 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.”

[0041] As an introduction, prior to transferring a pattern from a patterning device such as a reticle or mask to a substrate such as a semiconductor wafer, 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. The individual devices can be mounted on a carrier, connected to pins, etc.

[0042] 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 separatedinto 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.

[0043] 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.

[0044] 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).

[0045] 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 = k I x / JNA, where X 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.

[0046] Fig. 1 schematically depicts an embodiment of a lithographic apparatus LA that may include and / or be 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. UV radiation, DUV radiation, or EUV radiation); a support structure (e.g. a mask table) MT or object holder constructed to support an object such as a patterning device (e.g. a mask) MA and connected to a first positioner PM configured to accurately position the patterning device in accordance with certain parameters; another object holder such as 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 thesubstrate 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).

[0047] 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.

[0048] 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.

[0049] The illuminator IL may comprise adjuster AD configured to adjust the (angular I spatial) intensity distribution of the beam. Generally, at least the outer and / or inner radial extent (commonly referred to as a-outer and a-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.

[0050] 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 theradiation 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.

[0051] 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.

[0052] 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. In general, the support structure may use 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.

[0053] 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.

[0054] A patterning device may generally be transmissive or reflective, though transmissivepatterning devices are the focus of this particular application. Examples of patterning devices include masks (or reticles), programmable mirror arrays, and programmable LCD panels. Masks are well known in lithography, and include mask types such as binary, alternating phase-shift, and attenuated phaseshift, 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.

[0055] 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 coordinate 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.

[0056] 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.

[0057] 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 betweenthe 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.

[0058] 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, and is patterned by the patterning device. 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 stage or module (coarse positioning) and a short-stroke stage or module (fine positioning), which form part of the first positioner PM. Similarly, movement of the substrate table WT may be realized using a long-stroke stage or module and a short-stroke stage or module, 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 short-stroke actuator 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.

[0059] The depicted apparatus may be used in at least one of the following modes: 1. 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. 2. 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-) magnificationand 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 scan mode, the velocity may be non-constant. 3. 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 above-described modes of use or entirely different modes of use may also be employed.

[0060] 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.

[0061] 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.

[0062] 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. These patterns can be referred to as “hot spots” or “process window limiting patterns (PWLPs),” which are used interchangeably herein. When controlling a part of a patterning process, it is possible and economical to focus on the hot spots. When the hot spots are not defective, it is most likely that other patterns are not defective.

[0063] 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- andpost-exposure 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.

[0064] 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 (MS) 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)).

[0065] 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.

[0066] 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 abeam 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 bedetermined. 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 +lstorders in the diffraction spectrum of a periodic grating). Another application of diffractionbased metrology is in the measurement of feature width (CD) within a target.

[0067] 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)).

[0068] 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.

[0069] 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.

[0070] 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 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., intoone or more layers on the substrate).

[0071] 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.

[0072] The present systems, and / or methods may be used as stand-alone tools and / or techniques, and / or or used in conjunction with other semiconductor manufacturing processes, to enhance the accurate transfer of complex designs to physical wafers. The present motion control system comprises a holder, a fine positioning stage, a coarse positioning stage, a releasable coupling, and / or other components configured to hold and move an object such as a patterning device (e.g., a reticle or mask), a substrate such as a semiconductor wafer, and / or other objects. The present systems and / or methods may be associated with an extreme ultraviolet (EUV) lithography apparatus, a deep ultraviolet (DUV) lithography apparatus, a metrology system, and / or other semiconductor manufacturing equipment, for example.

[0073] By way of a non-limiting example, Fig. 3A and 3B illustrate (a portion of) a lithographic apparatus 300 (e.g., similar to an or the same as the lithographic apparatus shown in Fig. 1). Lithographic apparatus 300 may use a patterning device such as a reticle to pattern a substrate such as a semiconductor wafer to form semiconductor devices. Fig. 3A illustrates various components of lithographic apparatus 300 including a tool handler 306, 307, 308, reticle stage 310 and reticle clamps 312 (only one side is visible in Fig. 3 A) which form a portion of an embodiment 302 of the present motion control system, and / or other components. In some embodiments, lithographic apparatus 300 is configured for deep ultraviolet (DUV) lithography. In some embodiments, a similar apparatus may be configured for extreme ultraviolet (EUV) lithography. In some embodiments, motion control system embodiment 302 comprises a reticle stage 310, reticle clamps 312, actuator(s), or more processors and / or computing system described herein (see Fig. 9), one or more sensors, and / or other components.

[0074] In some embodiments, tool handler 306, 307, 308 comprises a reticle handler turret gripper 306, a reticle handler robot gripper 307 (having associated clamps 308, etc. for gripping a reticle), 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 clamps 312. Lithographic 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 a reticle through lithographic apparatus 300.

[0075] Fig. 3B is an enlarged view of a portion of lithographic apparatus 300. Fig. 3B shows motion control system embodiment 302, reticle handler turret gripper 306, reticle stage 310, reticle stage reticle clamps 312 (only one side is visible in Fig. 3B), mechanical components 322, reticle handler robotgripper 307, and / or other components. As shown in Fig. 3B, reticle handler turret gripper 306 is configured to move a reticle from reticle handler robot gripper 307 to reticle clamps 312 so motion control system embodiment 302 can be used to clamp and move the reticle. Reticle handler turret gripper 306 and / or reticle handler robot gripper 307 may include various motors, translators, rotational components, clamps, clips, power sources, power transmission components, vacuum mechanisms, and / or other components that facilitate the movement of a reticle.

[0076] Fig. 4 illustrates a more detailed view (e.g., a top view or a bottom view) of an embodiment 400 of a motion control system 499. Embodiment 400 may be similar to and / or the same as embodiment 302, for example. In some embodiments, embodiment 400 may be configured for an EUV related lithography apparatus, instead of a DUV related system like lithographic apparatus 300, and / or have other configurations. (However, embodiment 400 may also be used in a DUV apparatus.) Embodiment 400 comprises an object holder 402, a fine positioning stage 406 with a first actuator 408 (or actuators), a coarse positioning stage 410 with a second actuator 412 (or actuators), a releasable coupling 420, and / or other components. In some embodiments, one or more components of the motion control system 499 (e.g., embodiment 302 shown in Fig. 3A and 3B and / or embodiment 400 shown in Fig. 4) includes and / or is configured to communicate with one or more processors and / or a computing system, as described below (see Fig. 9). In some embodiments, one or more portions of the motion control system 499 may be 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. 9 below).

[0077] Object holder 402 is configured to hold an object 401. In some embodiments, for example, object holder 402 comprises a stage in a semiconductor lithography apparatus (e.g., LA shown in Fig. 1, apparatus 300 shown in Fig. 3 A and 3B, etc.), an optical metrology inspection tool (e.g., metrology system MS shown in Fig. 2), or an e-beam inspection tool, and / or other objects. In some embodiments, object holder 402 may comprise a reticle stage chuck or a wafer stage chuck of a lithography apparatus, a wafer stage and / or other holder in a metrology system, and / or other object holders. Object 401 may comprise a patterning device such as a reticle, a semiconductor wafer, and / or other objects, for example. In some embodiments, one or more of the stages, holders, and / or chucks described above may be associated with a lithography apparatus configured for DUV or EUV radiation.

