CN111095113B

CN111095113B - Abrasive tool and method for removing contaminants from an object holder

Info

Publication number: CN111095113B
Application number: CN201880059335.7A
Authority: CN
Inventors: D·索拉比巴巴黑德利; K·M·利维; 王青松
Original assignee: ASML Holding NV
Current assignee: ASML Holding NV
Priority date: 2017-09-15
Filing date: 2018-08-14
Publication date: 2023-12-29
Anticipated expiration: 2038-08-14
Also published as: WO2019052757A1; KR20200052299A; NL2021464A; CN111095113A

Abstract

A method of treating a support surface of an object holder using an abrasive tool comprising a substantially planar surface for positioning on and contacting the object holder, wherein the substantially planar surface of the abrasive tool has a roughness selected from the range of about 1nm Ra to about 100nm Ra, a flatness of less than or equal to about 3000nm, or a roughness of at least about 15nm Ra, and a flatness of less than or equal to about 3000nm in a predetermined area of the substantially planar surface.

Description

Abrasive tool and method for removing contaminants from an object holder

Cross Reference to Related Applications

The present application claims priority from U.S. provisional patent application No. 62/559,468 filed on day 15, 9, 2017, which is incorporated herein by reference in its entirety.

Technical Field

The present description relates to object holders and techniques for cleaning and/or abrading the surfaces of object holders.

Background

Lithographic apparatus can be used, for example, in the manufacture of Integrated Circuits (ICs) or other devices. In this case, the patterning device (e.g., mask) may contain or provide a pattern corresponding to an individual layer of the device (the "design layout"), and this pattern may be transferred onto a target portion (e.g., comprising one or more dies) of a substrate (e.g., a silicon wafer) that has been coated with a layer of radiation-sensitive material (the "resist"), by a method such as irradiating the target portion through the pattern on the patterning device. Typically, a single substrate contains a plurality of adjacent target portions to which a pattern is successively transferred by a lithographic apparatus, one target portion at a time. In one type of lithographic apparatus, the pattern on the entire patterning device is transferred onto a target portion at a time; such devices are commonly referred to as steppers. In an alternative device, commonly referred to as a step-and-scan device, the projection beam scans the patterning device in a given reference direction (the "scanning" direction) while simultaneously moving the substrate parallel or anti-parallel to the reference direction. Different portions of the pattern on the patterning device are progressively transferred to a target portion. Since typically the lithographic apparatus will have a magnification factor M (typically < 1), the speed F of the substrate movement will be a factor M times the speed of the projection beam scanning patterning device.

Prior to the device fabrication process of transferring the pattern from the patterning device to the substrate of the device manufacturing process, the substrate may undergo various device fabrication processes of the device manufacturing process, such as priming, resist coating, and soft baking. After exposure, the substrate may be subjected to other device fabrication processes of the device fabrication process (e.g., post Exposure Bake (PEB), develop, and hard bake). This array of device fabrication processes is used as a basis for fabricating individual layers of devices (e.g., ICs). The substrate may then undergo various device fabrication processes of the device fabrication process, such as etching, ion implantation (doping), metallization, oxidation, chemical mechanical polishing, etc., all of which are intended to complete the individual layers of the device. If several layers are required in the device, the entire process or variations thereof are repeated for each layer. Eventually, the device will appear in each target portion on the substrate. If there are multiple devices, the devices may be separated from each other by techniques such as dicing or sawing, and then individual devices may be mounted on a carrier and connected to pins or the like.

Thus, fabricating a device (e.g., a semiconductor device) typically involves processing a substrate (e.g., a semiconductor wafer) using several fabrication processes to form various features and layers of the device. Such layers and features are typically fabricated and processed using, for example, deposition, photolithography, etching, chemical mechanical polishing, and ion implantation. The plurality of devices may be fabricated on a plurality of dies on a substrate and then separated into individual devices. The device manufacturing process may be considered a patterning process. The patterning process includes a patterning step (e.g., optical or nanoimprint lithography using a lithographic apparatus) to provide a pattern on the substrate, and typically, but optionally, involves one or more associated pattern processing steps (e.g., developing the resist by a developing apparatus, baking the substrate using a baking tool, etching using a pattern using an etching apparatus, etc.). In addition, one or more metrology processes are typically involved in the patterning process.

Disclosure of Invention

For example, due to imaging and overlay requirements as part of the patterning process, the accuracy of the surfaces of the object holder and table (or object holder in general) is often measured. Such object holders may include a substrate support that holds a substrate onto which the pattern is projected, and may also include other object holders (e.g., patterning device supports).

The object holder may become contaminated. For example, the object holder may have one or more protrusions on which the object is supported. Because the object holder has only a limited contact area with the support surface of the object holder, these protrusions generally have the purpose of: reducing the likelihood of contamination between the actual support surface of the object holder and the object. These one or more protrusions may also be referred to as one or more nubs or nubs.

However, even the top surface of the protrusions may be subject to contamination. Such contaminants have been found to be incompletely removable by standard cleaning methods (e.g., wiping, stamping (stamp), etc.). Additionally or alternatively, such standard cleaning methods may provide further problems (e.g., particles (e.g., fibers) or chemical residues) on the surface, damage or further contamination of the surface, environmental problems, and/or require secondary cleaning to remove particles and/or residues from previous cleaning (which may not be completely clean in some cases). Additionally, tough contaminants may not be removed using standard cleaning methods. Contaminants of a few nanometers can change flatness and severely impact specifications and performance.

Load grid error (sometimes referred to as Wafer Load Grid (WLG) error) is another potential defect in the object holder caused by contamination. Loading grid errors are offsets in a direction generally parallel to the support plane/surface of the object holder. In the case where the object is supported by one or more protrusions, loading grid errors may be caused by relatively high friction between the object (e.g., a radiation-sensitive substrate) and the top(s) of the one or more protrusions of the object holder. Contamination may be a cause of problems associated with loading grid errors, but loading grid errors may also be caused by other causes (e.g., too smooth surfaces). Thus, both contamination itself and loading grid errors (which may be due at least in part to contaminants) can potentially cause errors (e.g., overlay errors) from the lithographic process.

Thus, it would be advantageous to provide improved methods and tools for removing contaminants from an object holder, particularly an object holder having one or more protrusions, for example, such that errors (e.g., loading grid errors, overlay errors, etc.) may be reduced or substantially avoided. It would be advantageous, for example, to provide improved methods and tools to provide roughness to an object holder, particularly an object holder having one or more protrusions (e.g., to reduce the coefficient of friction of a support surface and thus help reduce loading grid errors), such that errors (e.g., loading grid errors, overlay errors, etc.) may be reduced or substantially avoided. Thus, in one embodiment, an apparatus is provided for removing contaminants and/or providing roughness to a surface of an object holder, in particular a sensitive or nano-flat surface.

In one embodiment, a method of treating a support surface of a holder configured to hold an object is provided, the object holder comprising a plurality of protrusions extending from a body of the holder and configured to provide a support surface for the object, the method comprising: providing an abrasive tool comprising a substantially planar surface for positioning on and contacting an object holder; positioning a substantially planar surface of the abrasive tool in contact with a support surface of the object holder; and providing relative movement between the abrasive tool and at least a portion of the object holder to remove contaminants from the protrusions when the abrasive tool is in contact with the support surface, wherein the substantially planar surface of the abrasive tool has a roughness selected from the range of about 15nm Ra to about 50nm Ra, has a flatness of less than or equal to about 500nm, or the substantially planar surface of the abrasive tool has a roughness of at least about 15nm Ra and a flatness of less than or equal to about 500nm in a predetermined area of the substantially planar surface.

In one embodiment, an abrasive tool is provided that is configured to be positioned on and in contact with an object holder, the object holder comprising a plurality of protrusions that provide a support surface for an object, the abrasive tool comprising a substantially planar surface arranged to abrade the support surface by relative movement between the substantially planar surface and the support surface to remove contaminants from the support surface, wherein the substantially planar surface of the abrasive tool has a roughness selected from a range of about 15nm Ra to about 50nm Ra, has a flatness of less than or equal to about 500nm, or the substantially planar surface of the abrasive tool has a roughness of at least about 15nm Ra and a flatness of less than or equal to about 500nm in a predetermined area of the substantially planar surface.

