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`1111111111111111111111111111111111111111111111111111111111111
`US00823 313 7B2
`
`c12) United States Patent
`Modderman
`
`(10) Patent No.:
`(45) Date of Patent:
`
`US 8,233,137 B2
`*Jul. 31, 2012
`
`(54) LITHOGRAPHIC APPARATUS AND DEVICE
`MANUFACTURING METHOD
`
`(75)
`
`Inventor: Theodorus Marinus Modderman,
`Nuenen (NL)
`
`(73) Assignee: ASML Netherlands B.V., Veldhoven
`(NL)
`
`( *) Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 534 days.
`
`This patent is subject to a terminal dis(cid:173)
`claimer.
`
`(21) Appl. No.: 12/327,414
`
`(22) Filed:
`
`Dec. 3, 2008
`
`(65)
`
`Prior Publication Data
`
`US 2009/0079951 Al
`
`Mar. 26, 2009
`
`Related U.S. Application Data
`
`(63) Continuation of application No. 11/015,766, filed on
`Dec. 20, 2004, now Pat. No. 7,528,931.
`
`(51)
`
`Int. Cl.
`G03B 27142
`(2006.01)
`G03B 27152
`(2006.01)
`(52) U.S. Cl. ............................................ 355/53; 355/55
`(58) Field of Classification Search .................... 355/30,
`355/53, 55, 72-76; 356/399-401
`See application file for complete search history.
`
`(56)
`
`References Cited
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`(Continued)
`
`DE
`
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`(Continued)
`
`OTHER PUBLICATIONS
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`3, 2010.
`
`(Continued)
`
`Primary Examiner- Hung Henry Nguyen
`(74) Attorney, Agent, or Firm- Pillsbury Winthrop Shaw
`PittmanLLP
`
`ABSTRACT
`(57)
`In a single or multiple stage lithography apparatus, a table
`provides a confining surface to a liquid supply system during,
`for example, substrate table exchange and/or substrate load(cid:173)
`ing and unloading. In an embodiment, the table has a sensor to
`make a measurement of the projection beam during, for
`example, substrate table exchange and/or substrate loading
`and unloading.
`
`38 Claims, 4 Drawing Sheets
`
`PW
`
`Nikon Exhibit 1001 Page 1
`
`