[0078] In the example shown in Fig. 4, object 401 is a reticle (e.g., similar to and / or the same as the reticles and / or patterning devices described above). In some embodiments, a reticle has a rectangular shape. For simplicity and to facilitate the discussion herein, a reticle may be thought of as a single block of material shaped as a rectangular prism. In some embodiments, some or all of a reticle 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, aceramic, and / or other materials. Fabrication of a reticle can utilize any number of materials.

[0079] In the example shown in Fig. 4, object holder 402 is a reticle stage chuck in a semiconductor lithography apparatus. A reticle stage chuck is used in combination with clamps and / or other components in a lithographic apparatus to secure a patterning device or reticle during processing. In some embodiments, the motion control system 499 includes and / or is configured to communicate with one or more sensors, one or more processors and / or a computing system as described below (see Fig. 9), and / or other components. The various components of the system may be coupled in any arrangement and using any coupling components that allow the system to function as described herein.

[0080] Fine positioning stage 406 with first actuator 408 is configured to cause object holder 402 to move. Fine positioning stage 406 is configured to cause object holder 402 to move with relatively shorter strokes in comparison to movement caused by coarse positioning stage 410. In some embodiments, first actuator 408 comprises one or more reluctance actuators and / or Lorentz actuators configured to move fine positioning stage 406 with relatively shorter stroke constant velocity movements, for example. Using magnetic reluctance or resistance, a reluctance actuator causes nonpermanent 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. This reluctance force is only attractive, never repulsive. A Lorentz actuator is an electronic actuator with a piston coupled to a (usually) copper coil and a magnet that produces an actuation force to move the piston. A Lorentz actuator is an electric actuator with a current carrying conductor placed in an external magnetic field. Vector components of the external magnetic field perpendicular to the current direction cause a Lorentz force on the moving charges in the wire in a direction perpendicular to both the current direction and external magnetic field direction. The force imparted on the charges is then imparted to the current carrying conductor. An equal and opposite reaction force is imparted on external magnetic field source, enabling a change in relative motion between the source and the conductor when the current carrying conductor is excited. In a Lorentz actuator, directional control is made possible by changing the relative direction of the current and the external magnetic field.

[0081] Coarse positioning stage 410, with second actuator 412, is configured to move with relatively longer strokes in comparison with the fine positioning stage. In some embodiments, second actuator 412 comprises one or more linear actuators, for example linear synchronous machines of various types (e.g. linear permanent magnet synchronous machines with / without ferromagnetic cores, linear reluctance synchronous machines, linear inductance motors, etc.), and / or other actuators. In some embodiments, movement of coarse positioning stage 410 by (second) actuator 412 with relatively longerstrokes in comparison with the fine positioning stage comprises acceleration or deceleration of coarse positioning stage 410. This acceleration and / or deceleration may be used to move coarse positioning stage 410, fine positioning stage 406, object holder 402, object 401, and / or other components in relatively large and rapid movements to an approximate location for processing. Once in the approximate location for processing, movement of fine positioning stage 406 by first actuator 408 with relatively shorter strokes in comparison with coarse positioning stage 410 occurs. This movement may comprise movement associated with a scan in the semiconductor lithography apparatus, for example (see Fig. 1, Fig. 3 A, 3B), and / or other movements.

[0082] Releasable coupling 420 is coupled to fine positioning stage 406 and coarse positioning stage 410. Releasable coupling 420 is illustrated in two locations in Fig. 4, with one location on one side of fine positioning stage 406, and another location on the opposite side of fine positioning stage 406. However, this is not intended to be limiting. One, two, three, four, or more instances of coupling 420 may be included in embodiment 400 of the motion control, in any location(s) that allow the motion control system 499 to function as described herein.

[0083] Releasable coupling 420 is configured to switch between coupled and released configurations. Releasable coupling 420 is configured to mechanically couple fine positioning stage 406 to coarse positioning stage 410 (in the coupled configuration) during coarse positioning movements of coarse positioning stage 410. The coupled configuration is configured to transfer movement force from coarse positioning stage 410 to fine positioning stage 406. Releasable coupling 420 is also configured to mechanically release fine positioning stage 406 from coarse positioning stage 410 (in the released configuration) during a processing operation. The processing operation may be a scan or an exposure of a semiconductor wafer, a metrology operation, and / or other processing operations, for example. The released configuration is configured such that fine positioning stage 406 is mechanically and dynamically decoupled from coarse positioning stage 410 during the processing operation.

[0084] The released configuration facilitates precision movements of fine positioning stage 406 during the processing operation, for example. Mechanically coupling fine positioning stage 406 to coarse positioning stage 410 during coarse positioning movements of coarse positioning stage 410 facilitates reducing a required mass, volume, and / or energy consumption of the one or more reluctance actuators because the one or more reluctance actuators need only control the short stroke constant velocity movement, for example, as described above.

[0085] In some embodiments, coupling 420 is configured to provide a constraining force through physical mechanical contact with a pushing or pulling member 422 of coupling 420 under compression or tension. In some embodiments, coupling 420 is configured to provide the constraining force and / or a mechanical push-pull stiffness in a movement (or driving) direction 430. In some embodiments, coupling 420 is configured to provide at least some constraining force and / or stiffness in non-movement (e.g., perpendicular and / or other) directions. For example, in some embodiments, coupling 420 has afirst side A coupled to fine positioning stage 406 and a second side B coupled to coarse positioning stage 410. Coupling 420 is configured to transfer the movement force in movement direction 430 between fine positioning stage 406 and coarse positioning stage 410. In some embodiments, movement direction 430 is a scanning direction of the motion control system 499, for example.

[0086] In some embodiments, a constraining force and / or stiffness of coupling 420 in movement direction 430 during the coarse positioning movements is at least two orders of magnitude higher than a constraining force and / or stiffness of coupling 420 in other directions and / or a constraining force and / or stiffness of coupling 420 in any direction during the fine positioning movements. In some embodiments, the constraining force and / or stiffness of coupling 420 in the other directions, and / or the constraining force and / or stiffness of coupling 420 during the fine positioning movements is negligible. However, as described below, in some embodiments, coupling 420 is capable of providing at least some constraining force and / or stiffness in non-movement directions during coarse positioning and / or fine positioning movements.

[0087] In some embodiments, coupling 420 comprises a variable stiffener configured to gradually increase in stiffness as a function of an amount of the movement force. In some embodiments, coupling 420 is configured to provide a variable stiffness as a mechanical push-pull stiffness in the movement (or driving) direction 430. In some embodiments, coupling 420 is configured to provide the variable stiffness as the mechanical push-pull stiffness in movement direction 430 and / or non-movement directions during coarse positioning movements of coarse positioning stage 410 (and little to no stiffness during fine positioning movements of fine positioning stage 406). In some embodiments, coupling 420 is configured to provide the variable stiffness as the mechanical push-pull stiffness in movement direction 430 only (and only during coarse positioning movements).

[0088] Various embodiments of coupling 420 including the features described above and / or other features are shown in Fig. 5-7 and described below. Note that these are representative examples of many other possible embodiments that may be configured to function as described here.

[0089] For example, Fig. 5 illustrates (in side view) an embodiment 500 of coupling 420 where pushing or pulling member 422 comprises one or more active pushers 502 (two in this example). Embodiment 500 may provide relatively high constraining force and / or stiffness in movement direction 430 and in non-movement directions in the coupled configuration, and zero or nearly zero constraining force and / or stiffness in any direction in the released configuration.