In one embodiment, an abrasive tool is provided that is configured to be positioned on and in contact with an object holder, the object holder comprising a plurality of protrusions that provide a support surface for an object, the abrasive tool comprising a substantially planar surface arranged to abrade the support surface by relative movement between the substantially planar surface and the support surface to roughen the support surface, wherein the substantially planar surface of the abrasive tool has a roughness selected from about 200nm Ra to about 500nm Ra.

In one embodiment, there is provided a lithographic apparatus comprising: a patterning device support configured to support a patterning device; a patterning device configured to pattern the beam of radiation to form a patterned beam of radiation; a projection system configured to project the patterned radiation beam onto a target portion of the substrate; a substrate holder configured to hold a substrate; a system arranged to remove contaminants from a support surface of an object holder, the object holder comprising a plurality of protrusions providing a support surface for the object, the system comprising an abrasive tool comprising a substantially planar surface for positioning on and contacting the object holder, wherein the substantially planar surface of the abrasive tool has a roughness selected from a range of about 15nm Ra to about 50nm Ra, a roughness selected from a range of about 200nm Ra to about 500nm Ra, or a flatness of less than or equal to about 500nm, or a roughness of at least about 15nm Ra and a flatness of less than or equal to about 500nm in a predetermined area of the substantially planar surface.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this 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, and in which:

FIG. 1 schematically depicts a lithographic apparatus according to an embodiment of the disclosure;

FIG. 2 schematically depicts an embodiment of a lithographic cell or cluster according to one embodiment of the present disclosure;

FIG. 3 schematically depicts a cross-sectional view of an object holder according to one embodiment of the present disclosure;

FIG. 4 is a schematic detailed top view of a protrusion on the object holder of FIG. 2 with contaminants thereon;

FIG. 5 is a detailed close-up view of protrusions on an object holder after grinding/cleaning according to one embodiment of the present disclosure;

FIG. 6 illustrates a schematic example of an abrasive tool for abrading an object holder according to one embodiment of the present disclosure;

FIG. 7 schematically depicts movement of an abrasive tool across an object holder according to a method of abrading an object holder as disclosed in one embodiment of the present disclosure;

FIG. 8 is a detailed close-up view of a protrusion on an object holder, the protrusion having contaminants thereon;

FIG. 9 is a detailed close-up view of the protrusions of FIG. 8 after grinding/cleaning, according to one embodiment of the present disclosure; and

FIG. 10 is a block diagram of an example computer system, according to an example embodiment of the present disclosure.

The figures are not necessarily drawn to scale. Any values, dimensions shown in the figures and drawings are for illustrative purposes only and may or may not represent actual or preferred values or dimensions. Where applicable, some or all of the features may not be shown to aid in the description of the underlying features. In the drawings.

Detailed Description

FIG. 1 schematically depicts a lithographic apparatus according to an embodiment of the invention. The apparatus includes:

an illumination system (illuminator) IL configured to condition a radiation beam B (e.g. UV radiation or DUV radiation);

a support structure (e.g. a mask table) MT constructed to hold 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;

a substrate table (e.g., a wafer table) WT configured to hold a substrate (e.g., a resist-coated wafer) W and connected 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) of the substrate W.

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 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 (e.g., such as for example whether or not the patterning device is held in a vacuum environment). The support structure may use mechanical, vacuum, electrostatic or other clamping techniques to hold the patterning device. The support structure may be, for example, a frame or a table, 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. Any use of the term "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 such 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. Typically, the pattern imparted to the radiation beam will correspond to a particular functional layer in a device being created in the target portion (e.g., 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. One example of a programmable mirror array employs a matrix arrangement of small mirrors, each of which can be individually tilted so as to reflect an incoming radiation beam in different directions. The tilted mirrors impart a pattern in a radiation beam which is reflected by the mirror 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 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 depicted herein, the apparatus is transmissive (e.g., employing a transmissive mask). Alternatively, the apparatus may be reflective (e.g. employing a programmable mirror array of a type as described above, or employing a reflective mask).

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

Referring to FIG. 1, the illuminator IL receives a radiation beam from a radiation source SO. For example, when the source is an excimer laser, the source and the lithographic apparatus may be separate entities. 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 lithographic 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.

The illuminator IL may comprise an adjuster AD for adjusting the angular intensity distribution of the radiation beam. In general, the intensity distribution of at least the outer and/or inner radial extent (commonly referred to as σ -outer and σ -inner, respectively) in a pupil plane of the illuminator can be adjusted. Additionally, the illuminator IL may comprise various other components, such as an integrator IN and a beamformer 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. After passing through patterning device MA, radiation beam B passes through projection system PL, which focuses the beam onto a target portion C of substrate W. By means of the second positioner 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 positioner PM and another position sensor (which is not explicitly depicted in fig. 1) can be used to accurately position the patterning device MA with respect to the path of the radiation beam B, e.g. after mechanical retrieval from a mask library, or during a scan. In general, movement of the support structure MT may be realized with the aid of a long-stroke module (coarse positioning) and a short-stroke module (fine positioning), which form part of the first positioner PM. Similarly, movement of the substrate table WT may be realized with the aid of a long-stroke module and a short-stroke module, which form part of the second positioner PW. In the case of a stepper (as opposed to a scanner) the 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 M1, M2 and substrate alignment marks P1, P2. Although the substrate alignment marks are shown as occupying dedicated target portions, they may be located in spaces between target portions (these are referred to as scribe-lane alignment marks). Similarly, in situations where more than one die is provided on the patterning device MA, the patterning device alignment marks may be located between the dies.

The depicted device 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 an entire 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 different target portions 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-) magnification and image reversal characteristics of the projection system PS. In scan mode, the maximum size of the exposure field limits the width (in the non-scanning direction) of the target portion in a single dynamic exposure, while the length of the scanning motion determines the height (in the scanning direction) of the target portion.

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, a pulsed radiation source is typically 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.

As shown in fig. 2, the lithographic apparatus LA may form part of a lithographic cell LC, sometimes also referred to as a lithographic cell (lithocell) or a lithographic cluster, which also includes an apparatus to perform one or more pre-exposure and post-exposure processes on a substrate. Conventionally, these apparatuses include one or more spin coaters SC for depositing a resist layer, one or more developers DE for developing the exposed resist, one or more chill plates CH, and one or more bake plates BK. The substrate transport apparatus or robot RO picks up a substrate from the input/output ports I/O1, I/O2, moves the substrate between different processing apparatuses, and transfers it to the feed station LB of the lithographic apparatus. These devices, commonly referred to as tracks, are under the control of a track control unit TCU, which itself is controlled by a supervisory control system SCS, which also controls the lithographic apparatus via a lithographic control unit LACU. Thus, different equipment may be operated to maximize throughput (e.g., substrates processed per unit time) and processing efficiency. The lithography unit LC may further include: one or more etchers for etching the substrate; one or more measurement devices configured to measure a parameter of the substrate; and/or one or more Chemical Mechanical Planarization (CMP) tools to smooth the surface of the substrate. The measurement device may include an optical measurement device (e.g., a scatterometer, a scanning electron microscope, etc.) configured to measure a physical parameter of the substrate. The measurement device may be incorporated in the lithographic apparatus LA. One embodiment of the present disclosure may be implemented in or with the management control system SCS or the lithography control unit LACU. For example, data from the supervisory control system SCS or lithography control unit LACU may be used by embodiments of the disclosure, and one or more signals from embodiments of the disclosure may be provided to the supervisory control system SCS or lithography control unit LACU.

As described above, the object holder may become contaminated. Accordingly, in one embodiment, a cleaning technique for cleaning at least a portion of an object holder is described herein. Furthermore, as discussed further herein, it may be desirable to provide roughness to the surface of the object holder. Thus, according to one embodiment, a roughening technique for roughening at least a portion of an object holder is described herein.

The embodiments herein focus on a substrate table WT as an object holder, and a substrate W as an object. However, the description herein may be applied to other object holders (e.g., patterning device support structure MT). Furthermore, the description herein may be applied to object holders in apparatuses other than lithographic apparatuses. For example, the description herein may be applied to object holders in track tools, etch tools, chemical Mechanical Planarization (CMP) tools, and the like. Furthermore, the description herein may be more generally applied to structures used in patterning processes that are susceptible to contamination and/or are desirably roughened.

