Utility stage for photolithography apparatus and method - Patents.com

Abstract

An apparatus and method are disclosed that uses an in-system utility stage to provide servicing capabilities to the wafer table and other components within a photolithography system, where the utility stage can access multiple tools without having to open the enclosure that houses the utility stage, wafer table, and other components, thereby increasing throughput and reducing downtime.

Description

[Technical field]

[0001] [CROSS REFERENCE TO RELATED APPLICATIONS]

[0001] This application claims priority to U.S. Provisional Application No. 63 / 277,689, filed November 10, 2021, and is incorporated by reference in its entirety into this specification.

[0002] The subject matter of this disclosure relates to photolithographic manufacturing processes for integrated circuits. [Background technology]

[0003]

[0003] A lithographic apparatus is a machine that applies a desired pattern onto a substrate, usually onto a target portion of the substrate. Lithographic apparatus can be used, for example, in the manufacture of integrated circuits (ICs). In such a case, a patterning device, which can be a mask or a reticle, can be used to generate the circuit pattern formed on an individual layer of the IC. This pattern can be transferred onto a target portion (e.g. comprising part of one or more dies) on the substrate (e.g. a silicon wafer).

[0004]

[0004] Typically, transfer of the pattern is achieved by imaging onto a layer of radiation-sensitive material (resist) provided on the substrate. Typically, a single substrate will contain a network of adjacent target portions that are successively patterned. Conventional lithographic apparatus include so-called steppers, in which each target portion is irradiated by exposing the entire pattern onto the target portion at once, and so-called scanners, in which each target portion is irradiated by scanning the pattern with a radiation beam in a certain direction (the "scan" direction) while simultaneously scanning the substrate parallel or anti-parallel to this direction. It is also possible to transfer the pattern from the patterning device to the substrate by imprinting the pattern onto the substrate.

[0005]

[0005] Typically, the substrate will be supported by a substrate holder, called a wafer table, while it is being irradiated. The substrate may be held on the wafer table with an electrostatic chuck. The substrate holder may be provided with support elements that minimize the contact area between the substrate and the substrate holder. The support elements on the surface of the substrate holder may be called burls or protrusions. The support elements are usually regularly spaced (e.g. in a uniform array), have a uniform height and define a generally very flat support surface on which the substrate can be positioned.

[0006]

[0006] The support elements typically extend substantially perpendicularly from the surface of the substrate holder. In operation, the back surface of the substrate is supported on the support elements in a position substantially perpendicular to the propagation direction of the projection beam, close to the body surface of the substrate holder. Thus, the top of the support elements (i.e. the support surface), and not the body surface of the substrate holder, defines the effective support surface for the substrate.

[0007]

[0007] To avoid overlay errors during projection of the patterned radiation beam onto the substrate, it is desirable for the top surface of the substrate to be flat. Irregularities in the support surface of the substrate support may lead to unevenness in the top surface of the substrate. It is therefore desirable to avoid unevenness in the substrate support.

[0008]

[0008] Irregularities in the support surface may be caused by differences in the height of the material that constitutes the support elements themselves. This is usually the case when a new substrate holder is manufactured. The irregularities may be the result of differences between the heights of the support elements or differences in the back surface of the substrate holder. These elements are therefore carefully made flat. Nevertheless, it has been found that irregularities may also occur when the substrate table (and any other element) is assembled or installed. Similar problems may arise for holders for other articles that need to be supported on a clearly defined surface across the beam path, such as reflective or transmissive patterning devices.

[0009]

[0009] Another cause of unevenness in the wafer supporting surface is contaminants in the form of particles on the lithography tool wafer table which can cause "hot spots", which are areas on the wafer that are not flat relative to the chuck of the wafer table due to particles trapped between the wafer and the wafer table. As mentioned above, wafers processed through a stepper are electrostatically clamped to the wafer table. Thus, the presence of particles on the backside of the wafer will locally deform the front side of the wafer, leading to the unevenness mentioned above (part of the front side being locally out of focus). Contaminants on the wafer table can lead to machine downtime of several days.

[0010]

[0010] The usual procedure to remove the irregularities is to take the tool offline and open the tool to clean the wafer table, or to "stone" the wafer table with the tool to break up or remove particles or to restore planarity to the wafer support surface. Either procedure can prevent critical tool availability for many hours. These uneven areas have traditionally been removed by grinding the surface of the wafer table with an abrasive disk to make the surface flat or to remove contaminants. The abrasive can be, for example, granite or ceramic. By using a material such as granite, these abrasive disks are called "stones" and the procedure is called "stoning".

[0011]

[0011] Some lithography machines have dual chucks that move two wafers simultaneously. While one wafer is being exposed, the position of the other wafer is measured by the machine's metrology sensors. Some lithography tools have an automatic measurement feature that identifies hot spots and powers down the tool until the cause of the hot spots is addressed.

[0012]

[0012] Some tools also have an optional automatic chuck cleaner, where a cleaning stone in a holder under the scanner frame cleans the chuck as it moves under the stone. Using such technology, the time to clean a single spot can be reduced to about one minute, and the time to clean the entire chuck can be reduced to about 20 minutes. By comparison, manually cleaning hot spots by lowering and raising the tool can take one to three hours.

[0013]

[0013] Although these techniques have significantly increased throughput, they still require opening the housing housing the wafer table if one wishes to use a stone other than the one currently installed. This results in increased downtime. Even greater throughput advantages could be obtained if the stone could be replaced without opening the housing housing the wafer table. This also applies to other operations that normally require opening the housing. It is in these circumstances that the need for the presently disclosed subject matter arises. Summary of the Invention

[0014]

[0014] The following presents a simplified summary of one or more embodiments in order to provide a basic understanding of the invention. This summary is not an extensive overview of all contemplated embodiments, and is not intended to identify key or critical elements of all embodiments or to delineate the scope of any or all embodiments. Its sole purpose is to present some concepts related to one or more embodiments in a simplified form as a prelude to the more detailed description that is presented later.