[0090] Active pushers 502 are illustrated in two locations in Fig. 5, with one location on one side of fine positioning stage 406, and another location on the opposite side of fine positioning stage 406. However, this is not intended to be limiting. One, two, three, four, or more instances of active pushers may be included in the motion control system 499 (e.g., embodiment 400 shown in Fig. 4), in any location(s) that allow the motion control system 499 to function as described herein. For example, in some embodiments, only one active pusher 502 on one side of fine positioning stage 406 may be needed.

[0091] Active pushers 502 are configured to contact and push against fine positioning stage 406 during the coarse positioning movements of coarse positioning stage 410. The one or more active pushers 502 are configured to release fine positioning stage 406 (e.g., as shown in Fig. 5) during relatively shorter stroke movements of fine positioning stage 406. For example, the one or more active pushers 502 may be released and / or otherwise decoupled during a scanning operation, such that there are little to no disturbance forces on fine positioning stage 406 from other components of a lithographic apparatus (see Fig. 1, 3A, 3B).

[0092] In some embodiments, each active pusher 502 comprises a pusher actuator 510 coupled to a pushing member 512. Each pusher actuator 510 is configured to cause a pushing member 512 to push against and release fine positioning stage 406. In some embodiments, a pusher actuator 510 comprises a piezoelectric actuator. In some embodiments, a pusher actuator 510 comprises a Lorentz actuator. In some embodiments, a pusher actuator 510 comprises a magnetostrictive actuator (or sometimes termed a magneto-restrictive actuator). Other types of actuators are also contemplated. In some embodiments, a pushing member 512 comprises a rod or a spring and / or other components.

[0093] In some embodiments, the one or more active pushers 502 comprise two (or more) active pushers. Fig. 5 illustrates one active pusher 502 on the left side of fine positioning stage 406, and a second active pusher 502 on the right side of fine positioning stage 406. A first active pusher 502 may be located on a first side 550 of the object holder and / or fine positioning stage 406 between coarse positioning stage 410 and first side 550, on the left side in Fig. 5 for example. A second active pusher 502 may be located on a second side 555 of the object holder and / or fine positioning stage 406 between coarse positioning stage 410 and second side 555, on the right side in Fig. 5 for example. Other configurations with more or less active pushers 502 are contemplated.

[0094] As another example, Fig. 6 illustrates (in side view) an embodiment 600 of coupling 420 where pushing or pulling member 422 comprises one or more variable stiffeners 602. Embodiment 600 may provide relatively high constraining force and / or stiffness in movement direction 430 and in nonmovement directions in the coupled configuration, and relatively low (but non- zero) constraining force and / or stiffness in any direction in the released configuration. Fig. 6 illustrates coarse positioning stage 410, fine positioning stage 406 (with a chuck 650 and a clamp 655 in this example), fine positioning stage 406 (first) actuators 408, and other components. In this example, (first) actuators 408 comprise reluctance actuators. In Fig. 6, a variable stiffener 602 is illustrated, with variable stiffener 602 shown on one side of fine positioning stage 406. However, this is not intended to be limiting. Multiple instances of variable stiffener 602 may be included in the motion control system 499 (e.g., embodiment 400 shown in Fig. 4), and / or the functionality of a single variable stiffener may be divided between any number of location(s) that allow the motion control system 499 to function as described herein. For example, in some embodiments, variable stiffener 602 comprises a first portion on a first side of the object holder (e.g., 402 in Fig. 4) and / or fine positioning stage 406, and a second portion on a secondside of the object holder and / or fine positioning stage 406. In some embodiments, variable stiffener 602 may function and / or be arranged similar to and / or the same as a coupling comprising a variable stiffener described in international patent application publication no. WO 2023 / 078788 titled “Lithographic Apparatus Stage Coupling”, which is incorporated by reference in its entirety.

[0095] In some embodiments, variable stiffener 602 comprises one or more variable stiffener actuators 610, structural connector members 612, viscoelastic material 614, a housing 616, and / or other components. Housing 616 is configured to house the other components of variable stiffener 602. Structural connector members 612 are configured to connect variable stiffener 602 to fine positioning stage 406 on one side, and coarse positioning stage 410 on the other, so that movement force is transferred from long stroke stage 410 to short stroke stage 406 (Fig. 4) during coarse positioning movements as described herein. Variable stiffener actuators 610 are configured to switch the stiffness by expanding a relatively small amount, thereby pushing visco-elastic material into a (e.g., wedge and / or other shaped) enclosure, which significantly increases the coupling stiffness by using the volumetric stiffness of the viscoelastic body. Viscoelastic material 614 is configured to exhibit elastic (and / or other deformation allowing) characteristics during fine positioning movements of fine positioning stage 406 such that fine positioning stage 406 can move freely (or nearly freely). Viscoelastic material 614 is configured to exhibit viscous (or deformation resistant) characteristics during coarse positioning movements of coarse positioning stage 410 such that movement force is transferred from coarse positioning stage 410 to fine positioning stage 406 as described above. In this way, fine positioning stage 406 can remain coupled to variable stiffener 602 (and in turn coarse positioning stage 410) during a processing operation such as a scan, but with relatively low stiffness.

[0096] In some embodiments, viscoelastic material 614 may comprise rubber formed into a conical shape (as shown in Fig. 6) and / or comprise other materials in other shapes. This configuration may be configured to vary in stiffness by as much as four orders of magnitude, for example from 1E4 N / m (e.g., low enough to mechanically release or decouple fine positioning stage 406 during a processing operation such as a scan) to 1E8 N / m (e.g., high enough to mechanically couple fine positioning stage 406 to coarse positioning stage 410).

[0097] The stiffness of variable stiffener 602 is dependent on a preloading of the one or more variable stiffener actuators 610 and / or other factors (e.g., as described above). In some embodiments, variable stiffener 602 and (first) actuator 408 of fine positioning stage 406 are arranged in parallel in between fine positioning stage 406 and coarse positioning stage 410. In some embodiments, variable stiffener 602 is placed in series with a first actuator (e.g., piezo) (and an internal balance mass). In some embodiments, variable stiffener 602 is placed in parallel so that both (a first actuator and variable stiffener 602) have one side connected to the coarse positioning stage (e.g., 410) and one side connected to the fine positioning stage (e.g., 406). Connection in series means that both actuators have to work, and have to be connected with mechanical stiffness. Advantageously, connection in parallel means thateither one of the actuators can work on the moving body (e.g., a chuck). Therefore, in parallel the active coupling reduces the force (and heat dissipation) of the fine positioning actuator during acceleration with relatively high drive force.

[0098] As yet another example, Fig. 7 illustrates (in top or bottom views) embodiments 700 and 702 of coupling 420 (Fig. 4) where pushing or pulling member 422 (Fig. 4) comprises one or more lines 704. The one or more lines 704 and 704T are configured to be taut during coarse positioning movements of the coarse positioning stage 410 (by the second actuator 412 shown in Fig. 4). A taught line 704T is configured to transfer the movement force from coarse positioning stage 410 to fine positioning stage 406. The one or more lines 704 are configured to slacken to mechanically release fine positioning stage 406 from coarse positioning stage 410 during fine positioning movements of fine positioning stage 406 (by the first actuator(s) 408). This allows fine positioning stage 406 to move substantially freely with respect to coarse positioning stage 410. For example, in embodiment 700, line 704T on the right side is taught because coarse positioning stage 410 is moving to the right in this illustration.