Fig. 2 is a schematic view of a substrate holder. In this example, a substrate table WT is depicted, the substrate table WT supporting a substrate chuck 22, the substrate chuck 22 supporting a substrate. However, such a substrate chuck is not necessary. As shown in the cross-sectional view of FIG. 2, the substrate chuck 22 may be part of a movable substrate table WT and directly support a substrate W. Thus, in one embodiment, the substrate chuck 22 may be an object holder. In this embodiment, the substrate chuck 22 is in or on the substrate table base 24. In one embodiment, the substrate chuck 22 and the substrate table base 24 are removable. In one embodiment, the substrate table WT forms a recess in which the substrate W is located. The recess may be formed by the substrate table base 24, may be formed by another structure (not shown in fig. 2) located on the substrate table base 24, or a combination thereof.

As shown, the chuck 22 is configured to provide one or more support surfaces to directly contact and support the substrate W. In one embodiment, the substrate chuck 22 has one or more protrusions 20 (e.g., nubs or protrusions), which one or more protrusions 20 protrude or extend substantially perpendicularly from the surface of the chuck 22. Thus, in this case, the substrate table WT may be referred to as a convex spot table or a burl table. In particular, during operation, the lower surface or backside of the substrate W may be supported on the upper surface(s) of the one or more protrusions 20. Thus, the top portion(s) of the one or more protrusions define an effective support plane for the substrate.

Thus, the substrate table WT is configured such that when the substrate W is positioned on the substrate chuck 22, i.e. on at least one of the one or more protrusions 20, the upper surface of the substrate W lies in a predetermined plane in relation to the propagation direction of the exposure radiation. In one embodiment, the surface of the substrate W is oriented transverse to the direction of propagation of the beam.

The arrangement of the one or more protrusions 20 is not limiting. In one embodiment, the protrusions are arranged in an array, such as shown in a detailed top view of at least a portion of the table surface in fig. 3-5 and 7. Moreover, the surface area of the substrate chuck 22 and/or the projection(s) thereof in contact with the substrate W are not intended to be limiting.

In one embodiment, the substrate W may be held on the substrate chuck 22 using, for example, a vacuum system or an electrostatic clamping arrangement (not shown). Thus, in the case of a vacuum system, the space around the burls below the substrate may be subjected to a low pressure in order to draw the substrate W onto the substrate chuck 22. Thus, the substrate W may be vacuum clamped to the substrate chuck 22.

In one embodiment, where the substrate chuck 22 is removable, the substrate chuck 22 may be held on the substrate base 24 using, for example, a vacuum system or an electrostatic clamping arrangement (not shown). Thus, in the case of a vacuum system, the substrate chuck 22 may be vacuum clamped to the substrate base 24.

The above-described arrangement of one or more protrusions 20 may minimize or reduce the total area of the substrate W in contact with the substrate table WT and thus generally reduce the total amount of contaminants between the substrate W and the corresponding surface of the substrate table WT in contact with the substrate W. However, as previously described, when contaminants are present on one or more protrusions, they may have undesirable consequences, such as deformation of the substrate W in a direction substantially perpendicular to the radiation receiving surface of the substrate and/or loading grid errors.

In some cases, contaminants will remain even after standard and known wiping and imprinting processes are used on the substrate table WT. For example, fig. 4 and 5 illustrate examples of refractory contaminants or debris at the micron-sized level that remain on the protrusions 20 of the substrate table WT and cannot be cleaned by this conventional cleaning method. The arrows provided on fig. 3 emphasize the location of the contaminants on the protrusions. Such contaminants may have a thickness or level of nanometers (nm) on the protrusions, but can cause significant errors when the substrate W is placed thereon and exposed to radiation.

Accordingly, the present disclosure describes a method and tool configured for nano-scale surface cleaning and removal of contaminants/debris from at least protrusions of a substrate table WT such that the surface of the substrate table may be protected without substantially affecting its performance.

In an embodiment, at least one abrasive tool having a substantially planar surface is provided for positioning on and in contact with an object holder such as a substrate table WT. In one embodiment, the abrasive tool removes contaminants from the object holder, such as at least the protrusions (e.g., protrusions 20) of the object holder. In one embodiment, the abrasive tool provides roughness to the surface of the object holder (e.g., to reduce the coefficient of friction of the support surface and thus help reduce loading grid errors), such as at least to the protrusions of the object holder (e.g., protrusions 20).

Fig. 6 illustrates an example of an abrasive tool 30, for example in the form of a disk. However, the shape and form of the abrasive tool is not limited to the illustrated embodiment; for example, it may be rectangular (or other shape) rather than necessarily plate-like as depicted in the figures. The tool 30 has at least one substantially planar abrasive surface 32. The substantially planar abrasive surface 32 is configured to be positioned against, and/or to be in contact with, a support surface of the object holder during use. In one embodiment, surface 32 is configured to contact at least an upper surface of the object holder. In one embodiment, the surface 32 is configured to contact an upper surface of at least the protrusion of the object holder.

The tool 30 is configured to move across the object holder while in contact with the support surface of the object holder. In this context, movement "across" and "in contact with" a support surface refers to relative movement between the tool 30 and the support surface while the tool is in contact with the support surface; thus, the tool 30 may be moved, the support surface may be moved, or both. In one embodiment, the support surface is at least an upper surface or top portion of a protrusion of the object holder. In one embodiment, the tool moves across a support surface provided by a plurality of protrusions of the object holder. Moving the tool across and in contact with the support surface causes the tool 30 to be used to abrade against the support surface in order to remove contaminants from the support surface (e.g., from the support surface provided by the protrusions of the object holder, such as the protrusions 20).

The body of the abrasive tool 30 and the substantially planar surface 32 may be integrally formed or separate from one another. In one embodiment, the body and surface 32 of the tool 30 are both formed from a single material. For example, in one embodiment, the abrasive tool 30 is formed from a homogeneous, non-natural (artificial or man-made) material. In one embodiment, the material is sintered.

As noted previously, the shape and/or form of the body of the abrasive tool 30 (including its substantially planar surface) is not intended to be limiting. The shape of the tool 30 and/or the substantially planar surface 32 may be, for example, circular, elliptical, polygonal, triangular, or teardrop-shaped. For example, the shape of the body of tool 30 may be based on a design that is appropriate for the palm of a person's hand (in the case of manual use). In one embodiment, the body of the abrasive tool 30 has a different shape than the substantially planar surface 32. For illustration and illustration purposes only, tool 30 and surface 32 are shown in fig. 5 as a unitary form and have a disk shape.

The transverse dimension D (e.g., diameter or width) of the tool 30 and/or the surface 32 may be up to, for example, about 50mm. In one embodiment, the lateral dimension of the surface 32 is selected from the range of about 20mm to about 300mm, from the range of about 20mm to about 100mm, or from the range of about 20mm to about 50mm. In one embodiment, surface 32 has a lateral dimension of at least 50mm.

The thickness of the surface 32 and/or the abrasive tool 30 may vary. In one embodiment, the thickness T of the surface 32 and/or the abrasive tool 30 is selected from the range of about 5mm to about 100 mm. In one embodiment, the total thickness T of the abrasive tool 30 having the surface 32 is selected from a range of about 10mm to about 50mm, from a range of about 10mm to about 25mm, or about 15mm.

In one embodiment, the roughness of the surface 32 of the abrasive tool 30 may be selected from a range of about 1nm Ra to about 2000nm Ra, or from a range of about 1nm Ra to about 1200nm Ra. In one embodiment, the surface 32 of the abrasive tool 30 may have a roughness of at least about 15nm Ra. In one embodiment, the roughness of the surface 32 is selected from a range of about 1nm Ra to about 100nm Ra, or from a range of about 15nm Ra to about 50nm Ra.

In one embodiment, surface 32 has a desired high degree of flatness. The surface 32 has two general areas: a first predetermined area (e.g., an area of the surface 32 designed to conform to the protrusion of the object holder) designed for consistent contact with the surface of the object holder; and a second predetermined region that is a transition of the first defined region to another surface (e.g., edge 36 of surface 32 may have a chamfer or curve), and that may have relatively infrequent contact with the surface of the object holder. In one embodiment, the chamfer or curve of the center portion of the surface 32 minus the edge 36 may be a first predetermined area for having a particular flatness. In one embodiment, the flatness of the first predetermined area of the surface 32 is less than about 600nm in that area. In one embodiment, the flatness of the first predetermined area of the surface 32 is less than about 300nm in that area. In one embodiment, the flatness of the first predetermined area of the surface 32 is less than about 100nm in that area. In one embodiment, the flatness may be greater than about 100nm within the first predetermined area.