[0015] According to one aspect of the embodiment, having an "in-system" utility stage designed to transport objects in addition to wafers for processing allows a given arrangement to change tools such as stones in situ. Here and elsewhere, the term "in-system" is used to mean that the device or function being referred to is one that operates without the need to open the enclosure that houses the wafer table. According to another aspect of the embodiment, various tools are stored in a tool store within the system, and the utility stage can retrieve tools from the tool store and load the tools into a utility device, such as a cleaner, within the system.

[0016] According to another aspect of an embodiment, a photolithography apparatus is disclosed that includes a housing, at least one object table disposed within the housing and adapted to move between a plurality of positions within the housing, a utility device disposed within a utility zone within the housing, and a utility stage disposed within the housing and adapted to move from a park position to the utility zone, the utility stage adapted to carry at least one tool from the park position to the utility zone.

[0017]

[0017] The photolithography apparatus may further include a tool storage located in the housing adjacent to the standby position and a plurality of tools stored in the tool storage, and the utility stage is adapted to unload the first tool from the tool storage, transport the first tool to the utility device, and load the first tool to the utility device. The object table may include a wafer table, the utility device may include a wafer table cleaning tool located at the utility position, and the first tool may include a first cleaning stone.

[0018]

[0018] The utility stage may be further adapted to unload the first tool from the utility device, transport the first tool to the tool store, and load the first tool to the tool store. The at least one object table may include a first wafer table and a second wafer table. The utility stage may include an extendable robot arm arranged to position the utility stage.

[0019]

[0019] According to another aspect of an embodiment, a photolithography apparatus is disclosed that includes a housing and a first wafer table disposed within the housing and adapted to move between a plurality of coplanar positions within the housing, the plurality of coplanar positions including a load position at which a first wafer handler loads a wafer of semiconductor material onto the first wafer table, a measurement position at which a wafer on the first wafer table can be measured, an exposure position at which a wafer on the first wafer table can be exposed to patterned radiation, and an unload position at which the wafer on the first wafer table is unloaded by a second wafer handler. The housing further houses a second wafer table adapted to move between a plurality of coplanar positions within the housing, the plurality of coplanar positions including a load position at which the first wafer handler loads a wafer of semiconductor material onto the second wafer table, a measurement position at which a wafer on the second wafer table can be measured, an exposure position at which a wafer on the second wafer table can be exposed to patterned radiation, and an unload position at which a wafer on the second wafer table is unloaded by the second wafer handler, wherein the second wafer table is moved to avoid interfering with movement of the first wafer table, and the first wafer table is moved to avoid interfering with movement of the second wafer table.

[0020]

[0020] The housing further accommodates a utility device positioned within the utility zone and adapted to perform a utility operation on the wafer, and a utility stage adapted to move from a standby position to the utility zone, the utility stage adapted to carry at least one tool from the standby position to the utility zone and moved and positioned to avoid interfering with movement of the first wafer table and the second wafer table.

[0021]

[0021] The photolithography apparatus may further include a tool storage located within the housing adjacent to the standby position and a plurality of tools stored within the tool storage, and the utility stage is adapted to unload a first tool from the tool storage, transport the first tool to the utility device, and load the first tool to the utility device. The utility device may include a wafer table cleaning tool located within the utility zone, the first tool including a first cleaning stone. The plurality of tools stored in the tool storage may include a plurality of cleaning stones.

[0022]

[0022] The first tool may include a sticky wafer and the utility device may include a wafer table cleaning tool adapted to press the sticky wafer against a wafer receiving surface of the wafer table. The first tool may include a spiked wafer and the utility device may include a wafer table cleaning tool adapted to press the spiked wafer against a wafer receiving surface of the wafer table.

[0023]

[0023] The utility stage may be further adapted to unload the first tool from the utility device, transport the first tool to the tool store, and load the first tool to the tool store. The utility stage may include an extendable robotic arm.

[0024]

[0024] According to another aspect of an embodiment, a method of operating a photolithography apparatus including a housing, a first wafer table disposed within the housing and adapted to move between a plurality of coplanar positions within the housing, a second wafer table disposed within the housing and adapted to move between a plurality of coplanar positions within the housing, a utility device disposed within a utility zone inside the housing and adapted to perform a utility operation on the wafer, and a utility stage disposed within the housing and adapted to move from a standby position to the utility zone, the utility stage being adapted to carry at least one tool from the standby position to the utility zone, the method being disclosed including positioning the first wafer table at a first neutral position where the first wafer table does not interfere with movement of the utility stage from the standby position to the utility zone, positioning the second wafer table at a second neutral position where the second wafer table does not interfere with movement of the utility stage from the standby position to the utility zone, and moving the utility stage from the standby position to the utility zone.

[0025]

[0025] When the utility stage is in the standby position, the utility stage may unload the tool from the tool storage. The first tool may be one of the multiple tools stored in the tool storage. When the utility stage is in the utility zone, the utility stage may load the tool into a utility device. When the utility stage is in the standby position, the utility stage may unload the tool from the tool storage, move to the utility zone, and load the tool into a utility device in the utility zone.

[0026]

[0026] The method may further include unloading the first tool from the utility stage in the utility zone using the utility stage, moving the utility stage to a standby position, unloading the first tool from the utility stage and loading the first tool into the tool storage section, unloading the second tool from the tool storage section and loading the second tool into the utility stage, moving the utility stage to the utility zone, and loading the second tool into the utility device using the utility stage.

[0027]

[0027] The utility device may include a wafer table cleaning tool disposed within the utility zone, and a first tool may include a first cleaning stone. The first tool may include a sticky wafer, and the utility device may include a wafer table cleaning tool adapted to press the sticky wafer against a wafer receiving surface of the wafer table.

[0028]

[0028] The first tool may include a spiked wafer, and the utility device may include a wafer table cleaning tool adapted to press the spiked wafer against a wafer receiving surface of the wafer table.

[0029]

[0029] The photolithography apparatus may include a lens, the first tool may include a lens cleaning device, and the utility stage may be adapted to move to the lens and to position the lens cleaning device to clean the lens.