[0099] In some embodiments, the one or more lines 704 and 704T comprise one or more wires, ropes, fibers, flexures, sheets, cables, and / or other lines. In some embodiments, the one or more lines 704 and 704T comprise at least a first line on a first side (e.g., the right side in Fig. 7) of the object holder and / or fine positioning stage 406, and at least a second line on a second side (e.g., the left side in Fig. 7) of the object holder and / or fine positioning stage 406. In some embodiments, the one or more lines 704 and 704T are arranged along a movement direction 430 of coarse positioning stage 410. In this example, lines 704 and 704T are arranged in multiple locations and are generally parallel to movement direction 430.

[0100] In some embodiments, as shown in embodiment 702, releasable coupling 420 comprises one or more tensioners 750 associated with each of the one or more lines 704 and 704T. The one or more tensioners 750 are each configured to tension an associated line 704 and 704T such that the line is taught during the coarse positioning movements. In some embodiments, tensioners 750 may tension an associated line 704 by extending (see arrows on each tensioner 750 in the figure on the right side of Fig. 7, and compare to the left side) one or more components of the tensioner to apply a force to a line, as shown in the left versus right images illustrating embodiment 702 in Fig. 7.

[0101] Embodiment 702 substantially reduces the lag between long stroke stage 410 and short stroke stage 406 by actively controlling the tension of the lines 704, to alternatively couple and release or uncouple short stroke stage 406 motion to the long stroke stage 410 motion on command (without waiting for relative motion to create tension). The wire pre-tensioning can be done by any displacement actuator that moves transversal to the pulling wire, and / or by other mechanisms. It can also be done in the wire direction, directly stretching the wire by a linear actuator. In some embodiments, a wire may be guided over a pully disc, which is rotated to pre-tension the wire. Other mechanisms are contemplated.

[0102] In embodiment 700, the motion of fine positioning stage 406 lags coarse positioning stage 410 motion so that tension can develop. During acceleration (to the right in embodiment 700), coarse positioning stage 410 moves away from fine positioning stage 406 to take up slack in a line 704 so that it becomes a line 704T, before force is applied to fine positioning stage 406 from the movement of coarse positioning stage 410 via line 704T. Embodiment 702 substantially reduces the lag between coarse positioning stage 410 and fine positioning stage 406 by actively controlling the tension of the lines 704, to alternatively couple and release or uncouple fine positioning stage 406 motion to the coarse positioning stage 410 motion on command (without waiting for relative motion to create tension). This may be advantageous for achieving more accurate motion control, and / or increasing the stage throughput, and / or extending the lifetime of the wires, etc. by reducing impact loads, and / or for other reasons.

[0103] Embodiment 700 may provide relatively high constraining force and / or stiffness during coarse positioning acceleration in a left or right direction along movement direction 430, and zero or near zero constraining force and / or stiffness in other directions during acceleration, or in any direction in the released configuration. Embodiment 702 may provide relatively high constraining force and / or stiffness in movement direction 430 and in other directions during coarse positioning acceleration (see the bottom right image in Fig. 7), and zero or near zero constraining force and / or stiffness in any direction in the released configuration (see the bottom left image in Fig. 7). Note that any number of instances of lines 704 and 704T may be included in the motion control system 499 (e.g., embodiment 400 shown in Fig. 4), in any number of location(s) that allow the motion control system 499 to function as described herein.

[0104] Returning to Fig. 4, in some embodiments, the motion control system 499 (e.g., embodiment 400 shown in Fig. 4) comprises one or more processors and / or a computing system, as described below (see Fig. 9). The one or more processors and / or computing system may be operatively coupled to fine positioning stage 406, coarse positioning stage 410, (first) actuators 408 and / or (second) actuators 412, and / or other components. The one or more processors and / or computing system may be configured to provide a feedforward signal to fine positioning stage 406, coarse positioning stage 410, and / or actuators 408 and / or 412 for object holder 402. The feedforward signal may be determined based on a desired setpoint trajectory, based on calibrated and / or calculated corrections, and / or other information. The setpoint trajectory is the movement profile (position / velocity / acceleration / jerk / etc.) that the fine positioning stage 406 should follow. The setpoint trajectory describes the position in time the stage should follow to perform an exposure, for example, as described above, in the context of a scanning mode. A corresponding velocity and acceleration setpoint may be associated with a desired position setpoint. Depending on the physics of a given situation, either one of these trajectories can be used to apply a feed forward signal to improve the tracking of the position setpoint. Corrections may comprise small deviations from this ideal trajectory to correct for imperfections in an exposure (e.g. a heated lensor an external disturbance, etc.). Calibrated / calculated corrections may be needed to deal with imperfections of the stage and / or disturbance forces acting on the stage. This data may be entered and / or selected by a user via a user interface that is part of the computing system (see Fig. 9), determined automatically by the one or more processors, and / or obtained by other methods.

[0105] In some embodiments, the one or more processors and / or one or more sensors may be included in lithographic apparatus LA (Fig. 1) and / or lithographic apparatus 300 (Fig. 3 A, 3B), for example, and / or be associated with control software running on lithographic apparatus LA and / or apparatus 300. The one or more processors are configured by machine-readable instructions. Communication may be wired and / or wireless, for example, as described below (in conjunction with Fig. 9). One or more processors may facilitate receiving entry and / or selection of control commands from the user via a user interface. In some embodiments, the one or more processors may determine the control commands automatically. These control commands may be received in real time or near real time. In some embodiments, the control commands comprise adjustments to a scan movement profile, for example, forces provided by the motion control system 499, feedforward signals, and / or other control commands.

[0106] Fig. 8 illustrates a motion control method 800. Method 800 may be performed with a motion control system, as described above, for example. In some embodiments, the motion control system includes and / or is configured to communicate with one or more processors and / or a computing system, as described below (see Fig. 9). The operations of method 800 presented below are intended to be illustrative. In some embodiments, method 800 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 800 are illustrated in Fig. 8 and described below is not intended to be limiting. For example, one or more of these operations may not occur sequentially in time, but instead in parallel.

[0107] In some embodiments, one or more portions of method 800 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. 9 below). The one or more processing devices may include one or more devices executing some or all of the operations of method 800 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 800 (e.g., see discussion related to Fig. 9 below).

[0108] At an operation 802, an object may be held with an object holder. In some embodiments, the object holder comprises a stage in a semiconductor lithography apparatus, an optical metrology inspection tool, or an e-beam inspection tool, and / or other objects. In some embodiments, the objectholder may comprise a reticle stage chuck or a wafer stage chuck of a lithography apparatus, a wafer stage and / or other holder in a metrology system, and / or other object holders. The object may comprise a patterning device such as a reticle, a semiconductor wafer, and / or other objects, for example. In some embodiments, one or more of the stages, holders, and / or chucks described above may be associated with a lithography apparatus configured for DUV or EUV radiation. In some embodiments, operation 802 is performed by an object holder similar to and / or the same as object holder 402 shown in Fig. 4 and described herein, and / or other components.