In one embodiment, the flatness of the first predetermined area of the surface 32 is selected in the area from a range of about 20nm to about 3000nm for cleaning and/or roughening. In one embodiment, the flatness is lower for lower roughness and higher for higher roughness. Thus, in one embodiment, for roughness (e.g., for cleaning) taken from a range of about 1nm Ra to 100nm Ra, the flatness may be selected from a range of about 20nm to about 400 nm. In one embodiment, for roughness taken from the range of about 100nm Ra to 2000nm Ra (e.g., for roughening), the flatness may be selected from the range of about 400nm to about 3000 nm.

In one embodiment, the flatness of the surface 32 in the first predetermined area is about 150nm/cm or less, about 100nm/cm or less, about 75nm/cm, about 50nm/cm or less, or about 25nm/cm or less per unit lateral dimension of the surface. Thus, for example, for a lateral dimension area of 5cm, and a flatness of about 150nm/cm per unit lateral dimension of the surface, the area has a flatness of 750nm or less.

In one embodiment, the hardness of the surface 32 is greater than about 10GPa. In one embodiment, the hardness of the surface 32 is selected from the range of about 10GPa to about 30 GPa.

In one embodiment, at least the surface 32 of the tool 30 is made of stone (stone), granite, or a ceramic material. In one embodiment, surface 32 comprises or consists essentially of a material selected from the group consisting of: alumina (Al) ₂ O ₃ ) Silicon carbide (SiC), silicon nitride (Si) ₃ N ₄ ) Aluminum nitride (AlN) and/or chromium nitride (CrN).

FIG. 7 schematically depicts a method of relative movement between an abrasive tool 30 and an object holder such as a substrate table WT. In one embodiment, the abrasive tool 30 is moved across the surface by sliding the abrasive tool 30 back and forth across the support surface (e.g., left and right in fig. 7) in a series of continuous pass processes (pass) after placing the abrasive tool 30 in contact with or on the object support surface of the object holder. Each respective pass may be in an opposite direction to the previous pass. According to the present disclosure, the passing process is referred to as relative movement between the tool 30 and the object holder from one edge or side (e.g., left) of the support surface or plane toward the opposite edge or side (e.g., right) of the support surface or plane. The number of passes is not limited and may depend on the material used to form the surface 32 and/or the body itself of the tool 30. According to one embodiment, at least 6 passes of the use tool 30 are used.

In one embodiment, the abrasive tool 30 may move in a substantially circular (e.g., circular) path along and across at least a portion of the support surface or plane of the object holder when the surface 32 is in contact with the support surface or plane of the object holder. For example, in one embodiment, the abrasive tool 30 may move in a loop as it is translated during the pass. In one embodiment, the abrasive tool 30 moves across a support surface or plane in a "Z" shaped pattern (e.g., randomly). In one embodiment, the abrasive tool 30 may rotate on an axis passing through and generally perpendicular to a central portion of the surface 32. In one embodiment, the rotation may be a partial rotation about an axis (e.g., a rotation less than or equal to about 90 degrees, a rotation less than or equal to about 60 degrees, a rotation less than or equal to about 45 degrees, or a rotation less than or equal to about 30 degrees). In one embodiment, the rotation (including partial rotation) is combined with linear motion (e.g., by a process or "Z" pattern). In one embodiment, to clean the edge of the support surface or plane of the object holder, the abrasive tool 30 may be moved (e.g., rotated to follow the contour of the edge) in an annular manner (e.g., circular) around the edge. In one embodiment, the annular movement may be repeated to create a concentric annular movement. In one embodiment, various combinations of these movement techniques may be used. In one embodiment, in any movement technique, the subsequent movement may at least partially overlap with the area covered by the previous movement.

In one embodiment, movement of the abrasive tool across the object holder may be performed manually by a person holding the abrasive tool 30. In one embodiment, movement of the abrasive tool 30 is performed by a machine, an automated system, or a robotic arm. For example, a robotic arm 34 (see fig. 7) may be used to move the abrasive tool 30. The abrasive tool 30 may be positioned on the end of the robotic arm 34, placed on the robotic arm 34, or captured by a device at the end of the arm 34 as follows: in such a way that the surface 32 can be positioned on and in contact with the object holder for movement across the object holder upon contact with the object holder.

The amount of force or pressure applied to the support surface using the abrasive tool 30 may vary. In one embodiment, the abrasive tool 30 is self-weight and only manual force is used to move the tool 30 across the surface of the object holder without adding a normal force relative to the support surface or plane of the object holder (e.g., zero normal force in the Z-direction; force is used only for lateral movement in a predetermined plane, e.g., in the X and/or Y directions). Thus, the force or pressure at the surface 32 and the support surface or plane of the object holder (or at least the projection 20) may be proportional to the weight/mass of the abrasive tool 30. In one embodiment, the force or pressure is greater or less than the force or pressure caused by the weight of the tool 30 multiplied by gravity. In one embodiment, the force or pressure is greater than the force or pressure caused by the weight of the tool 30 multiplied by gravity, e.g., greater than or equal to about 1.5 times, greater than or equal to about 2 times, greater than or equal to about 3 times, or greater than or equal to about 4 times the amount of the force. In one embodiment, the force or pressure is less than the force or pressure caused by the weight of the tool 30 multiplied by gravity, e.g., greater than about 1/2 of the full amount of the force but less than the full amount of the force. In one embodiment, a person may manually apply a force to the abrasive tool 30 as relative movement between the tool 30 and a support surface or plane of the object holder is provided. For example, in use of the machine or robotic arm 34, the machine or robotic arm may be designed to utilize the abrasive tool 30 to apply a force or pressure in a direction normal to a support surface or plane, such that the surface 32 is positioned against the support surface of the object holder, while moving the abrasive tool 30 across the support surface when the abrasive tool 30 is in contact with the support surface.

The weight of the abrasive tool 30 may depend on the material used to form the tool body and/or the substantially planar surface 32. In one embodiment, the weight of the abrasive tool 30 is selected from the range of about 80 grams to about 150 grams. In one embodiment, the weight of the abrasive tool 30 is selected from the range of about 100 grams to about 120 grams.

Although the above embodiments focus primarily on moving the abrasive tool 30, the relative movement between the abrasive tool 30 and the object holder may be accomplished in different ways. For example, in one embodiment, the object holder is configured to move relative to the abrasive tool 30 for abrasive action when the abrasive tool 30 is in contact with the object holder. In one embodiment, the abrasive tool 30 and the object holder are each configured to move when the abrasive tool 30 is in contact with the object holder for an abrasive action.

In one embodiment, the support surface of the object holder is wiped between a series of successive passes of the abrasive tool 30 relative to the object holder.

In one embodiment, a solvent is used when the polishing tool 30 is used to remove contaminants. In general, solvents can help to improve cleaning efficiency, reduce friction by acting as a lubricant, and reduce the risk of damaging the object holder. The use of solvents tends to reduce the force acting on the protrusions, allowing for smooth movement in the contact area between the surface 32 and the support surface of the object holder. The solvent also acts as a carrier in that the fluid can hold or suspend the material displaced by the surface 32 (instead of redeposit onto the object holder). The type of solvent used is not intended to be limiting. In one embodiment, the solvent is volatile. In one embodiment, the solvent is ethanol. In one embodiment, the solvent is methanol, acetone, and/or isopropanol. In one embodiment, water is used.

For example, in one embodiment, the contact area between the substantially planar surface 32 of the abrasive tool 30 and the support surface of the object holder is wetted with a solvent. In one embodiment, the solvent is applied directly to the surface 32 of the abrasive tool prior to positioning the abrasive tool in contact with the support surface. In one embodiment, the solvent is applied to the object holder (e.g., the support surface of the object holder) before the tool 30 and its surface 32 are positioned on and in contact with the support surface. In one embodiment, the solvent may be applied to the tool 30 prior to application to the object holder, and the solvent may be applied to the object holder prior to contact of the tool 30 with the object holder.

In addition to the use of the abrasive tool 30 described above, the abrasive tool 30 or another similar abrasive tool may be used on the object holder to roughen at least a portion of the support surface of the object holder. In one embodiment, the abrasive tool is used to roughen the top or upper surface of the protrusions (e.g., protrusions 20) of the object holder. In one embodiment, this use of the abrasive tool may be after the contaminants are removed from the support surface using, for example, tool 30. Increasing the surface roughness reduces the contact area of the support surface with the supported object (e.g., reduces the contact area of the protrusions 20 with the (bottom) surface of the substrate W), thereby improving friction with objects placed on the surface and thus, for example, reducing or eliminating loading grid errors.