[0030] Further embodiments, features, and advantages of the subject matter of the present disclosure, as well as the structure and operation of the various embodiments, are described in detail below with reference to the accompanying drawings. [Brief description of the drawings]

[0031] [Figure 1]

[0031] FIG. 1 is a schematic, not to scale, illustration of the overall broad concept of a photolithography system. [Diagram 2]

[0032] 1 is a schematic, not to scale, diagram of the overall broad concept of a wafer transport system for a photolithography system; [Figure 3A]

[0033] FIG. 2 is a schematic, not-to-scale, plan view of a wafer transport system for a photolithography system in a first configuration. [Figure 3B]

[0034] FIG. 2 is a schematic, not-to-scale, plan view of a wafer transport system for a photolithography system in a second configuration. [Figure 4A]

[0035] 1 is a schematic, not-to-scale, plan view of a wafer transport system according to an aspect of the disclosed subject matter in a first configuration. [Figure 4B]

[0036] FIG. 2 is a schematic, not-to-scale, plan view of a wafer transport system according to an aspect of the disclosed subject matter in a second configuration. [Figure 4C]

[0037] FIG. 13 is a schematic, not-to-scale, plan view of a wafer transport system according to an aspect of the disclosed subject matter in a third configuration. [Figure 5A]

[0038] FIG. 1 is a perspective view of a cleaning tool used as a utility device in accordance with an aspect of the disclosed subject matter. [Figure 5B]

[0039] FIG. 1 is a cross-sectional view of a cleaning tool used as a utility device in accordance with an aspect of the disclosed subject matter. [Figure 5C]

[0040] FIG. 1 is a partial perspective view of a tool store in accordance with an aspect of the disclosed subject matter. [Figure 6A]

[0041] 1 is a flow chart illustrating certain aspects of a method of using a utility stage in a wafer transport system in accordance with aspects of the disclosed subject matter. [Figure 6B]

[0042] 1 is a flow chart illustrating certain aspects of a method of using a utility stage in a wafer transport system in accordance with aspects of the disclosed subject matter. [Figure 7]

[0043] FIG. 1 is a functional block diagram of a control system for a wafer transport system in accordance with aspects of an embodiment of the disclosed subject matter.

[0032]

[0044] Further features and advantages of the disclosed subject matter, as well as the structure and operation of various embodiments of the disclosed subject matter, are described in detail below with reference to the accompanying drawings. It should be noted that the applicability of the disclosed subject matter is not limited to the specific embodiments described herein. Such embodiments are presented herein for illustrative purposes only. Additional embodiments will be apparent to those skilled in the art based on the teachings herein. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0033]

[0045] Various embodiments are now described with reference to the drawings. In the following description, for purposes of explanation, numerous specific details are set forth in order to facilitate a thorough understanding of one or more embodiments. It will be apparent, however, that in some or all cases, any of the embodiments described below can be implemented or performed without employing the specific design details described below. In other instances, well-known structures and devices are shown in block diagram form in order to facilitate describing one or more embodiments. This summary is not an extensive overview of all possible embodiments, and is not intended to identify key or critical elements of all embodiments or to delineate the scope of any or all embodiments.

[0034]

[0046] The embodiments of the present invention may be implemented in hardware, firmware, software, or any combination thereof. The embodiments of the present invention may also be implemented as instructions that can be stored on a machine-readable medium and read and executed by one or more processors. A machine-readable medium may include any mechanism for storing or transmitting information in a form readable by a machine (e.g., a computing device). For example, a machine-readable medium may include a read-only memory (ROM), a random access memory (RAM), a magnetic disk storage medium, an optical storage medium, a flash memory device, or an electrical, optical, acoustic, or other form of propagated signal (e.g., carrier wave, infrared signal, digital signal, etc.). Furthermore, firmware, software, routines, instructions may be described herein as performing some operation or causing some operation to be performed. However, it should be understood that such description is merely for convenience and that such operations are in fact performed by a computing device, processor, controller, or other device executing the firmware, software, routines, instructions, etc.

[0035]

[0047] By way of introduction, Figure 1 illustrates diagrammatically an embodiment of a lithographic apparatus LA that may be included in and / or associated with the present systems and / or methods. The lithographic apparatus LA includes an illumination system (illuminator) IL configured to condition a radiation beam B. As used herein, the terms "radiation" and "beam" encompass all types of electromagnetic radiation, including ultraviolet (UV) or deep ultraviolet (DUV) (e.g. having a wavelength of 365 nm, 248 nm, 193 nm, 157 nm or 126 nm), and extreme ultraviolet (EUV) (e.g. having a wavelength in the range of 5-20 nm), as well as particulate beams such as ion beams and electron beams.

[0036]

[0048] The lithographic apparatus LA further comprises a support structure (e.g., mask table) MT constructed to support a patterning device (e.g., mask) MA and coupled to a first positioner PM configured to accurately position the patterning device according to certain parameters, and one or more substrate tables (e.g., wafer tables) WT (in one example, two wafer tables, WTa and WTb) configured to hold a substrate (e.g., resist-coated wafer) W. Each wafer table is mechanically coupled to a respective positioner PW configured to accurately position the substrate on a wafer support surface WSS according to certain parameters. As used herein, either the mask table or the wafer table may be considered as an object table.

[0037]

[0049] The lithographic apparatus LA further comprises a projection system (e.g. a refractive projection lens system) PS configured to project a pattern imparted to the radiation beam B by the patterning device MA onto a target portion C (e.g. comprising one or more dies, often referred to as a field) of the substrate W. The projection system is supported on a reference frame RF.

[0038]

[0050] As depicted, the lithographic apparatus may be of a transmissive type (e.g. employing a transmissive mask) or it may be of a reflective type (e.g. employing a programmable mirror array as referred to above, or employing a reflective mask).

[0039]

[0051] The illuminator IL receives a radiation beam from a radiation source SO. The source and the lithographic apparatus may be separate entities, for example when the source is an excimer laser. In such cases the source is not considered to form part of the lithographic apparatus and the radiation beam is delivered from the source SO to the illuminator IL using a beam delivery system BD, which may include, for example, suitable directing mirrors and / or beam expanders. 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. If the source is of a type that produces EUV radiation, typically reflective optics will be used.