[0109] Operation 804 comprises coupling a fine positioning stage with a first actuator to the object holder. The fine positioning stage is configured to cause the object holder to move with relatively shorter strokes. In some embodiments, the first actuator comprises one or more reluctance actuators and / or Lorentz actuators configured to move the fine positioning stage with relatively shorter stroke constant velocity movements, for example. In some embodiments, operation 804 is performed by a fine positioning stage similar to and / or the same as fine positioning stage 406 and (first) actuator 408 shown in Fig. 4 and described herein, and / or other components.

[0110] Operation 806 comprises coupling a coarse positioning stage, with a second actuator configured to move with relatively longer strokes in comparison with the fine positioning stage, to the fine positioning stage. In some embodiments, movement of the coarse positioning stage by the second actuator with relatively longer strokes in comparison with the fine positioning stage comprises acceleration or deceleration of the coarse positioning stage. Movement of the fine positioning stage by the first actuator with relatively shorter strokes in comparison with the coarse positioning stage comprises movement associated with a scan in the semiconductor lithography apparatus, for example. In some embodiments, operation 806 is performed by a coarse positioning stage similar to and / or the same as coarse positioning stage 410 and actuator 412 shown in Fig. 4 and described herein, and / or other components.

[0111] Operation 808 comprises switching a releasable coupling coupled to the fine positioning stage and the coarse positioning stage between coupled and released configurations. The releasable coupling is configured to mechanically couple the fine positioning stage to the coarse positioning stage (in the coupled configuration) during coarse positioning movements of the coarse positioning stage by the second actuator. The coupled configuration is configured to transfer movement force from the coarse positioning stage to the fine positioning stage. The releasable coupling is also configured to mechanically release the fine positioning stage from the coarse positioning stage (in the released configuration) during a processing operation. The processing operation may be an exposure of a semiconductor wafer, a metrology operation, and / or other processing operations. The released configuration is configured such that the fine positioning stage is mechanically and dynamically decoupled from the coarse positioning stage during the processing operation.

[0112] The release facilitates precision movements of the fine positioning stage during theprocessing operation, for example. Mechanically coupling the fine positioning stage to the coarse positioning stage during coarse positioning movements of the coarse positioning stage by the second actuator facilitates reducing a required mass, volume, and / or energy consumption of the one or more reluctance actuators because the one or more reluctance actuators need only control the relatively shorter stroke constant velocity movement, for example.

[0113] In some embodiments, the coupling is configured to provide a constraining force through physical mechanical contact with a pushing or pulling member of the coupling under compression or tension. In some embodiments, the coupling comprises a variable stiffener configured to gradually increase in stiffness as a function of an amount of the movement force. In some embodiments, the coupling is configured to provide a variable stiffness as a mechanical push-pull stiffness in the movement direction. In some embodiments, the coupling is configured to provide the variable stiffness as the mechanical push-pull stiffness in the movement direction only.

[0114] In some embodiments, the coupling has a first side coupled to the fine positioning stage and a second side coupled to the coarse positioning stage. The coupling is configured to transfer the movement force in a movement direction between the fine positioning stage and the coarse positioning stage. In some embodiments, the movement direction is a scanning direction of the motion control system, for example.

[0115] In some embodiments, the variable stiffener comprises one or more variable stiffener actuators, and the stiffness is dependent on a preloading of the one or more variable stiffener actuators. In some embodiments, the variable stiffener comprises viscoelastic material. In some embodiments, the coupling (the variable stiffener) and the first actuator of the fine positioning stage are arranged in parallel in between the fine positioning stage and the coarse positioning stage. In some embodiments, the variable stiffener comprises a first portion on a first side of the object holder and / or the fine positioning stage, and a second portion on a second side of the object holder and / or the fine positioning stage.

[0116] In some embodiments, the coupling comprises one or more active pushers configured to contact and push against the fine positioning stage during the coarse positioning movements of the coarse positioning stage. The one or more active pushers are configured to release the fine positioning stage during relatively shorter stroke movements of the fine positioning stage. In some embodiments, each active pusher comprises a pusher actuator coupled to a pushing member. The pusher actuator is configured to cause the pushing member to push against and release the fine positioning stage. In some embodiments, the pusher actuator comprises a piezoelectric actuator. In some embodiments, the pusher actuator comprises a Lorentz actuator. In some embodiments, the pusher actuator comprises a magnetostrictive actuator. Other types of actuators are also contemplated. In some embodiments, the pushing member comprises a rod or a spring and / or other components.

[0117] In some embodiments, the one or more active pushers comprise two (or more) active pushers.A first active pusher may be located on a first side of the object holder and / or the fine positioning stage between the coarse positioning stage and the first side, for example. A second active pusher may be located on a second side of the object holder and / or the fine positioning stage between the coarse positioning stage and the second side.

[0118] In some embodiments, the coupling comprises one or more lines configured to be taught during coarse positioning movements of the coarse positioning stage (by the second actuator). A taught line is configured to transfer the movement force from the coarse positioning stage to the fine positioning stage. The one or more lines are configured to slacken to mechanically release the fine positioning stage from the coarse positioning stage during fine positioning movements of the fine positioning stage (by the first actuator). This allows the fine positioning stage to move with respect to the coarse positioning stage.

[0119] In some embodiments, the one or more lines comprise one or more wires, ropes, fibers, flexures, sheets, cables, and / or other lines. In some embodiments, the one or more lines comprise at least a first line on a first side of the object holder and / or the fine positioning stage, and at least a second line on a second side of the object holder and / or the fine positioning stage. In some embodiments, the one or more lines are arranged along a movement direction of the coarse positioning stage.

[0120] In some embodiments, the coupling comprises one or more tensioners associated with each of the one or more lines. The one or more tensioners are each configured to tension an associated line such that the line is taught during the coarse positioning movements.

[0121] In some embodiments, a stiffness of the coupling in a movement direction during the coarse positioning movements is at least two orders of magnitude higher than a stiffness of the coupling in other directions and / or a stiffness of the coupling in any direction during the fine positioning movements. In some embodiments, the stiffness of the coupling in the other directions, and / or the stiffness of the coupling during the fine positioning movements is negligible. In some embodiments, operation 808 is performed by a coupling similar to and / or the same as coupling 420 shown in Fig. 4 and described herein, and / or other components.

[0122] Fig. 9 is a block diagram that illustrates a computer system 900 that can assist in implementing the methods, flows, or the system(s) disclosed herein. Computer system 900 includes a bus 902 or other communication mechanism for communicating information, and a processor 904 (or multiple processors 904 and 905) coupled with bus 902 for processing information. Computer system 900 also includes a main memory 906, such as a random access memory (RAM) or other dynamic storage device, coupled to bus 902 for storing information and instructions to be executed by processor 904. Main memory 906 also may be used for storing temporary variables or other intermediate information during execution of instructions to be executed by processor 904. Computer system 900 further includes a read only memory (ROM) 908 or other static storage device coupled to bus 902 for storing static information and instructions for processor 904. A storage device 910, such as a magneticdisk or optical disk, is provided and coupled to bus 902 for storing information and instructions.

[0123] Computer system 900 may be coupled via bus 902 to a display 912, such as a flat panel or touch panel display for displaying information to a computer user. An input device 914, including alphanumeric and other keys, is coupled to bus 902 for communicating information and command selections to processor 904. Another type of user input device is cursor control 916, such as a mouse, a trackball, or cursor direction keys for communicating direction information and command selections to processor 904 and for controlling cursor movement on display 912. 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.