In one embodiment, the roughening may be accomplished using different surfaces of the abrasive tool 30. For example, a backside surface (relative to surface 32) of the abrasive tool 30 may be used, wherein the backside surface has suitable characteristics for roughening. In one embodiment, a different abrasive tool 30 having a surface 32 with appropriate characteristics for roughening may be provided. Reference will be made hereinafter to the use of a second abrasive tool, but the same considerations may be applied to the backside surface (or other surface) of the abrasive tool 32 being used for cleaning.

The second abrasive tool for roughening may have the same characteristics and features as noted above with respect to the abrasive tool for cleaning 30. For example, the second abrasive tool for roughening may have a substantially planar abrasive surface configured to be positioned on and in contact with the object holder such that when the second abrasive tool is in contact with the support surface, there is relative movement between the second abrasive tool and the support surface of the object holder to roughen at least a portion of the support surface (e.g., roughen the top surface of the protrusions). In one embodiment, the roughened surface of the second abrasive tool for roughening is configured to be brought into contact with an upper surface of at least a protrusion (e.g., protrusion 20) of the object holder.

The second abrasive tool may have similar physical features as discussed in detail above with respect to the abrasive tool 30 for cleaning. For example, the second abrasive tool body and surface may be unitary or separate and formed of a homogeneous, non-natural (manufactured or manufactured) material. The shape and form of the tool and/or its surface contacting the object holder support surface (the tool's contact surface herein), lateral dimensions and thickness (such as shown and described above with reference to fig. 6) are also not limited and may be similar to the features noted above and therefore are not repeated here. Similarly, the second abrasive tool used for roughening may be utilized in a similar manner as discussed with respect to fig. 7 (e.g., moving through a series of passes and/or wetting with a solvent during use).

Furthermore, in one embodiment, at least the contact surface of the tool 30 is made of stone, granite, or ceramic material. In one embodiment, the surface comprises or consists essentially of a material selected from the group consisting of: alumina (Al) ₂ O ₃ ) Silicon carbide (SiC), silicon nitride (Si) ₃ N ₄ ) Aluminum nitride (AlN) and/or chromium nitride (CrN).

However, the difference from the abrasive tool 30 for cleaning is that the roughness of the contact surface of the second abrasive tool is different from the roughness of the surface 32 of the abrasive tool 30. For example, in one embodiment, the surface of the second abrasive tool can have a roughness of at least about 100nm Ra, or a roughness of at least about 150nm Ra, or a roughness of at least about 200nm Ra. In one embodiment, the roughness of the contact surface of the second abrasive tool is selected from the range of about 100nm Ra to about 3000nm Ra, the range of about 100nm to about 1200nm Ra, or the range of about 150nm to about 500nm Ra.

In one embodiment, the contact surface of the second abrasive tool falls within the same general flatness criteria as the surface 32 of the abrasive tool 30. In one embodiment, the flatness may be selected from the range of about 400nm to about 3000nm for a roughness taken from the range of about 100nm to 2000 nm. In one embodiment, the contact surface of the second abrasive tool falls within the same hardness criteria as the surface 32 of the abrasive tool 30.

Example

For testing purposes, two Al's with a roughness of 30nm Ra and a roughness of 200nm Ra were obtained, respectively ₂ O ₃ Stones (diameter 50mm, thickness 15 mm). Methanol is sprayed on top of the jig or support table. A 30nm stone is placed on top of the jig/table and, without any normal force applied, the stone moves from left to right, back to front to cover the entire area of the jig/table. After each two pass the 30nm stone was cleaned and kept wet with methanol. In general, the jig/table is globally stone-lapped (stoning) 6 times, and between each stone-lapping the jig is wiped with a cloth (tisue). Fig. 8 is a detailed close-up view of a protrusion with contamination on the jig/table before moving a 30nm Ra stone across the jig/table. After cleaning with 30nm Ra stones as described above, a significant amount of contaminants were removed from the protrusions as shown in fig. 9. The 30Ranm stone thus removed stubborn contaminants that could not be removed by standard cleaning methods, but did not significantly alter the flatness of the jig/table.

Then, in order to roughen the tops of the protrusions, 200nm Ra stone was applied in the same manner as 30nm Ra stone. This increases the number of scratches on the support surface of the top of the protrusion; thus, by effectively creating micro-protrusions on the protrusions when the substrate is placed on the protrusions, the contact area of the top of the protrusions with the substrate will be small. The coefficient of friction is lower due to the smaller contact area and loading grid errors may be reduced and/or eliminated.

After completion of these steps in this example, it was observed that the loading grid error of 8nm was reduced to 0.2nm. Furthermore, the friction after roughening with a stone of 200nm Ra is still sufficient to enable the protrusions to hold the substrate while being moved in a direction substantially parallel to the plane of the supporting surface of the protrusions.

As such, the present disclosure provides tools and methods for removing or cleaning refractory nm-scale or submicron-scale contaminants on an object holder surface (e.g., a protrusion top surface) without causing damage (e.g., rounding or breaking protrusions) or significantly altering the flatness of the object holder. Additionally or alternatively, the present disclosure provides tools and methods for roughening an object holder surface (e.g., a protrusion top surface) without causing damage (e.g., rounding or breaking the protrusions) or significantly altering the flatness of the object holder. The cleaning and/or roughening process is easy to implement in existing processes while still producing consistent results.

In one embodiment, the disclosed method and tool(s) may be used after standard cleaning step(s) of the object holder are achieved, including, for example, after large particles are removed from the surface of the object holder, after the object holder is wiped with a fabric or fiber cloth, after the object holder is stamped using, for example, a substrate (e.g., a substrate such as a silicon substrate typically used in device fabrication, and optionally the substrate may be treated with, for example, a coating to promote adhesion of contaminants to the substrate).

Although not shown in the figures, it should be understood that the disclosed one or more tools and/or methods may further be associated with one or more systems that are to be used concurrently or cooperatively with the cleaning methods and apparatus disclosed herein. For example, in one embodiment, a contaminant detection unit having one or more sensors therein may be provided to detect contaminants on the surface of the object holder and/or protrusions thereof. Further, in one embodiment, a controller may be provided for communicating with the contaminant detection unit to control the position of the detection portion of the contaminant detection unit and/or to sense or determine the amount of contaminant, e.g., based on the results of detection using the contaminant detection unit.

In one embodiment, a method of treating a support surface of a holder configured to hold an object is provided, the object holder comprising a plurality of protrusions extending from a body of the holder and configured to provide a support surface for the object, the method comprising: providing an abrasive tool comprising a substantially planar surface for positioning on and contacting an object holder; positioning a substantially planar surface of the abrasive tool in contact with a support surface of the object holder; and providing relative movement between the abrasive tool and at least a portion of the object holder to remove contaminants from the protrusion when the abrasive tool is in contact with the support surface, wherein the substantially planar surface of the abrasive tool has a roughness selected from the range of about 15nm Ra to about 50nm Ra, has a flatness of less than or equal to about 500nm, or has a roughness of at least about 15nm Ra and a flatness of less than or equal to about 500nm in a predetermined area of the substantially planar surface.

In one embodiment, the substantially planar surface of the abrasive tool has a roughness selected from about 15nm Ra to about 50nm Ra. In one embodiment, the substantially planar surface of the abrasive tool has a flatness of less than or equal to about 500nm within a predetermined area of the substantially planar surface. In one embodiment, the predetermined region has a flatness of less than or equal to about 150nm/cm per unit lateral dimension of the predetermined region within the predetermined region. In one embodiment, the method further comprises wetting the contact area of the substantially planar surface of the abrasive tool with a solvent with the support surface. In one embodiment, the wetting includes applying a solvent to a substantially planar surface of the abrasive tool prior to positioning the abrasive tool in contact with the support surface and/or the wetting includes applying a solvent to the support surface prior to positioning the abrasive tool in contact with the support surface. In one embodiment, the method further comprises positioning a contact surface of the abrasive tool or a contact surface of another abrasive tool other than the substantially planar surface in contact with the support surface of the object holder, wherein the contact surface is substantially planar; and providing relative movement between the contact surface and at least a portion of the object holder to roughen a portion of the support surface when the contact surface is in contact with the support surface, wherein the contact surface has a roughness of at least about 200nm Ra. In one embodiment, the contact surface has a flatness of less than or equal to about 500nm in a predetermined area of the contact surface. In one embodiment, the method further comprises wetting the contact surface and the contact area of the support surface with a solvent. In one embodiment, the wetting comprises applying a solvent to the contact surface prior to positioning the contact surface in contact with the support surface and/or the wetting comprises applying a solvent to the support surface prior to positioning the contact surface in contact with the support surface. In one embodiment, the surface of the abrasive tool in contact with the support surface comprises a material having a hardness greater than about 10 GPa. In one embodiment, the hardness is selected from the range of about 10GPa to about 30 GPa. In one embodiment, the relative movement includes sliding the abrasive tool back and forth across the support surface in a series of successive passes, each respective pass in the series being in a direction opposite to a previous pass in the series. In one embodiment, the method further comprises sliding the abrasive tool in a plurality of series of successive passes and wiping the support surface between each series of successive passes. In one embodiment, the relative movement is performed at least partially manually by a person. In one embodiment, the relative movement is performed at least in part by a machine or robotic arm. In one embodiment, the abrasive tool comprises stone or ceramic material.

