Patent Application
20170010544
The present invention relates to a coil assembly for an electromagnetic actuator, an electromagnetic actuator, a stage positioning device, a lithographic apparatus and a method for manufacturing a device.
A lithographic apparatus is a machine that applies a desired pattern onto a substrate, usually onto a target portion of the substrate. A lithographic apparatus can be used, for example, in the manufacture of integrated circuits (ICs). In such a case, a patterning device, which is alternatively referred to as a mask or a reticle, may be used to generate a circuit pattern to be formed on an individual layer of the IC. This pattern can be transferred onto a target portion (e.g.
including part of, one, or several dies) on a substrate (e.g. a silicon wafer). Transfer of the pattern is typically via imaging onto a layer of radiation-sensitive material (resist) provided on the substrate. In general, a single substrate will contain a network of adjacent target portions that are successively patterned. Conventional lithographic apparatus include so-called steppers, in which each target portion is irradiated by exposing an entire pattern onto the target portion at once, and so-called scanners, in which each target portion is irradiated by scanning the pattern through a radiation beam in a given direction (the “scanning”-direction) while synchronously scanning the substrate parallel or anti-parallel to this direction. In view of an ever increasing demand for integrated circuits, there is an ever increasing demand in an increased performance of lithographical apparatuses. In particular, there is an ever increasing desire to increase the throughput of such apparatuses. Such an increased throughput can e.g. be realized by increasing the number of substrates processed per unit of time or by increasing the size of the substrates, i.e. processing larger substrates would result in more ICs manufactured per unit of time.
Both options increase the burden put on the positioning devices applied during the scanning-exposure process. As such, it is desirable to improve the performance of positioning devices as applied in a lithographical apparatus. At present, the performance of such positioning devices, typically electromagnetic actuators or motors, is limited due to a less than optimal cooling of such devices.
It is desirable to provide in a positioning device having an improved cooling arrangement.
According to an aspect of the invention, there is provided a coil assembly for an electromagnetic actuator or motor, the coil assembly comprising:
According to another aspect of the invention, there is provided an electromagnetic actuator comprising a first member and a second member, wherein the first member comprising a coil assembly according to the invention and wherein the second member is configured to, in use, co-operate with the first member to generate a force between the first member and the second member upon energizing of the one or more coils.
According to yet another aspect of the present invention, there is provided a lithographic apparatus comprising:
According to yet another aspect of the invention, there is provided a device manufacturing method comprising transferring a pattern from a patterning device onto a substrate, comprising a step of positioning the patterning device relative to the substrate using an electromagnetic actuator or electromagnetic motor according to an embodiment of the present invention.
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, and in which:
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.
The support structure supports, i.e. bears the weight of, the patterning device. It holds the patterning device in a manner that depends on the orientation of the patterning device, the design of the lithographic apparatus, and other conditions, such as for example whether or not the patterning device is held in a vacuum environment. The support structure can 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 needed. The support structure may ensure that the patterning device is at a desired position, for example with respect to the projection system. Any use of the terms “reticle” or “mask” herein may be considered synonymous with the more general term “patterning device.”
The term “patterning device” used herein should be broadly interpreted as referring to any device that can be used to impart a radiation beam with a pattern in its cross-section so as 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 the target portion, such as an integrated circuit.
The patterning device may be transmissive or reflective. Examples of patterning devices include masks, programmable mirror arrays, and programmable LCD panels. Masks are well known in lithography, and include mask types such as binary, alternating phase-shift, and attenuated phase-shift, as well as various hybrid mask types. An example of a programmable minor array employs a matrix arrangement of small minors, each of which can be individually tilted so as to reflect an incoming radiation beam in different directions. The tilted minors impart a pattern in a radiation beam which is reflected by the minor matrix.
The term “projection system” used herein should be broadly interpreted as encompassing any type of projection system, including refractive, reflective, catadioptric, magnetic, electromagnetic and electrostatic optical systems, or any combination thereof, as appropriate for the exposure radiation being used, or for other factors such as the use of an immersion liquid or the use of a vacuum. Any use of the term “projection lens” herein may be considered as synonymous with the more general term “projection system”.
As here 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).
The lithographic apparatus may be of a type having two (dual stage) or more substrate tables or “substrate supports” (and/or two or more mask tables or “mask supports”). In such “multiple stage” machines the additional tables or supports may be used in parallel, or preparatory steps may be carried out on one or more tables or supports while one or more other tables or supports are being used for exposure.