[0040]

[0052] The illuminator IL may include an adjuster AD configured to adjust the (angular / spatial) intensity distribution of the beam. In addition, the illuminator IL typically includes various other components, such as an integrator IN and a condenser CO. Illumination systems may include various types of optical components to direct, shape or control the radiation. Thus, the illuminator IL provides a conditioned radiation beam B, which has a desired uniformity and intensity distribution in its cross-section.

[0041]

[0053] The support structure MT supports and holds the patterning device MA using mechanical, vacuum, electrostatic or other clamping techniques. As used herein, the term "patterning device" should be interpreted broadly to refer to any device that can be used to impart a pattern in a target portion of a substrate. As mentioned above, the patterning device MA may be transmissive or reflective. Examples of patterning devices include masks, programmable mirror arrays, and programmable LCD panels.

[0042]

[0054] The lithographic apparatus may be of a type having two or more tables (e.g. two or more substrate tables WTa, WTb, two or more patterning device tables, a substrate table WTa and a table WTb below the projection system without a substrate, which may be used only to facilitate measurement and / or cleaning etc.). In such a "multi-stage" machine, the additional tables may be used in parallel, or preliminary steps may be carried out on one or more tables whilst another one or more tables are used for exposure. For example, alignment measurements using alignment sensors AS and / or level (height, tilt etc.) measurements using level sensors LS may be made.

[0043]

[0055] The lithographic apparatus may also be of a type in which at least a portion of the substrate may be covered by a liquid having a relatively high refractive index (eg, water), so as to fill a space between the projection system and the substrate.

[0044]

[0056] In operation of the lithographic apparatus, a radiation beam is conditioned and provided by an illumination system IL. The radiation beam B is incident on a patterning device (e.g. mask) MA, which is held on a support structure (e.g. mask table) MT, and is patterned by the patterning device. After passing through the patterning device MA, the patterned radiation beam B passes through a projection system PS, which focuses the beam onto a target portion C of a substrate W. Using a respective positioner PW and position sensor IF (e.g. an interferometric device, a linear encoder, a 2D encoder, or a capacitive sensor), the substrate tables WTa or WTb can be accurately moved, for example, to position different target portions C in the path of the radiation beam B. Similarly, another positioner 305 and another position sensor (not explicitly shown in FIG. 1 ) can be used to accurately position the patterning device MA with respect to the path of the radiation beam B, for example after mechanical retrieval from a mask library or during a scan.

[0045]

[0057] The patterning device MA and substrate W may be aligned using patterning device alignment marks M1 and M2 and substrate alignment marks P1 and P2. Although in the illustrated example the substrate alignment marks occupy dedicated target portions, the substrate alignment marks may be located in spaces between the target portions (these are known as scribe-lane alignment marks). Similarly, in cases where more than one die is provided on the patterning device MA, the patterning device alignment marks may be located between the dies.

[0046]

[0058] The substrates described herein may be processed, before or after exposure, in, for example, a track (a tool that typically applies a layer of resist to a substrate and develops the exposed resist), a metrology tool, or an inspection tool. Where applicable, the disclosure herein may be applied to such and other substrate processing tools. Furthermore, a substrate may be processed multiple times, for example to create a multi-layer IC, and thus the term substrate as used herein may refer to a substrate that already includes one or more processing layers.

[0047]

[0059] Figure 2 is a more detailed schematic diagram of the dual wafer table scanner 200. A laser 210 generates a beam of radiation. One or more beam correctors 220 (three in the example of Figure 2) correct the direction of incidence of the beam. An energy controller 230 controls the energy that ultimately reaches the silicon wafers 320, 340.

[0048]

[0060] The beam enters the enclosure 240, supported by shock absorbers 380 that isolate the interior of the enclosure 240 and reduce interference from external vibrations. Within the enclosure 240, the beam is acted upon by a beam shaper 250 that sets the beam into various shapes such as circles, rings, etc. The beam then enters a shutter device 260 that prevents the beam from irradiating the wafer 320, 340 when no exposure is required. The beam is then split by a beam splitter 270 that directs a portion of the beam to an energy detector 280, which detects if the final incident energy of the beam meets the exposure requirements of the current process recipe and provides feedback to the energy controller for adjustment.

[0049]

[0061] The other portion of the beam is directed to a mask 290 positioned on a reticle stage 300 that controls the position and movement of the mask 290. The mask 290 patterns the beam, and the patterned beam then passes through an objective lens 310 that corrects for optical errors and proportionally demagnifies the pattern. The beam then reaches a silicon wafer 320 that is covered with photoresist that transfers the pattern in the beam to the surface of the silicon wafer 320. The silicon wafer 320 is positioned on a first wafer table 330 that positions and moves the wafer 320 over a substrate support surface 335. The wafer tables 330, 350 may or may not be in physical contact with the substrate support surface 335.

[0050]

[0062] If the scanner 200 is of the type having dual wafer tables, as in this example, the second wafer 340 may be positioned on the second wafer table 350. In the portion of operation shown in Figure 2, the second wafer 340 is positioned to be measured by the measurement devices 360, 370.

[0051]

[0063] FIG. 3A is a schematic plan view of substrate support surface 335 showing two wafer tables 330 and 350 and wafer handlers 400 and 410 for loading and unloading wafers, such as wafer 320. As indicated by the horizontal and vertical arrows, each wafer table can move horizontally and vertically in the plane of the figure. More specifically, each wafer table is connected to an arm, with wafer table 330 connected to arm 337 and wafer table 350 connected to arm 357. Each wafer table can move horizontally along the length of its arm to access positions across the width of substrate support surface 335. Each arm is connected to a respective rail, with arm 337 connected to rail 339 and arm 357 connected to rail 359. The rails allow each arm / wafer table to move vertically to various positions along the length of substrate support surface 335 in the plane of the figure. In the configuration of FIG. 3A, wafer table 330 is positioned at an exposure position EP where a wafer can be exposed to patterned radiation. Wafer table 350 is positioned at measurement position MP where the alignment, etc. of the wafer can be checked.