In one embodiment, an abrasive tool is provided that is configured to be positioned on and in contact with an object holder, the object holder comprising a plurality of protrusions that provide a support surface for the object, the abrasive tool comprising a substantially planar surface arranged to abrade the support surface by relative movement between the substantially planar surface and the support surface to remove contaminants from the support surface, wherein the substantially planar surface of the abrasive tool has a roughness selected from a range of about 15nm Ra to about 50nm Ra, has a flatness of less than or equal to about 500nm, or has a roughness of at least about 15nm Ra and a flatness of less than or equal to about 500nm within a predetermined area of the substantially planar surface.

In one embodiment, the substantially planar surface of the abrasive tool has a roughness selected from the range of about 15nm Ra to about 50nm Ra. In one embodiment, the substantially planar surface of the abrasive tool has a flatness of less than or equal to about 500nm within a predetermined area of the substantially planar surface.

In one embodiment, an abrasive tool is provided that is configured to be positioned on and in contact with an object holder, the object holder comprising a plurality of protrusions that provide a support surface for an object, the abrasive tool comprising a substantially planar surface arranged to abrade the support surface by relative movement between the substantially planar surface and the support surface to roughen the support surface, wherein the substantially planar surface of the abrasive tool has a roughness selected from the range of about 200nm Ra to about 500nm Ra.

In one embodiment, the substantially planar surface of the abrasive tool has a flatness of less than or equal to about 500nm within a predetermined area of the substantially planar surface.

In one embodiment, there is provided a lithographic apparatus comprising: a patterning device support configured to support a patterning device; a patterning device configured to pattern the beam of radiation to form a patterned beam of radiation; a projection system configured to project the patterned radiation beam onto a target portion of the substrate; a substrate holder configured to hold a substrate; a system arranged to remove contaminants from a support surface of an object holder, the object holder comprising a plurality of protrusions providing a support surface for the object, the system comprising an abrasive tool comprising a substantially planar surface for positioning on and contacting the object holder, wherein the abrasive tool comprises a substantially planar surface having a roughness selected from a range of about 15nm Ra to about 50nm Ra, a roughness selected from a range of about 200nm Ra to about 500nm Ra, a flatness of less than or equal to about 500nm, or a flatness of at least about 15nm Ra and less than or equal to about 500nm in a predetermined area of the substantially planar surface.

In one embodiment, the object holder is a substrate holder or a patterning device support.

FIG. 10 is a block diagram illustrating a computer system 100 that may facilitate implementing the methods and processes disclosed herein. Computer system 100 includes a bus 102 or other communication mechanism for communicating information, and a processor 104 (or multiple processors 104 and 105) coupled with bus 102 for processing information. Computer system 100 may also include a main memory 106 (e.g., random Access Memory (RAM) or other dynamic storage device) coupled to bus 102 for storing or providing information and instructions to be executed by processor 104. Main memory 106 may be used for storing or providing temporary variables or other intermediate information during execution of instructions to be executed by processor 104. Computer system 100 may also include a Read Only Memory (ROM) 108 or other static storage device coupled to bus 102 for storing or providing static information or instructions for processor 104. A storage device 110, such as a magnetic disk or optical disk, may be provided and coupled to bus 102 for storing or providing information and instructions.

Computer system 100 may be coupled via bus 102 to a display 112, such as a Cathode Ray Tube (CRT) or flat panel or touch panel display, to display information to a computer user. Input device 114, which includes alphanumeric and other keys, may be coupled to bus 102 to communicate information and command selections to processor 104. Another type of user input device may be a cursor control 116 (e.g., a mouse, a trackball, or cursor direction keys) to communicate direction information and command selections to processor 104 and to control cursor movement on display 112. The input device typically has two degrees of freedom in two axes, a first axis (e.g., x) and a second axis (e.g., y), allowing the device to specify positions in a plane. A touch panel (screen) display may also be used as an input device.

According to one embodiment, portions of the processes described herein may be performed by computer system 100 in response to processor 104 executing one or more sequences of one or more instructions contained in main memory 106. Such instructions may be read into main memory 106 from another computer-readable medium, such as storage device 110. Execution of the sequences of instructions contained in main memory 106 causes processor 104 to perform the process steps described herein. One or more processors in a multi-processing arrangement may be employed to execute the sequences of instructions contained in main memory 106. In alternative embodiments, 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.

The term "computer-readable medium" as used herein refers to any medium that participates in providing instructions to processor 104 for execution. Such a medium may take many forms, including but not limited to, non-volatile media, and transmission media. Non-volatile media includes, for example, optical or magnetic disks (e.g., storage device 110). Volatile media includes dynamic memory (e.g., main memory 106). Transmission media includes coaxial cables, copper wire and fiber optics, including the wires that comprise bus 102. 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.

Various forms of computer readable media may be involved in carrying one or more sequences of one or more instructions to processor 104 for execution. For example, the instructions may initially be carried on a magnetic disk or memory of a remote computer. The remote computer can load the instructions into its dynamic memory and send the instructions over a communication path. Computer system 100 may receive data from the path and place the data on bus 102. Bus 102 transfers data to main memory 106, and processor 104 retrieves and executes instructions from main memory 106. The instructions received by main memory 106 may optionally be stored on storage device 110 either before or after execution by processor 104.

Computer system 100 may include a communication interface 118 coupled to bus 102. Communication interface 118 provides two-way data communication coupled to a network link 120, network link 120 being connected to a network 122. For example, the communication interface 118 may provide a wired or wireless data communication connection. In any such implementation, communication interface 118 sends and receives electrical, electromagnetic or optical signals that carry digital data streams representing various types of information.

Network link 120 typically provides data communication through one or more networks to other data devices. For example, network link 120 may provide a connection through network 122 to a host computer 124 or to data equipment operated by an Internet Service Provider (ISP) 126. ISP126 in turn provides data communication services through the world wide packet data communication network (now commonly referred to as the "Internet") 128. Network 122 and internet 128 both use electrical, electromagnetic or optical signals that carry digital data streams. Signals through the various networks and signals on network link 120 and through communication interface 118, which carry the digital data to and from computer system 100, are exemplary forms of carrier waves transporting the information.

Computer system 100 can send messages and receive data, including program code, through the network(s), network link 120 and communication interface 118. In the Internet example, a server 130 might transmit a requested code for an application program through Internet 128, ISP 126, network 122 and communication interface 118. One such downloaded application may provide code to implement, for example, the methods herein. The received code may be executed by processor 104 as it is received, or stored in storage device 110, or other non-volatile storage for later execution. The computer system 100 may obtain code in the form of a carrier wave.

Embodiments may be further described using the following clauses:

1. a method of treating a support surface of a holder configured to hold an object, the object holder comprising a plurality of protrusions extending from a body of the holder and configured to provide a support surface of the object, the method comprising:

providing an abrasive tool comprising a substantially planar surface for positioning on and contacting an object holder;

positioning a substantially planar surface of the abrasive tool in contact with a support surface of the object holder; and

Providing relative movement between the abrasive tool and at least a portion of the object holder when the abrasive tool is in contact with the support surface, to remove contaminants from the protrusions,

wherein the substantially planar surface of the abrasive tool has a roughness selected from the range of about 1nm Ra to about 100nm Ra, has a flatness of less than or equal to about 3000nm, or has a roughness of at least about 15nm Ra and a flatness of less than or equal to about 3000nm in a predetermined area of the substantially planar surface.