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, so as to fill a space between the projection system and the substrate. An immersion liquid may also be applied to other spaces in the lithographic apparatus, for example, between the patterning device (e.g. mask) and the projection system. Immersion techniques can be used to increase 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 a liquid is located between the projection system and the substrate during exposure.
Referring to
The illuminator IL may include an adjuster AD configured to adjust the angular intensity distribution of the radiation beam. Generally, at least the outer and/or inner radial extent (commonly referred to as σ-outer and σ-inner, respectively) of the intensity distribution in a pupil plane of the illuminator can be adjusted. In addition, the illuminator IL may include various other components, such as an integrator IN and a condenser CO. The illuminator may be used to condition the radiation beam, to have a desired uniformity and intensity distribution in its cross-section.
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 (e.g. mask) MA, the radiation beam B passes through the projection system PS, which focuses the beam onto a target portion C of the substrate W. With the aid of the second positioning device PW and position sensor IF (e.g. an interferometric device, linear encoder or capacitive sensor), the substrate table WT can be moved accurately, e.g. so as to position different target portions C in the path of the radiation beam B. Similarly, the first positioning device PM and another position sensor (which is not explicitly depicted in
It is further worth nothing that an actuator or motor according to an embodiment of the present invention may also be applied for positioning of other components or elements in the lithographic apparatus, e.g. optical elements, masking blades, etc. In the case of a stepper (as opposed to a scanner) the support structure (e.g. mask table) MT may be connected to a short-stroke actuator only, or may be fixed. Patterning device (e.g. mask) MA and substrate W may be aligned using patterning device alignment marks M1, M2 and substrate alignment marks P1, 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 (e.g. mask) MA, the patterning device alignment marks may be located between the dies.
The depicted apparatus could be used in at least one of the following modes:
Combinations and/or variations on the above described modes of use or entirely different modes of use may also be employed.
In accordance with an embodiment of the present invention, the term ‘magnetic yoke’ is used to denote a structure made from a material having a high relative permeability (e.g. >100) such as ferromagnetic materials such as steel or rare-earth alloys such as CoFe, SiFe or the like. Typically, a magnetic yoke is a laminated core made by assembling a plurality of ferromagnetic sheets, in order to reduce so-called iron core losses.
The coil arrangement as shown further comprises a cooling member 140 which is mounted to an outer surface of the magnetic yoke 110 and e.g. provided with cooling channels 150 through which a cooling fluid can flow.
In the known arrangement, the cooling of the coils 130 has been found to be far from optimal, resulting in either a poor performance of the motor (in case the current through the coils is kept comparatively low) or a comparatively high operating temperature of the coils, thus posing a risk to a degradation of isolation of the coils.
In accordance with an embodiment of the present invention, an alternative way of cooling a coil assembly of an electromagnetic motor is proposed.
In the embodiment as shown, the magnetic yoke 210 has two slots, indicated by the dotted line 220. A coil 230 is mounted in said pair of slots 220. Compared to the arrangement of
In the arrangement as shown, both coil sides that are mounted in the pair of slots 220 are provided with a cooling member 240.
Within the meaning of the present invention, the surfaces 260 of the coil 230, i.e. the surfaces facing a side surface of the slots 220, are referred to as side surfaces of the coil, whereas the surface 262 of the coil facing the bottom of the slot is referred to as the bottom surface of the coil and the surface 264 of the coil near the top of the slot is referred to as the top surface of the coil.
The cooling member as applied in an embodiment of the present invention, i.e. mounted to a surface of a coil which is at least partly mounted in a magnetic yoke, provides in a more effective and direct cooling of the coil. Compared to the known arrangement as shown in
In accordance with an embodiment of the present invention, various options exist for the application of the cooling member 240 as shown.
In the embodiment as shown in
In the embodiment as shown, the magnetic yoke 310 has two slots, indicated by the dotted line 320. A coil 330 is mounted in said pair of slots 320. Compared to the arrangement of
In an embodiment of the present invention, a coil assembly is provided which comprises both the cooling member 240 as shown in
The positioning of the cooling member as shown in
In an embodiment, the coil assembly according to the present invention comprises multiple coil sides per slot, i.e. each slot accommodating coil sides of different coils. In such an arrangement, a cooling member can be positioned in between the coil sides of the different coils.