[0052]

[0064] 3A also shows wafer handler 400 configured as a wafer loader and positioned to load a wafer onto a wafer table, and wafer handler 410 configured as a wafer extractor and positioned to extract a wafer from the wafer table. As shown, wafer handler 400 can be extended to reach a wafer loading position LP, and wafer handler 410 can be extended to reach a wafer unloading position UP, as indicated by the diagonal arrows.

[0053]

[0065] 3B shows a configuration in which wafer handler 400 moves wafer table 350 to a load position LP where wafer 320 can be loaded onto wafer table 350. This position is also reachable by wafer table 330. Adjacent to the side of load position LP is an unload position UP, which is also reachable by both wafer tables 330 and 350, where wafer handler 410 can unload a wafer from either wafer table 330 or 340.

[0054]

[0066] In summary, the wafer handlers 400 and 410 are extendable and operable to place a new wafer on one of the wafer tables 330, 350 or remove a processed wafer from one of the wafer tables 330, 350. Each wafer table 330, 350 can reach a load position LP, an unload position UP, a measurement position MP, and an exposure position EP.

[0055]

[0067] As mentioned above, if the top surface of the wafer is not flat, manufacturing defects can occur. One cause of the non-flatness of the wafer surface is particulate contaminants that build up on the surface of the wafer support table. It is therefore desirable to have the ability to periodically remove these contaminants. It is also desirable to be able to perform this wafer table surface cleaning procedure without opening the enclosure that houses the wafer table. If the scanner needs to be opened, this can result in the penalty of downtime on the order of hours or days. Therefore, systems exist that provide in-situ wafer table cleaning where the wafer table can be cleaned within the system.

[0056]

[0068] While such systems are effective in reducing machine downtime, it may be desirable to be able to replace stones required for a particular cleaning or other polishing application without opening the enclosure. In other words, it may be desirable to use stones that have different grades or other characteristics than those currently in the wafer table cleaning tool. Thus, according to one aspect of an embodiment, a robot utility stage is positioned to move along a portion of the wafer table support surface. The robot utility stage can access a location on the wafer table cleaning device to replace the current stone with a stone appropriate for the desired wafer table maintenance operation.

[0057]

[0069] In the following examples, the use of this utility stage is described as the third stage of a dual stage scanning system, although it will be understood that the benefits of the present invention can also be obtained in a single stage scanning system. Also, while described herein with respect to a wafer processing system, this is merely to provide a specific example to facilitate clarity of explanation. This is a non-limiting example, and one of ordinary skill in the art will readily appreciate that the principles described herein also apply to other parts of a photolithography system that would benefit from the incorporation of a utility stage, such as an in-system robot that currently includes two arms to present a mask or reticle to the reticle stage 300.

[0058]

[0070] For example, in a dual scan stage system, the utility stage 500 may have a park position PP between the two wafer handlers 400, 410, as shown in FIG. 4A. The utility stage 500 may then be moved to a utility zone UZ having one or more utility devices 450, such as a cleaner, to a vertically central portion of the substrate support surface 335 while the wafer tables 330, 350 are in positions that do not impede the movement of the utility stage 500. For example, as shown in FIG. 4B, the utility stage 500 may take a position to the right of the substrate support surface 335 when the wafer table 330 is in an exposure position and the wafer table 350 is in a loading position. The utility stage 500 may occupy a vertically central position to the left of the substrate support surface 335 when the wafer stage is in the configuration shown in FIG. 4C. The utility stage 500 may be moved to various positions by an extendable robot arm 525 as shown, or by other means.

[0059]

[0071] As shown, the utility stage 500, in a parked position PP between the wafer handlers 400, 410, may access a tool store 520, such as a carousel or cassette, that holds various tools. According to one aspect of the embodiment, the tools may be stones with varying characteristics, such as grain size or composition. The utility stage 500 may exchange stones with the tool store 520, or retrieve stones from the tool store 520 if no stones are already loaded on the utility stage 500, and then move to a position where the utility stage 500 may exchange the stone it is carrying with a stone currently in a cleaning station in the utility zone UZ. In this way, the most appropriate stone can be used while avoiding opening the enclosure. The stones may be any of a variety of types and varieties, such as for cleaning, repairing burl tops, enhancing flatness, cleaning photoresist, removing carbon contaminants, imprinting structures, etc. For example, the stones may include two roughness measurement stones, four flatness stones, and one photoresist cleaning stone. It can be stored in tool storage 520 along with other cleaning tools such as SiO etch processing tools and / or burl-to-burl cleaning wands.

[0060]

[0072] Generally, the description herein is of a large tool (i.e., designed to interact with a clamp or an entire wafer) as an example, but it will be understood that the concepts described herein apply to smaller tools as well. For example, FIG. 4B also shows an optical component 540, such as a lens. This may be an objective lens of a wafer alignment metrology unit. Over time, such a lens may become contaminated by gaseous substances released from the photoresist on the wafer. One of the tools that the utility stage 500 may retrieve from the tool store 520 may be a lens cleaning device that the utility stage may carry to a lens and use to clean the lens.

[0061]

[0073] According to one aspect of the embodiment, as shown in FIG. 5A, the utility device 450 may be a cleaning station including an element 600 arranged to cause relative motion (rotation, reciprocation, or a combination thereof) between a stone 610 and an upper surface (chuck) of a wafer table 620. As shown in FIG. 5B, the upper surface 620 is provided with protrusions or burls 630 as described above, which define a contact surface with a wafer 610 placed on the wafer table 620. The element 600 may be located within a utility zone UZ. The utility stage 500 may travel to the element 600 to unload the stone 610, which may then be replaced with another stone in the tool store 520, which the utility stage 500 may then transport to and load into the element 600.

[0062]

[0074] Tool storage 520 may take any of several forms to aid in the exchange of wafers with utility stage 500. FIG. 5C shows one possible configuration in which tools 610 in the example stone are positioned adjacent to one another in a cassette frame 640. Tools 650 may be any of the other types of tools mentioned above, such as flatness stones, photoresist cleaning stones, SiO etch processing tools, inter-burr cleaning wands, lens cleaners, etc. It will be apparent to one of ordinary skill in the art that other tools and other configurations of tool storage are possible.