2. The method of clause 1, wherein the substantially planar surface of the abrasive tool has a roughness selected from the range of about 1nm Ra to about 100nm Ra.

3. The method of clause 1 or clause 2, wherein the substantially planar surface of the abrasive tool has a flatness of less than or equal to about 500nm in a predetermined area of the substantially planar surface.

4. The method of any of clauses 1-3, wherein the predetermined region has a flatness of less than or equal to about 150nm/cm per unit lateral dimension of the predetermined region within the predetermined region.

5. The method of any of clauses 1-4, further comprising wetting the contact area of the substantially planar surface of the abrasive tool with a solvent.

6. The method of clause 5, wherein the wetting comprises applying a solvent to the substantially planar surface of the abrasive tool prior to positioning the abrasive tool in contact with the support surface, and/or the wetting comprises applying a solvent to the support surface prior to positioning the abrasive tool in contact with the support surface.

7. The method of any one of clauses 1 to 6, further comprising:

positioning a contact surface of the abrasive tool other than the substantially planar surface or a contact surface of another abrasive tool in contact with the support surface of the object holder, wherein the contact surface is substantially planar; and

providing relative movement between the contact surface and at least a portion of the object holder when the contact surface is in contact with the support surface, roughening a portion of the support surface,

wherein the contact surface has a roughness of at least about 100nm Ra.

8. The method of clause 7, wherein the contact surface has a flatness of less than or equal to about 3000nm in a predetermined area of the contact surface.

9. The method of clause 7 or clause 8, further comprising wetting the contact surface and the contact area of the support surface with a solvent.

10. The method of clause 9, wherein the wetting comprises applying a solvent to the contact surface prior to positioning the contact surface in contact with the support surface, and/or the wetting comprises applying a solvent to the support surface prior to positioning the contact surface in contact with the support surface.

11. The method of any of clauses 1-10, wherein the surface of the abrasive tool in contact with the support surface comprises a material having a hardness greater than about 10 GPa.

12. The method of clause 11, wherein the hardness is selected from the range of about 10GPa to about 30 GPa.

13. The method of any of clauses 1-12, wherein the relative movement comprises sliding the abrasive tool back and forth across the support surface in a series of consecutive passes, each respective pass in the series being in a direction opposite to a previous pass.

14. The method of clause 13, further comprising sliding the abrasive tool in a plurality of series of consecutive passes and wiping the support surface between each series of consecutive passes.

15. The method of any one of clauses 1 to 14, wherein the relative movement is performed at least in part by a human hand.

16. The method of any one of clauses 1 to 15, wherein the relative movement is performed at least in part by a machine or a robotic arm.

17. The method of any of clauses 1-16, wherein the abrasive tool comprises stone or ceramic material.

18. An abrasive tool configured to be positioned on and in contact with an object holder, the object holder comprising a plurality of protrusions providing a support surface for an object, the abrasive tool comprising a substantially planar surface arranged to abrade the support surface by relative movement between the substantially planar surface and the support surface to remove contaminants from the support surface, wherein the substantially planar surface of the abrasive tool has a roughness selected from the range of about 1nm Ra to about 100nm Ra in a predetermined area of the substantially planar surface, has a flatness of less than or equal to about 3000nm, or has a roughness of at least about 15nm Ra and a flatness of less than or equal to about 3000nm in a predetermined area of the substantially planar surface.

19. The abrasive tool of clause 18, wherein the substantially planar surface of the abrasive tool has a roughness selected from about 15nm Ra to about 50nm Ra.

20. The abrasive tool of clause 18 or clause 19, wherein the substantially planar surface of the abrasive tool has a flatness of less than or equal to about 500nm within a predetermined area of the substantially planar surface.

21. An abrasive tool configured to be positioned on and in contact with an object holder, the object holder comprising a plurality of protrusions providing a support surface for an object, the abrasive tool comprising a substantially planar surface arranged to abrade the support surface by relative movement between the substantially planar surface and the support surface to roughen the support surface, wherein the substantially planar surface of the abrasive tool has a roughness selected from the range of about 100nm Ra to about 2000nm Ra.

22. The abrasive tool of clause 21, wherein the substantially planar surface of the abrasive tool has a flatness of less than or equal to about 3000nm within a predetermined area of the substantially planar surface.

23. A lithographic apparatus comprising:

a patterning device support configured to support a patterning device; the patterning device is configured to pattern the radiation beam to form a patterned radiation beam;

A projection system configured to project the patterned radiation beam onto a target portion of the substrate;

a substrate holder configured to hold a substrate;

a system arranged to remove contaminants from a support surface of an object holder, the object holder comprising a plurality of protrusions providing a support surface for the object, the system comprising an abrasive tool comprising a substantially planar surface for positioning on and contacting the object holder, wherein the substantially planar surface of the abrasive tool has a roughness selected from a range of about 1nm Ra to about 100nm Ra, a roughness selected from a range of about 200nm Ra to about 2000nm Ra, a flatness of less than or equal to about 3000nm, or a roughness of at least about 15nm Ra and a flatness of less than or equal to about 3000nm in a predetermined area of the substantially planar surface.

24. The apparatus of clause 23, wherein the object holder is a substrate holder or a patterning device support.

Although specific reference may be made in this text to the manufacture of ICs, it should be explicitly 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, flat panel displays, liquid Crystal Displays (LCDs), microelectromechanical systems (MEMS), thin film magnetic heads, and the like. Those skilled in the art will appreciate that any use of the terms "wafer" or "die" herein may be considered synonymous with the more general terms "substrate" or "target portion", respectively, in the context of such alternative applications.

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), an etching tool, a Chemical Mechanical Planarization (CMP) tool, 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 multiple times, for example, in order to create a multi-layer IC, such that the term substrate used herein refers to a substrate that already contains multiple processed layers.

While 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 (e.g. imprint lithography), and where the context allows, is not limited to optical lithography. In imprint lithography, a topography in a patterning device defines the pattern created on a substrate. The topography of the patterning device may be pressed into a layer of resist supplied to the substrate whereupon the resist is cured by applying electromagnetic radiation, heat, pressure or a combination thereof. The patterning device is moved out of the resist so that a pattern in the resist layer remains after the resist has cured.

The lithographic apparatus may also be of a type wherein the surface of the substrate is immersed in a liquid having a relatively high refractive index (e.g. water), so as to fill a space between the final element of the projection system and the substrate. The immersion liquid may be applied to other spaces in the lithographic apparatus (e.g., between the patterning device and the first element of the projection system). Immersion techniques are known in the art for increasing the numerical aperture of projection systems.

The terms "radiation" and "beam" used herein encompass all types of electromagnetic radiation, including Ultraviolet (UV) radiation (e.g. having a wavelength of 365nm, 248nm, 193nm, 157nm or 126 nm) and extreme ultra-violet (EUV) radiation (e.g. having a wavelength in the range of 5nm-20 nm), as well as particle beams (e.g. 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.

In the block diagrams, the illustrated components are depicted as discrete functional blocks, but the embodiments are not limited to systems in which the functionality as described herein is organized as a diagram. The functionality provided by each component may be provided by software or hardware modules that are organized differently than currently depicted, e.g., such software or hardware may be mixed, combined, replicated, split, distributed (e.g., within a data center or geographically dependent) or otherwise organized differently. The functions described herein may be provided by one or more processors of one or more computers executing code stored on a tangible, non-transitory machine-readable medium. In some cases, the third-party content delivery network may host some or all of the information communicated over the network, in which case the information (e.g., content) may be provided by sending instructions to retrieve the information from the content delivery network for the information to be supplied or otherwise provided.

Unless specifically stated otherwise as apparent from the discussion, it is appreciated that throughout the description, discussions utilizing terms such as "processing," "computing," "calculating," "determining," or the like, refer to the action or processes of a particular device (e.g., a special purpose computer or similar special purpose electronic processing/computing device).

The reader should understand that this application describes several inventions. Because the subject matter of these inventions may make the application process more economical, these inventions are combined into a single document rather than dividing these inventions into separate patent applications. However, the unique advantages and aspects of such an invention should not be mixed together. In some cases, embodiments address all of the drawbacks noted herein, but it is understood that the present invention is useful independently, and that some embodiments address only a subset of these issues, or provide other non-mentioned benefits, as will be apparent to one of ordinary skill in the art upon review of the present disclosure. Some of the inventions disclosed herein may not be presently claimed due to cost limitations, but may be claimed in later applications (e.g., continued application or by modifying the present claims). Similarly, neither the abstract nor the summary of the invention should be considered to contain a comprehensive list of all such inventions or all aspects of such inventions, for reasons of space limitation.