[0124] According to one embodiment, portions of one or more flows and / or methods described herein may be performed by computer system 900 in response to processor 904 executing one or more sequences of one or more instructions contained in main memory 906. Such instructions may be read into main memory 906 from another computer -readable medium, such as storage device 910. Execution of the sequences of instructions contained in main memory 906 causes processor 904 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 906. 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.

[0125] The term “computer-readable medium” or “machine readable medium” as used herein refers to any medium that participates in providing instructions to processor 904 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 910. Volatile media include dynamic memory, such as main memory 906. Transmission media include coaxial cables, copper wire and fiber optics, including the wires that comprise bus 902. 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.

[0126] Various forms of computer readable media may be involved in carrying one or more sequences of one or more instructions to processor 904 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 telephone line using a modem. A modem local to computer system 900 can receive the data on the telephone line and use an infraredtransmitter to convert the data to an infrared signal. An infrared detector coupled to bus 902 can receive the data carried in the infrared signal and place the data on bus 902. Bus 902 carries the data to main memory 906, from which processor 904 retrieves and executes the instructions. The instructions received by main memory 906 may optionally be stored on storage device 910 either before or after execution by processor 904.

[0127] Computer system 900 may also include a communication interface 918 coupled to bus 902. Communication interface 918 provides a two-way data communication coupling to a network link 920 that is connected to a local network 922. For example, communication interface 918 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 918 sends and receives electrical, electromagnetic, or optical signals that carry digital data streams representing various types of information.

[0128] Network link 920 typically provides data communication through one or more networks to other data devices. For example, network link 920 may provide a connection through local network 922 to a host computer 924 or to data equipment operated by an Internet Service Provider (ISP) 926. ISP 926 in turn provides data communication services through the worldwide packet data communication network, now commonly referred to as the “Internet” 928. Local network 922 and Internet 928 both use electrical, electromagnetic, or optical signals that carry digital data streams. The signals through the various networks and the signals on network link 920 and through communication interface 918, which carry the digital data to and from computer system 900, are exemplary forms of carrier waves transporting the information.

[0129] Computer system 900 can send messages and receive data, including program code, through the network(s), network link 920, and communication interface 918. In the Internet example, a server 930 might transmit a requested code for an application program through Internet 928, ISP 926, local network 922 and communication interface 918. One such downloaded application may provide all or part of a method described herein, for example. The received code may be executed by processor 904 as it is received, and / or stored in storage device 910, or other non-volatile storage for later execution. In this manner, computer system 900 may obtain application code in the form of a carrier wave.