[0063]

[0075] According to another aspect of the embodiment, a method of using a utility stage in a system is disclosed. Referring to FIG. 6A, in step S10, the utility stage is placed in a standby position in an enclosure. The enclosure also includes one or more wafer tables. In step S20, the utility stage loads a tool from a tool store located in the enclosure. If the utility stage already has a tool, it exchanges the tool with the tool store in the system. In step S30, the utility stage is placed in a utility position where a utility device, such as a wafer table cleaning tool, is also located. In step S40, the utility stage loads the tool into the utility device. In step S50, the utility stage is returned to the standby position.

[0064]

[0076] Of course, if a tool is already loaded on the utility device, the steps described here are preceded by a series of steps in which the utility stage moves to the utility device, removes the tool, and places it in the tool store. Such a procedure is shown in FIG. 6B. In step S60, the utility stage is placed in the utility zone. In step S70, the utility stage unloads the current tool from the utility device. In step S80, the utility stage is moved to a standby position. In step S90, the utility stage unloads or has unloaded the tool it is carrying and stores it in the tool store. In step S100, the utility stage loads a new tool from the tool store. In step S110, the utility stage is placed in the utility zone. In step S120, the utility stage loads the new tool into the utility device. Then, in step S130, the utility stage is relocated to the standby position.

[0065]

[0077] Adding such a "third chuck" can also add in-system performance / calibration / maintenance capabilities to the system. Thus, according to one aspect of an embodiment, the utility stage 500 can also carry as a tool a calibration sample loaded from the tool store 520. The utility stage 500 can also carry as a tool an instrument to inspect the wafer tables 330, 350 for damaged burls. Thus, the tool 650 can be one of these tools.

[0066]

[0078] Tool storage 520 may be supplied with a special dummy wafer having a side at least partially coated with a sticky substance, such as a reticle table cleaner (RTC) adhesive or a polyimide material, when the housing is open. Such a wafer is known as a sticky wafer, and utility stage 500 may load, transfer, and deliver the wafer to a utility device that presses the sticky side of the sticky wafer against one of the wafer tables to collect particulate contaminants from the top of the burls. Thus, tool 650 may be one of these tools.

[0067]

[0079] Tool storage 520 may be supplied with another type of special dummy wafer with a backside having spikes, known as a spiked wafer, when the enclosure is open. Utility stage 500 may load, transport, and transfer this special dummy wafer to a utility device that may press the spiked wafer against one of the wafer tables to increase the surface roughness of the wafer table. Thus, tool 650 may be one of these tools.

[0068]

[0080] The tool store 520 may be supplied with an X-ray charge removal tool when the enclosure is open. The utility stage 500 loads and transports the X-ray charge removal tool and transfers it to a utility device that uses the X-ray charge removal tool to discharge the EUV clamp surface to mitigate cycle-induced charging. Other tools that may be available in the tool store 520 and that the utility stage 500 may transfer and load into the device for use according to aspects of other embodiments include laser cleaners to etch and remove large particle contaminants, cameras to identify the location of lost wafers, in-system bur inspection, wafer alignment, additional alignment sensors, UV ozone cleaners to clean carbon contaminants from fiber carbon contaminants, etc., "sticky stick" particle removers to prevent large particle contaminants from affecting the overlay, and sticky stones for localized inter-bur particle removal. Thus, the tool 650 may be one of these tools.

[0069]

[0081] The utility stage 500 also allows for flipping of wafers within the system so that no surface of the wafer transport system can come into contact with the chuck-side surface of the wafer other than the chuck itself, allowing, for example, for wafers to be flipped only when the wafer is on the chuck to clean only the wafer chuck and reduce cross-contamination from other wafer contact points.

[0070]

[0082] Utility stage 500 may also have access to burn-in tools, such as covers to protect critical hardware such as lenses during flash. Utility stage 500 may have access to long-term maintenance tools, such as particle traps that contain high-voltage electrodes to collect particles and are replaceable in the system, reducing defects. Thus, tool 650 may be one of these tools.

[0071]

[0083] The incorporation of the aforementioned utility stage may also facilitate extending tool life. For example, if only one stone is available and the stone cannot be replaced, then that stone will generally be a cleaning stone adapted to perform a cleaning function. To perform life-extending operations such as planarization, the machine must be taken offline and incur a downtime penalty that operators tend to minimize. However, another potential use of the utility stage may be to perform flatness reconditioning, specifically planarizing the periphery of the chuck to restore flatness using a reconditioning stone better suited to its function (hard enough to wear down burrs) than a cleaning stone. Operators are more likely to use such tools if they are conveniently available. Thus, being able to place a reconditioning stone in the system without incurring a machine downtime penalty (without opening the enclosure) can extend the life of the parts. Similarly, a lens cleaning tool may be one of the tools that the utility stage can load and use, so that the stage can access and clean lenses that become contaminated over time by outgassing photoresist on the wafer, again helping to extend the life of the machine.

[0072]

[0084] According to another aspect of the embodiment, FIG. 7 is a functional block diagram illustrating a control system of a lithographic apparatus including a utility stage. The controller 700 receives signals from a user interface 710 or an overall system controller 720. Through the user interface 710, a user can initiate a procedure in which the utility device is used or the utility stage loads or unloads a tool from the utility device. The overall system controller 720 can also initiate the procedure at a set time, for example, or in response to an indication that such a procedure is required, for example, if excessive hot spots are detected on the wafer. The controller 700 provides control signals to a first wafer table positioner 730, a second wafer table positioner 740, a utility stage positioner 750, a utility device actuator 760, and a tool storage actuator 770. The controller 700 ensures that the wafer table and the utility stage move without interfering with each other. The controller 700 can also provide signals to activate the load and unload functions of the utility stage. Similarly, the controller 700 may provide signals to control the loading and unloading of utility devices and tool stores. Those skilled in the art will appreciate that this division of functionality between components is arbitrary and that other divisions are possible.