It should be understood that the description and drawings are not intended to limit the disclosure to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.

Modifications and alternative embodiments of various aspects of this invention will be apparent to those skilled in the art in view of this description. Accordingly, the description and drawings are to be construed as illustrative only and are for the purpose of teaching those skilled in the art the general manner of carrying out the invention. It is to be understood that the forms of the invention shown and described herein are to be taken as examples of embodiments. It will be apparent to those skilled in the art having the benefit of this description that elements and materials may be substituted for those illustrated and described herein, that parts and processes may be reversed or omitted, that certain features may be utilized independently, and that features of the embodiments or embodiments may be combined. Changes may be made in the elements described herein without departing from the spirit and scope of the invention as described in the following claims. The headings used herein are for organizational purposes only and are not meant to be used to limit the scope of the description.

As used throughout this application, the word "may" is used in a permissive sense (i.e., meaning having the potential to), rather than the mandatory sense (i.e., must). The words "include", "have" and the like mean including but not limited to. As used throughout this application, the singular forms "a," "an," and "the" include plural referents unless the content clearly dictates otherwise. Thus, for example, reference to "an" element includes a combination of two or more elements, although other terms and phrases (e.g., "one or more") may be used with respect to one or more elements. The term "or" is non-exclusive, i.e., includes "and" or "unless otherwise indicated. Terms describing conditional relationships (e.g., "responsive to X, Y," at X, Y, "" if X, Y, "" when X, Y "), etc., encompass causal relationships in which a leading cause is a necessary cause condition for a result, a leading cause is a sufficient cause condition for a result, or a leading cause is a contributing cause condition for a result, e.g.," state X occurs "when obtaining condition Y" with "X occurring only at Y" and "X occurs" commonly at Y and Z. Such conditional relationships are not limited to results obtained immediately after the predecessor because some results may be delayed, and in conditional statements, the predecessor is connected to its results, e.g., the predecessor is related to the likelihood of the result occurring. Unless otherwise indicated, a statement in which multiple attributes or functions are mapped to multiple objects (e.g., one or more processors perform steps A, B, C and D) encompasses all such attributes or functions being mapped to all such objects, and subsets of attributes or functions being mapped to subsets of attributes or functions (e.g., two processors each performing steps a-D, and in the case of processor 1 performing step a, processor 2 performing a portion of steps B and C, and processor 3 performing a portion of step C and step D). Further, unless otherwise stated, recitation of one value or action "based on" another condition or value encompasses both the case where the condition or value is the sole factor and the case where the condition or value is one of multiple factors. Unless otherwise indicated, the statement that "each" instance of a certain set has certain properties should not be construed to exclude the case that some of the otherwise identical or similar elements in a larger set do not have the properties, i.e., each does not necessarily mean all of each. References to a range selected from include the endpoints of the range.

In the foregoing description, any process, description, or block in the flow diagrams should be understood as representing modules, segments, or portions of code which include one or more executable instructions for implementing specific logical functions or steps in the process, and alternate implementations are included within the scope of the exemplary embodiments of the present advancement in which functions may be executed out of order from that shown or discussed, including substantially concurrently or in reverse order, depending upon the functionality involved, as would be understood by those reasonably skilled in the art.

While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the present disclosure. Indeed, the novel methods, apparatus and systems described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions, and changes in the form of the methods, devices, and systems described herein may be made without departing from the spirit of the disclosure. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the disclosure.

Claims

1. A method of treating a support surface of a holder configured to hold an object, the object holder comprising a plurality of protrusions extending from a body of the holder and configured to provide a support surface for the object, the method comprising:

Providing an abrasive tool comprising a planar surface for positioning on and in contact with the object holder;

positioning the planar surface of the abrasive tool in contact with the support surface of the object holder;

providing relative movement between the abrasive tool and at least a portion of the object holder to remove contaminants from the protrusions when the abrasive tool is in contact with the support surface, wherein the planar surface of the abrasive tool has a roughness selected from the range of 1nm Ra to 100nm Ra, has a flatness of less than or equal to 3000nm, or the planar surface has a roughness of at least 15nm Ra and has a flatness of less than or equal to 3000nm in a predetermined area of the planar surface;

providing a relative movement between a contact surface in contact with the support surface and at least a portion of the object holder to roughen a portion of the support surface, wherein the contact surface has a roughness of at least 100nm Ra.

2. The method of claim 1, wherein the planar surface of the abrasive tool has a roughness selected from the range of 1nm Ra to 100nm Ra.

3. The method of claim 1 or 2, wherein the planar surface of the abrasive tool has a flatness of less than or equal to 500nm within the predetermined area of the planar surface.

4. The method of claim 1 or 2, wherein the predetermined region has a flatness of less than or equal to 150nm/cm within the predetermined region per unit lateral dimension of the predetermined region.

5. The method of claim 1 or 2, further comprising: a contact area of the planar surface of the abrasive tool with the support surface is wetted with a solvent.

6. The method of claim 5, wherein the wetting comprises: applying the solvent to the planar surface of the abrasive tool prior to positioning the abrasive tool in contact with the support surface, and/or the wetting includes: the solvent is applied to the support surface prior to positioning the abrasive tool in contact with the support surface.

7. The method according to claim 1, wherein:

the contact surface comprises at least one of: a surface of the abrasive tool other than the planar surface, and a surface of another abrasive tool, wherein the contact surface is planar when the contact surface is in contact with the support surface.

8. The method of claim 7, wherein the contact surface has a flatness of less than or equal to 3000nm within a predetermined area of the contact surface.

9. The method of claim 7 or 8, further comprising: wetting the contact surface and the contact area of the support surface with a solvent.

10. The method of claim 9, wherein the wetting comprises: applying the solvent to the contact surface prior to positioning the contact surface in contact with the support surface, and/or the wetting comprises: the solvent is applied to the support surface prior to positioning the contact surface in contact with the support surface.

11. The method of claim 1 or 2, wherein the surface of the abrasive tool in contact with the support surface comprises a material having a hardness of greater than 10 GPa.

12. The method of claim 11, wherein the hardness is selected from the range of 10GPa to 30 GPa.

13. The method of claim 1 or 2, wherein the abrasive tool comprises stone or ceramic material.

14. An abrasive tool configured to be positioned on and in contact with an object holder, the object holder comprising a plurality of protrusions providing a support surface for an object, the abrasive tool comprising a planar surface arranged to abrade the support surface by relative movement between the planar surface and the support surface to remove contaminants from the support surface, wherein the planar surface of the abrasive tool has a roughness selected from the range of 1nm Ra to 100nm Ra, has a flatness of less than or equal to 3000nm in a predetermined area of the planar surface, or has a roughness of at least 15nm Ra and has a flatness of less than or equal to 3000nm in the predetermined area of the planar surface, and

The portion of the planar surface other than the predetermined region has a roughness of at least 100nm Ra and is arranged to abrade the support surface by relative movement between the planar surface and the support surface to roughen the support surface.

15. The abrasive tool of claim 14, wherein the planar surface of the abrasive tool has a roughness selected from the range of 15nm Ra to 50nm Ra.

16. The abrasive tool of claim 14 or 15, wherein the planar surface of the abrasive tool has a flatness of less than or equal to 500nm within the predetermined area of the planar surface.

17. A lithographic apparatus comprising:

a patterning device support configured to support a patterning device, the patterning device configured to pattern the beam of radiation to form a patterned beam of radiation;

a projection system configured to project the patterned radiation beam onto a target portion of a substrate;

a substrate holder configured to hold a substrate;

a system arranged to remove contaminants from a support surface of an object holder, the object holder comprising a plurality of protrusions providing a support surface for an object, the system comprising an abrasive tool comprising a planar surface for positioning on and in contact with the object holder, wherein the planar surface of the abrasive tool has a roughness selected from the range of 1nm Ra to 100nm Ra, has a roughness selected from the range of 200nm Ra to 2000nm Ra, has a flatness of less than or equal to 3000nm, or has a roughness of at least 15nm Ra and has a flatness of less than or equal to 3000nm in a predetermined area of the planar surface, and

18. The apparatus of claim 17, wherein the object holder is the substrate holder or the patterning device support.