[0130] 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 manufacturing apparatus, comprising: an object holder configured to hold an object; a fine positioning stage with a first actuator configured to cause the object holder to move with relatively shorter strokes; a coarse positioning stage with a second actuator configured to move with relatively longer strokes in comparison with the fine positioning stage; and a releasable coupling coupled to the fine positioning stage and the coarse positioning stage, the releasable coupling configured to switch between coupled and released configurations, the releasable couplingconfigured to mechanically couple the fine positioning stage to the coarse positioning stage in the coupled configuration during coarse positioning movements of the coarse positioning stage by the second actuator to transfer movement force from the coarse positioning stage to the fine positioning stage, and mechanically release the fine positioning stage from the coarse positioning stage in the released configuration during a processing operation such that the fine positioning stage is mechanically and dynamically decoupled from the coarse positioning stage, facilitating precision movements of the fine positioning stage.2. The system of clause 1, wherein the coupling is configured to provide a constraining force through physical mechanical contact with a pushing or pulling member of the coupling under compression or tension.3. The system of any of the previous clauses, wherein the semiconductor manufacturing apparatus comprises a lithography apparatus, and the processing operation comprises an exposure of a semiconductor wafer.4. The system of any of the previous clauses, wherein the coupling has a first side coupled to the fine positioning stage and a second side coupled to the coarse positioning stage, the coupling configured to transfer the movement force in a movement direction between the fine positioning stage and the coarse positioning stage.5. The system of any of the previous clauses, wherein the movement direction is a scanning direction of the motion control system.6. The system of any of the previous clauses, wherein the coupling comprises a variable stiffener configured to gradually increase in stiffness as a function of an amount of the movement force.7. The system of any of the previous clauses, wherein the variable stiffener comprises one or more variable stiffener actuators, and the stiffness is dependent on a preloading of the one or more variable stiffener actuators.8. The system of any of the previous clauses, wherein the coupling and the first actuator of the fine positioning stage are arranged in parallel in between the fine positioning stage and the coarse positioning stage.9. The system of any of the previous clauses, wherein the coupling is configured to provide a variable stiffness as a mechanical push-pull stiffness in a movement direction.10. The system of any of the previous clauses, wherein the coupling is configured to provide the variable stiffness as the mechanical push-pull stiffness in the movement direction only.11. The system of any of the previous clauses, wherein the variable stiffener comprises viscoelastic material.12. The system of any of the previous clauses, wherein the variable stiffener comprises a first portion on a first side of the object holder and / or the fine positioning stage, and a second portion on a second side of the object holder and / or the fine positioning stage.13. The system of any of the previous clauses, wherein the coupling comprises one or more active pushers configured to contact and push against the fine positioning stage during the coarse positioning movements of the coarse positioning stage.14. The system of any of the previous clauses, wherein the one or more active pushers are further configured to release the fine positioning stage during relatively shorter stroke movements of the fine positioning stage.15. The system of any of the previous clauses, wherein each active pusher comprises a pusher actuator coupled to a pushing member, the pusher actuator configured to cause the pushing member to push against and release the fine positioning stage.16. The system of any of the previous clauses, wherein the pusher actuator comprises a piezoelectric actuator.17. The system of any of the previous clauses, wherein the pusher actuator comprises a Lorentz actuator.18. The system of any of the previous clauses, wherein the pusher actuator comprises a magnetostrictive actuator.19. The system of any of the previous clauses, wherein the pushing member comprises a rod or a spring.20. The system of any of the previous clauses, wherein the one or more active pushers comprise two active pushers, with a first active pusher on a first side of the object holder and / or the fine positioning stage between the coarse positioning stage and the first side, and a second active pusher on a second side of the object holder and / or the fine positioning stage between the coarse positioning stage and the second side.21. The system of any of the previous clauses, wherein the coupling comprises one or more lines configured to: be taught during coarse positioning movements of the coarse positioning stage by the second actuator to transfer the movement force from the coarse positioning stage to the fine positioning stage, and slacken to mechanically release the fine positioning stage from the coarse positioning stage during fine positioning movements of the fine positioning stage by the first actuator such that the fine positioning stage is allowed to move with respect to the coarse positioning stage.22. The system of any of the previous clauses, wherein the one or more lines comprise one or more wires, ropes, fibers, flexures, sheets, or cables.23. The system of any of the previous clauses, wherein the one or more lines comprise at least a first line on a first side of the object holder and / or the fine positioning stage, and at least a second line on a second side of the object holder and / or the fine positioning stage.24. The system of any of the previous clauses, wherein the coupling further comprises one or more tensioners associated with each of the one or more lines, the one or more tensioners each configured to tension an associated line such that the line is taught during the coarse positioning movements.25. The system of any of claims 21-24, wherein the one or more lines are arranged along a movement direction of the coarse positioning stage.26. The system of any of the previous clauses, wherein a stiffness of the coupling in a movement direction during the coarse positioning movements is at least two orders of magnitude higher than a stiffness of the coupling in other directions and / or a stiffness of the coupling in any direction during the fine positioning movements.27. The system of any of the previous clauses, wherein the stiffness of the coupling in the other directions, and / or the stiffness of the coupling during the fine positioning movements is negligible.28. The system of any of the previous clauses, wherein the first actuator comprises one or more reluctance actuators and / or Lorentz actuators configured to move the fine positioning stage with relatively shorter stroke constant velocity movements; and wherein mechanically coupling the fine positioning stage to the coarse positioning stage during coarse positioning movements of the coarse positioning stage by the second actuator facilitates reducing a required mass, volume, and / or energy consumption of the one or more reluctance actuators because the one or more reluctance actuators need only control the relatively shorter stroke constant velocity movements.29. The system of any of the previous clauses, wherein the coarse positioning stage, the fine positioning stage, and the object holder together comprise a portion of a semiconductor lithography apparatus, an optical metrology inspection tool, or an e-beam inspection tool.30. The system of any of the previous clauses, wherein: the object holder comprises a reticle stage chuck or a wafer stage chuck of a semiconductor lithography apparatus, the object comprises a reticle or a semiconductor wafer, movement of the coarse positioning stage by the second actuator with relatively longer strokes in comparison with the fine positioning stage comprises acceleration or deceleration of the coarse positioning stage, and movement of the fine positioning stage by the first actuator with relatively shorter strokes in comparison with the coarse positioning stage comprises movement associated with a scan in the semiconductor lithography apparatus.31. A motion control method for a semiconductor manufacturing apparatus, comprising: holding an object with an object holder; coupling a fine positioning stage with a first actuator to the object holder, the fine positioning stage configured to cause the object holder to move with relatively shorter strokes; coupling a coarse positioning stage with a second actuator configured to move with relatively longer strokes in comparison with the fine positioning stage to the fine positioning stage; and switching a releasable coupling coupled to the fine positioning stage and the coarse positioning stage between coupled and released configurations, the releasable coupling configured to mechanically couple the fine positioning stage to the coarse positioning stage in the coupled configuration during coarse positioning movements of the coarse positioning stage by the second actuator to transfer movement force from the coarse positioning stage to the fine positioning stage, and mechanically release the fine positioning stage from the coarse positioning stage in the released configuration during a processing operation such that the fine positioning stage is mechanically and dynamically decoupled from the coarse positioning stage, facilitating precision movements of the fine positioning stage.32. The method of clause 31, wherein the coupling is configured to provide a constraining force through physical mechanical contact with a pushing or pulling member of the coupling under compression or tension.33. The method of any of the previous clauses, wherein the processing operation comprises an exposure of a semiconductor wafer.34. The method of any of the previous clauses, wherein the coupling has a first side coupled to the fine positioning stage and a second side coupled to the coarse positioning stage, the coupling configured to transfer the movement force in a movement direction between the fine positioning stage and the coarse positioning stage35. The method of any of the previous clauses, wherein the movement direction is a scanning direction of a motion control system.36. The method of any of the previous clauses, wherein the coupling comprises a variable stiffener configured to gradually increase in stiffness as a function of an amount of the movement force.37. The method of any of the previous clauses, wherein the variable stiffener comprises one or more variable stiffener actuators, and the stiffness is dependent on a preloading of the one or more variable stiffener actuators.38. The method of any of the previous clauses, wherein the coupling and the first actuator of the fine positioning stage are arranged in parallel in between the fine positioning stage and the coarse positioning stage.39. The method of any of the previous clauses, wherein the coupling is configured to provide a variable stiffness as a mechanical push-pull stiffness in a movement direction.40. The method of any of the previous clauses, wherein the coupling is configured to provide the variable stiffness as the mechanical push-pull stiffness in the movement direction only.41. The method of any of the previous clauses, wherein the variable stiffener comprises viscoelastic material.42. The method of any of the previous clauses, wherein the variable stiffener comprises a first portion on a first side of the object holder and / or the fine positioning stage, and a second portion on a second side of the object holder and / or the fine positioning stage.43. The method of any of the previous clauses, wherein the coupling comprises one or more active pushers configured to contact and push against the fine positioning stage during the coarse positioning movements of the coarse positioning stage.44. The method of any of the previous clauses, wherein the one or more active pushers are further configured to release the fine positioning stage during relatively shorter stroke movements of the fine positioning stage.45. The method of any of the previous clauses, wherein each active pusher comprises a pusher actuator coupled to a pushing member, the pusher actuator configured to cause the pushing member to push against and release the fine positioning stage.46. The method of any of the previous clauses, wherein the pusher actuator comprises a piezoelectric actuator.47. The method of any of the previous clauses, wherein the pusher actuator comprises a Lorentz actuator.48. The method of any of the previous clauses, wherein the pusher actuator comprises a magnetostrictive actuator.49. The method of any of the previous clauses, wherein the pushing member comprises a rod or a spring.50. The method of any of the previous clauses, wherein the one or more active pushers comprise two active pushers, with a first active pusher on a first side of the object holder and / or the fine positioning stage between the coarse positioning stage and the first side, and a second active pusher on a second side of the object holder and / or the fine positioning stage between the coarse positioning stage and the second side.51. The method of any of the previous clauses, wherein the coupling comprises one or more lines configured to: be taught during coarse positioning movements of the coarse positioning stage by the second actuator to transfer the movement force from the coarse positioning stage to the fine positioning stage, and slacken to mechanically release the fine positioning stage from the coarse positioning stage during fine positioning movements of the fine positioning stage by the first actuator such that the fine positioning stage is allowed to move with respect to the coarse positioning stage.52. The method of any of the previous clauses, wherein the one or more lines comprise one or more wires, ropes, fibers, flexures, sheets, or cables.53. The method of any of the previous clauses, wherein the one or more lines comprise at least a first line on a first side of the object holder and / or the fine positioning stage, and at least a second line on a second side of the object holder and / or the fine positioning stage.54. The method of any of the previous clauses, wherein the coupling further comprises one or more tensioners associated with each of the one or more lines, the one or more tensioners each configured to tension an associated line such that the line is taught during the coarse positioning movements.55. The method of any of the previous clauses, wherein the one or more lines are arranged along a movement direction of the coarse positioning stage.56. The method of any of the previous clauses, wherein a stiffness of the coupling in a movement direction during the coarse positioning movements is at least two orders of magnitude higher than a stiffness of the coupling in other directions and / or a stiffness of the coupling in any direction during the fine positioning movements.57. The method of any of the previous clauses, wherein the stiffness of the coupling in the other directions, and / or the stiffness of the coupling during the fine positioning movements is negligible.58. The method of any of the previous clauses, wherein the first actuator comprises one or more reluctance actuators and / or Lorentz actuators configured to move the fine positioning stage with relatively shorter stroke constant velocity movements; and wherein mechanically coupling the fine positioning stage to the coarse positioning stage during coarse positioning movements of the coarse positioning stage by the second actuator facilitates reducing a required mass, volume, and / or energy consumption of the one or more reluctance actuators because the one or more reluctance actuators need only control the relatively shorter stroke constant velocity movements.59. The method of any of the previous clauses, wherein the coarse positioning stage, the fine positioning stage, and the object holder together comprise a portion of a semiconductor lithography apparatus, an optical metrology inspection tool, or an e-beam inspection tool.60. The method of any of the previous clauses, wherein: the object holder comprises a reticle stage chuck or a wafer stage chuck of a semiconductor lithography apparatus, the object comprises a reticle or a semiconductor wafer, movement of the coarse positioning stage by the second actuator with relatively longer strokes in comparison with the fine positioning stage comprises acceleration or deceleration of the coarse positioning stage, and movement of the fine positioning stage by the first actuator with relatively shorter strokes in comparison with the coarse positioning stage comprises movement associated with a scan in the semiconductor lithography apparatus.