[0073]

[0085] The above description includes examples of multiple embodiments. Of course, it is not possible to describe every conceivable combination of components or methodologies to describe the above-described embodiments, but one of ordinary skill in the art will appreciate that many further combinations and permutations of the various embodiments are possible. Accordingly, the described embodiments are intended to embrace all such changes, modifications, and variations that fall within the spirit and scope of the appended claims. Furthermore, to the extent that the term "comprises" is used in the detailed description or claims, this term is intended to be as inclusive as "comprises" as the term "comprises" is interpreted when employed as a transitional term in the claims. Also, although elements of the described aspects and / or embodiments may be described or claimed in the singular, the plural is contemplated unless limitation to the singular is expressly stated. Additionally, all or a portion of any aspect and / or embodiment may be utilized with all or a portion of any other aspect and / or embodiment, unless otherwise stated.

[0074]

[0086] It should be understood that the Detailed Description section, and not the Summary and Abstract sections, are intended to be used to interpret the claims. The Summary and Abstract sections may describe one or more, but not all, exemplary embodiments of the invention contemplated by the inventors, and thus are not intended to limit the scope of the invention and the appended claims in any way.

[0075]

[0087] The present invention has been described above using functional building blocks illustrating the implementation of specific functions and relationships thereof. The boundaries of these functional building blocks have been arbitrarily defined herein for the convenience of description. Alternative boundaries can be defined as long as the specific functions and relationships thereof are appropriately performed.

[0076]

[0088] The embodiments can be further described using the following clauses. 1. A housing; at least one object table disposed within the housing and adapted to move between a plurality of positions within the housing; a utility device disposed within a utility zone within the enclosure; a utility stage disposed within the housing and adapted to move from a parked position to the utility zone, the utility stage adapted to carry at least one tool from the parked position to the utility zone; 1. A photolithography apparatus comprising: 2. A photolithography apparatus as described in clause 1, further comprising a tool storage section disposed within the housing adjacent to the standby position and a plurality of tools stored within the tool storage section, wherein the utility stage is adapted to unload the first tool from the tool storage section, transport the first tool to the utility device, and load the first tool into the utility device. 3. A photolithography apparatus as described in clause 2, wherein the object table includes a wafer table, the utility device includes an object table cleaning tool disposed at the utility position, and the first tool includes a first cleaning stone. 4. The photolithography apparatus of clause 2, wherein the utility stage is further adapted to unload the first tool from the utility device, transport the first tool to the tool storage, and load the first tool to the tool storage. 5. A photolithography apparatus as described in clause 1, wherein the at least one object table includes a first wafer table and a second wafer table. 6. The photolithography apparatus of clause 1, wherein the utility stage includes an extendable robotic arm positioned to position the utility stage. 7. A housing; a first wafer table disposed within the housing and adapted to move between a plurality of coplanar positions within the housing; a second wafer table disposed within the housing and adapted to move between a plurality of coplanar positions within the housing, the second wafer table being moved to avoid interfering with movement of the first wafer table, and the first wafer table being moved to avoid interfering with movement of the second wafer table; a utility device disposed within the utility zone within the enclosure and adapted to perform a utility operation on the wafer; a utility stage disposed within the housing and adapted to move from a parked position to the utility zone, the utility stage adapted to carry at least one tool from the parked position to the utility zone and moved and positioned to avoid interfering with movement of the first wafer table and the second wafer table; 1. A photolithography apparatus comprising: 8. A photolithography apparatus as described in clause 7, further comprising a tool storage section disposed within the housing adjacent to the standby position, and a plurality of tools stored within the tool storage section, and the utility stage adapted to unload the first tool from the tool storage section, transport the first tool to the utility device, and load the first tool into the utility device. 9. The photolithography apparatus of clause 8, wherein the utility device includes a wafer table cleaning tool disposed within the utility zone, the first tool including a first cleaning stone. 10. The photolithography apparatus of clause 8, wherein the plurality of tools stored in the tool storage unit includes a plurality of cleaning stones. 11. A photolithography apparatus as described in clause 8, wherein the first tool includes an adhesive wafer and the utility device includes a wafer table cleaning tool adapted to press the adhesive wafer against a wafer receiving surface of the wafer table. 12. A photolithography apparatus as described in clause 8, wherein the first tool includes a spiked wafer and the utility device includes a wafer table cleaning tool adapted to press the spiked wafer against a wafer receiving surface of the wafer table. 13. The photolithography apparatus of clause 8, wherein the utility stage is further adapted to unload the first tool from the utility device, transport the first tool to the tool storage, and load the first tool to the tool storage. 14. The photolithography apparatus of clause 7, wherein the utility stage includes an extendable robotic arm. 15. A method of operating a photolithography apparatus, the photolithography apparatus including: a housing; a first wafer table disposed within the housing and adapted to move between a plurality of coplanar positions within the housing; a second wafer table disposed within the housing and adapted to move between a plurality of coplanar positions within the housing; a utility device disposed within a utility zone within the housing and adapted to perform a utility operation on the wafer; and a utility stage disposed within the housing and adapted to move from a park position to the utility zone, the utility stage adapted to carry at least one tool from the park position to the utility zone; placing the first wafer table in a first neutral position where the first wafer table does not interfere with movement of the utility stage from the standby position to the utility zone; placing the second wafer table in a second neutral position where the second wafer table does not interfere with movement of the utility stage from the standby position to the utility zone; moving the utility stage from a standby position to a utility zone; A method comprising: 16. The method of claim 15, wherein the utility stage unloads the tool from the tool storage when the utility stage is in the standby position. 17. The method of claim 16, wherein the first tool is one of a plurality of tools stored in a tool storage unit. 18. The method of claim 16, wherein the utility stage loads the tool into the utility device when the utility stage is within the utility zone. 19. The method of claim 18, wherein when the utility stage is in the standby position, the utility stage unloads the tool from the tool storage, moves to the utility zone, and loads the tool into a utility device in the utility zone. 20. Using the utility stage, unloading a first tool from the utility stage in the utility zone; moving the utility stage to a standby position; unloading the first tool from the utility stage and loading the first tool into the tool storage; unloading the second tool from the tool storage and loading the second tool into the utility stage; Moving the utility stage to the utility zone; loading a second tool into the utility device using a utility stage; 17. The method of claim 16, further comprising: 21. The method of claim 16, wherein the utility device includes a wafer table cleaning tool disposed within the utility zone, the first tool including a first cleaning stone. 22. The method of claim 16, wherein the first tool includes a sticky wafer and the utility device includes a wafer table cleaning tool adapted to press the sticky wafer against a wafer receiving surface of the wafer table. 23. The method of claim 16, wherein the first tool includes a spiked wafer and the utility device includes a wafer table cleaning tool adapted to press the spiked wafer against a wafer receiving surface of the wafer table. 24. The method of claim 16, wherein the photolithography apparatus includes a lens, the first tool includes a lens cleaning device, and the utility stage is adapted to move to the lens and to position the lens cleaning device to clean the lens.