Note that the same principle can be applied when more than two coil sides are occupying one slot as well. As such, the cooling member as shown in
In general, the coil assembly according to the present invention can be applied in electromagnetic actuators, such as actuators used in the aforementioned short stroke module of the positioning device PM or PW, and in electromagnetic motors such as linear or planar motors as can be used in long stroke modules of the positioning device PM or PW.
In general, an electromagnetic actuator or motor comprises a coil assembly as a first member, cooperating with a second member, thereby generating a force between the first member and the second member.
In so-called reluctance type motors or actuators, the second member comprises a magnetic member such as a magnetic yoke, e.g. made from a ferromagnetic material having a relative permeability μr>100. In such reluctance type actuators or motors, an attractive force is generated between the first member and the second member when a current is provided to the coil or coils of the coil assembly.
In so-called permanent magnet motors or actuators, the second member comprises one or more permanent magnets, optionally mounted to a magnetic member such as a magnetic yoke.
The followings
Such an actuator may e.g. be applied for accurate, short stroke, positioning of an object table such as a substrate table or a pattering device support. In such arrangement, a plurality of such actuators may e.g. be applied to position the object table in multiple degrees of freedom, e.g. 6 DOF (degrees of freedom). In such arrangement, the second members of the actuators (e.g. second member 760 of
As an alternative to the application of the thermal insulation layer 910, a cooling member, similar to the cooling members 840, may also be applied to the coil surfaces facing the side surfaces 920 of the slots.
It is worth noting that the application of the thermal insulation layer 910, the application of an additional cooling member 900 in the magnetic yoke 810 or the application of a cooling member to a coil surface facing a side surface of the slots may be applied in all of the above described embodiments of the coil assembly according to the invention.
The electromagnetic motor as schematically shown in
The cooling member as applied in the coil assembly according to the present invention, i.e. cooling members 240, 340, 540, 640, 740 or 840 as described above, can be implemented in various ways.
As an example, the cooling member can comprise one or more cooling channels that are provided in an enclosure, e.g. a stainless steel or ceramic enclosure. As mentioned above, in case the cooling member is facing a permanent magnet and is configured to displace relative to the permanent magnet, care should be taken to avoid excessive damping or losses. The one or more cooling channels may e.g. be configured to receive a cooling fluid such as a gas or a liquid.
As an alternative, the cooling member could also comprise a heat pipe or the like to remove the heat generated in the coil or coils.
Although specific reference may be made in this text to the use of lithographic apparatus in the manufacture of ICs, it should be understood that the lithographic apparatus described herein may have other applications, such as the manufacture of integrated optical systems, guidance and detection patterns for magnetic domain memories, flat-panel displays, liquid-crystal displays (LCDs), thin-film magnetic heads, etc. The skilled artisan will appreciate that, in the context of such alternative applications, any use of the terms “wafer” or “die” herein may be considered as synonymous with the more general terms “substrate” or “target portion”, respectively. The substrate referred to herein may be processed, before or after exposure, in for example a track (a tool that typically applies a layer of resist to a substrate and develops the exposed resist), a metrology tool and/or an inspection tool. Where applicable, the disclosure herein may be applied to such and other substrate processing tools. Further, the substrate may be processed more than once, for example in order to create a multi-layer IC, so that the term substrate used herein may also refer to a substrate that already contains multiple processed layers.
Although specific reference may have been made above to the use of embodiments of the invention in the context of optical lithography, it will be appreciated that the invention may be used in other applications, for example imprint lithography, and where the context allows, is not limited to optical lithography. In imprint lithography a topography in a patterning device MA defines the pattern created on a substrate W. The topography of the patterning device MA may be pressed into a layer of resist supplied to the substrate whereupon the resist is cured by applying electromagnetic radiation, heat, pressure or a combination thereof. The patterning device MA is moved out of the resist leaving a pattern in it after the resist is cured.
The terms “radiation” and “beam” used herein encompass all types of electromagnetic radiation, including ultraviolet (UV) radiation (e.g. having a wavelength of or about 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.
The term “lens”, where the context allows, may refer to any one or combination of various types of optical components, including refractive, reflective, magnetic, electromagnetic and electrostatic optical components.
The descriptions above are intended to be illustrative, not limiting. Thus, it will be apparent to one skilled in the art that modifications may be made to the invention as described without departing from the scope of the claims set out below.
This application claims the benefit of U.S. provisional application 61/930,343, which was filed on Jan. 22, 2014 and which is incorporated herein in its entirety by reference.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2014/078677 | 12/19/2014 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 61930343 | Jan 2014 | US |