[0131] The concepts disclosed herein may be associated with any generic imaging and / or metrology system for imaging and / or analyzing 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) and / or 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, 248nm wavelength radiation, and / or other radiation. 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.

[0132] 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 lithography and / or metrology system, and its associated software may comprise separate embodiments, and / or these features may be used together in the same embodiment.

[0133] 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

CLAIMS:

1. A motion control system for a semiconductor manufacturing apparatus, comprising: an object holder configured to hold an object; a fine positioning stage with a first actuator configured to cause the object holder to move with relatively shorter strokes; a coarse positioning stage with a second actuator configured to move with relatively longer strokes in comparison with the fine positioning stage; and a releasable coupling coupled to the fine positioning stage and the coarse positioning stage, the releasable coupling configured to switch between coupled and released configurations, the releasable coupling configured to mechanically couple the fine positioning stage to the coarse positioning stage in the coupled configuration during coarse positioning movements of the coarse positioning stage by the second actuator to transfer movement force from the coarse positioning stage to the fine positioning stage, and mechanically release the fine positioning stage from the coarse positioning stage in the released configuration during a processing operation such that the fine positioning stage is mechanically and dynamically decoupled from the coarse positioning stage, facilitating precision movements of the fine positioning stage.

2. The system of claim 1, wherein the coupling is configured to provide a constraining force through physical mechanical contact with a pushing or pulling member of the coupling under compression or tension.

3. The system of claim 1 or 2, wherein the semiconductor manufacturing apparatus comprises a lithography apparatus, and the processing operation comprises an exposure of a semiconductor wafer.

4. The system of any of claims 1-3, wherein the coupling has a first side coupled to the fine positioning stage and a second side coupled to the coarse positioning stage, the coupling configured to transfer the movement force in a movement direction between the fine positioning stage and the coarse positioning stage.

5. The system of claim 4, wherein the movement direction is a scanning direction of the motion control system.

6. The system of any of claims 1-5, wherein the coupling comprises a variable stiffener configured to gradually increase in stiffness as a function of an amount of the movement force.

7. The system of claim 6, wherein the variable stiffener comprises one or more variable stiffener actuators, and the stiffness is dependent on a preloading of the one or more variable stiffener actuators.

8. The system of claim 6 or 7, wherein the coupling and the first actuator of the fine positioning stage are arranged in parallel in between the fine positioning stage and the coarse positioning stage.

9. The system of any of claims 6-8, wherein the coupling is configured to provide a variable stiffness as a mechanical push-pull stiffness in a movement direction.

10. The system of claim 9, wherein the coupling is configured to provide the variable stiffness as the mechanical push-pull stiffness in the movement direction only.

11. The system of any of claims 6-10, wherein the variable stiffener comprises viscoelastic material.

12. The system of any of claims 6-11, wherein the variable stiffener comprises a first portion on a first side of the object holder and / or the fine positioning stage, and a second portion on a second side of the object holder and / or the fine positioning stage.

13. The system of any of claims 1-5, wherein the coupling comprises one or more active pushers configured to contact and push against the fine positioning stage during the coarse positioning movements of the coarse positioning stage.

14. The system of claim 13, wherein the one or more active pushers are further configured to release the fine positioning stage during relatively shorter stroke movements of the fine positioning stage.

15. The system of claims 13 or 14, wherein each active pusher comprises a pusher actuator coupled to a pushing member, the pusher actuator configured to cause the pushing member to push against and release the fine positioning stage.

16. The system of claim 15, wherein the pusher actuator comprises a piezoelectric actuator.

17. The system of claim 15, wherein the pusher actuator comprises a Lorentz actuator.

18. The system of claim 15, wherein the pusher actuator comprises a magnetostrictive actuator.

19. The system of any of claims 15-18, wherein the pushing member comprises a rod or a spring.

20. The system of any of claims 13-19, wherein the one or more active pushers comprise two active pushers, with a first active pusher on a first side of the object holder and / or the fine positioning stage between the coarse positioning stage and the first side, and a second active pusher on a second side of the object holder and / or the fine positioning stage between the coarse positioning stage and the second side.

21. The system of any of claims 1-5, wherein the coupling comprises one or more lines configured to: be taught during coarse positioning movements of the coarse positioning stage by the second actuator to transfer the movement force from the coarse positioning stage to the fine positioning stage, and slacken to mechanically release the fine positioning stage from the coarse positioning stage during fine positioning movements of the fine positioning stage by the first actuator such that the fine positioning stage is allowed to move with respect to the coarse positioning stage.

22. The system of claim 21, wherein the one or more lines comprise one or more wires, ropes, fibers, flexures, sheets, or cables.

23. The system of claims 21 or 22, wherein the one or more lines comprise at least a first line on a first side of the object holder and / or the fine positioning stage, and at least a second line on a second side of the object holder and / or the fine positioning stage.

24. The system of any of claims 21-23, wherein the coupling further comprises one or more tensioners associated with each of the one or more lines, the one or more tensioners each configured to tension an associated line such that the line is taught during the coarse positioning movements.

25. The system of any of claims 21-24, wherein the one or more lines are arranged along a movement direction of the coarse positioning stage.

26. The system of any of claims 1-5, wherein a stiffness of the coupling in a movement direction during the coarse positioning movements is at least two orders of magnitude higher than a stiffness of the coupling in other directions and / or a stiffness of the coupling in any direction during the fine positioning movements.

27. The system of claim 26, wherein the stiffness of the coupling in the other directions, and / or the stiffness of the coupling during the fine positioning movements is negligible.

28. The system of any of claims 1-27, wherein the first actuator comprises one or more reluctance actuators and / or Lorentz actuators configured to move the fine positioning stage with relatively shorter stroke constant velocity movements; and wherein mechanically coupling the fine positioning stage to the coarse positioning stage during coarse positioning movements of the coarse positioning stage by the second actuator facilitates reducing a required mass, volume, and / or energy consumption of the one or more reluctance actuators because the one or more reluctance actuators need only control the relatively shorter stroke constant velocity movements.

29. The system of any of claims 1-28, wherein the coarse positioning stage, the fine positioning stage, and the object holder together comprise a portion of a semiconductor lithography apparatus, an optical metrology inspection tool, or an e-beam inspection tool.

30. The system of claim 29, wherein: the object holder comprises a reticle stage chuck or a wafer stage chuck of a semiconductor lithography apparatus, the object comprises a reticle or a semiconductor wafer, movement of the coarse positioning stage by the second actuator with relatively longer strokes in comparison with the fine positioning stage comprises acceleration or deceleration of the coarse positioning stage, and movement of the fine positioning stage by the first actuator with relatively shorter strokes in comparison with the coarse positioning stage comprises movement associated with a scan in the semiconductor lithography apparatus.