Claims

1. A housing and at least one object table disposed within the housing and adapted to move between a plurality of positions within the housing; a utility device disposed within a utility zone within the housing; a utility stage disposed within the housing and adapted to move from a parked position to the utility zone, the utility stage adapted to carry at least one tool from the parked position to the utility zone; 1. A photolithography apparatus comprising:

2. a tool storage section disposed within the housing adjacent the standby position; and a plurality of tools stored within the tool storage section, the utility stage is adapted to unload a first tool from the tool storage, transport the first tool to the utility device, and load the first tool into the utility device; the object table includes a wafer table; the utility device includes an object table cleaning tool disposed at the utility location; the first tool includes a first cleaning stone; 2. The photolithography apparatus of claim 1, wherein the utility stage is further adapted to unload the first tool from the utility device, transport the first tool to the tool storage, and load the first tool to the tool storage.

3. the at least one object table includes a first wafer table and a second wafer table; and / or The photolithographic apparatus of claim 1 , wherein the utility stage includes an extendable robotic arm positioned to position the utility stage.

4. A housing and a first wafer table disposed within the housing and adapted to move between a plurality of coplanar positions within the housing; a second wafer table disposed within the housing and adapted to move between the plurality of coplanar positions within the housing, the second wafer table being moved to avoid interfering with movement of the first wafer table, and the first wafer table being moved to avoid interfering with movement of the second wafer table; a utility device disposed within the enclosure in a utility zone and adapted to perform a utility operation on a wafer; a utility stage disposed within the housing and adapted to move from a parked position to the utility zone, the utility stage adapted to carry at least one tool from the parked position to the utility zone and moved and positioned to avoid interfering with movement of the first wafer table and the second wafer table; 1. A photolithography apparatus comprising:

5. a tool storage section disposed within the housing adjacent to the standby position; and a plurality of tools stored within the tool storage section, 5. The photolithography apparatus of claim 4, wherein the utility stage is adapted to unload a first tool from the tool storage, transport the first tool to the utility device, and load the first tool to the utility device.

6. the utility device includes a wafer table cleaning tool disposed within the utility zone; the first tool includes a first cleaning stone; the plurality of tools stored in the tool storage unit include a plurality of cleaning stones; the first tool includes an adhesive wafer; The photolithography apparatus of claim 5 , wherein the utility device comprises a wafer table cleaning tool adapted to press the sticky wafer against a wafer receiving surface of a wafer table.

7. the first tool includes a spiked wafer; the utility device includes a wafer table cleaning tool adapted to press the spiked wafer against a wafer receiving surface of a wafer table; 6. The photolithography apparatus of claim 5, wherein the utility stage is further adapted to unload the first tool from the utility device, transport the first tool to the tool storage, and load the first tool to the tool storage.

8. The photolithographic apparatus of claim 4 , wherein the utility stage comprises an extendable robotic arm.

9. 1. A method of operating a photolithography apparatus, comprising the steps of: the photolithography apparatus includes a housing, a first wafer table disposed within the housing and adapted to move between a plurality of coplanar positions within the housing, a second wafer table disposed within the housing and adapted to move between a plurality of coplanar positions within the housing, a utility device disposed within a utility zone within the housing and adapted to perform a utility operation on a wafer, and a utility stage disposed within the housing and adapted to move from a park position to the utility zone, the utility stage adapted to carry at least one tool from the park position to the utility zone; The method comprises: placing the first wafer table in a first neutral position in which the first wafer table does not interfere with movement of the utility stage from the park position to the utility zone; placing the second wafer table in a second neutral position in which the second wafer table does not interfere with movement of the utility stage from the park position to the utility zone; moving the utility stage from the standby position to the utility zone; A method comprising:

10. The method of claim 9 , wherein the utility stage unloads a tool from a tool store when the utility stage is in the parked position.

11. the first tool is one of a plurality of tools stored in the tool storage unit; when the utility stage is within the utility zone, the utility stage loads a tool onto a utility device; The method of claim 10 , wherein when the utility stage is in the standby position, the utility stage unloads a tool from a tool store, moves to the utility zone, and loads the tool into a utility device in the utility zone.

12. unloading a first tool from the utility stage in the utility zone using the utility stage; moving the utility stage to the standby position; unloading the first tool from the utility stage and loading the first tool into a tool storage unit; unloading a second tool from the tool storage and loading the second tool into the utility stage; moving the utility stage to the utility zone; loading the second tool into the utility device using the utility stage; The method of claim 10 further comprising:

13. the utility device includes a wafer table cleaning tool disposed within the utility zone; the first tool includes a first cleaning stone; the first tool includes an adhesive wafer; The method of claim 10 , wherein the utility device comprises a wafer table cleaning tool adapted to press the sticky wafer against a wafer receiving surface of a wafer table.

14. the first tool includes a spiked wafer; The method of claim 10 , wherein the utility device comprises a wafer table cleaning tool adapted to press the spiked wafer against a wafer receiving surface of a wafer table.

15. the photolithography apparatus includes a lens; the first tool includes a lens cleaning device; The method of claim 10 , wherein the utility stage is adapted to move to the lens and to position the lens cleaning device to clean the lens.

Images