`

`US 8,233,137 B2
`Page 2
`
`U.S. PATENT DOCUMENTS
`7,528,931 B2 *
`5/2009 Modderman ................... 355/53
`2002/0020821 A1
`212002 Van San ten eta!. .......... 250/492
`2002/0163629 A1
`1112002 Switkes eta!. .................. 355/53
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`7/2004 Lof et a!.
`........................ 378/34
`2004/0160582 A1
`8/2004 Lof eta!. ........................ 355/30
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`8/2004 Lof eta!. ........................ 355/30
`10/2004 Lof eta!. ........................ 355/30
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`2004/0227925 A1 *
`1112004 Sato ................................ 355/72
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`12/2004 Bischoff ....................... 356/635
`2004/0263809 A1
`12/2004 Nakano ........................... 355/30
`2005/0007569 A1
`112005 Streefkerk eta!. .............. 355/30
`2005/0018155 A1
`112005 Cox eta!. ........................ 355/30
`2005/0024609 A1
`2/2005 De Smit et al .................. 355/18
`2005/0030497 A1
`2/2005 Nakamura ...................... 355/30
`3/2005 Streefkerk eta!. .............. 355/30
`2005/0046813 A1
`2005/0046934 A1
`3/2005 Ho eta!. ....................... 359/380
`2005/0052632 A1
`3/2005 Miyajima ....................... 355/53
`2005/0094116 A1
`5/2005 Flagello eta!. ................. 355/53
`2005/0094125 A1
`5/2005 Arai ................................ 355/72
`2005/0122505 A1
`6/2005 Miyajima ....................... 355/72
`2005/0132914 A1
`6/2005 Mulkens eta!.
`1011463.1
`6/2005 Nakamura ...................... 355/53
`2005/0134817 A1
`2005/0140948 A1
`6/2005 Tokita ............................. 355/30
`2005/0146693 A1
`7/2005 Ohsaki ............................ 355/30
`2005/0146694 A1
`7/2005 Tokita ............................. 355/30
`2005/0151942 A1
`7/2005 Kawashima .................... 355/30
`2005/0200815 A1
`9/2005 Akamatsu ....................... 353/53
`2005/0213065 A1
`9/2005 Kitaoka .......................... 355/53
`2005/0213066 A1
`9/2005 Sumiyoshi ...................... 355/53
`2005/0219489 A1
`10/2005 Nei eta!. ........................ 355/53
`2005/0233081 A1
`10/2005 Tokita ........................... 427/256
`2010/0182584 A1
`7/2010 Shibazaki
`
`DE
`DE
`DE
`EP
`EP
`EP
`FR
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`JP
`JP
`JP
`JP
`JP
`JP
`JP
`JP
`JP
`JP
`JP
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`JP
`JP
`JP
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`JP
`JP
`JP
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`JP
`JP
`JP
`JP
`JP
`JP
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`wo
`wo
`
`FOREIGN PATENT DOCUMENTS
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`
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`12/659,894, dated Mar. 24, 2010 (1 page).
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`Lab, Orlando 2001-1, Dec. 17, 2001.
`M. Switkes eta!., "Immersion Lithography at 157 nm", J. Vac. Sci.
`Techno!. B., vol. 19, No.6, Nov./Dec. 2001, pp. 2353-2356.
`M. Switkes et al., "Immersion Lithography: Optics for the 50 nm
`Node", 157 Anvers-1, Sep. 4, 2002.
`B.J. Lin, "Drivers, Prospects and Challenges for Immersion Lithog(cid:173)
`raphy", TSMC, Inc., Sep. 2002.
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`closure Bulletin, vol. 20, No. liB, Apr. 1978, p. 4997.
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`SPIE vol. 922, Optical/Laser Micro lithography ( 1988), pp. 256-269.
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`Defects", Solid State Technology, Aug. 1978, vol. 21 008, pp. 68-72.
`S. Owa eta!., "Immersion Lithography; its potential performance and
`issues", SPIE Microlithography 2003, 5040-186, Feb. 27, 2003.
`S. Owa et al., "Advantage and Feasibility of Immersion Lithogra(cid:173)
`phy", Proc. SPIE 5040 (2003).
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`Solutions", May 15, 2003.
`H. Kawata eta!., "Optical Projection Lithography using Lenses with
`Numerical Apertures Greater than Unity", Microelectronic Engi(cid:173)
`neering 9 (1989), pp. 31-36.
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`Interferometric Lithography", J. Vac. Sci. Techno!. B., vol. 17, No.6,
`Nov./Dec. 1999, pp. 3306-3309.
`B.W. Smith et a!., "Immersion Optical Lithography at 193nm",
`FUTURE FAB International, vol. 15, Jul. 11, 2003.
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`Projection Lithography with an Oil Immersion Lens", Jpn. J. Appl.
`Phys. vol. 31 (1992), pp. 4174-4177.
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`vol. 10, No.6, Nov./Dec. 1992, pp. 3032-3036.
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`Photonics Spectra, Photonics TechnologyWorld, Oct. 2003 Edition,
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`Immersion Lithography", NGL Workshop 2003, Jul. 10, 2003, Slide
`Nos. 1-33.
`
`Nikon Exhibit 1001 Page 2
`
`

`

`US 8,233,137 B2
`Page 3
`
`S. Owa eta!., "Update on 193nm immersion exposure tool", Litho
`Forum, International SEMATECH, Los Angeles, Jan. 27-29, 2004,
`Slide Nos. 1-51.
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`Slide Nos. 1-22.
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`Microlithography 2004, 5377-65, Mar. 2004.
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`on the Imaging Layer", IBM Technical Disclosure Bulletin, vol. 27,
`No. 11, Apr. 1985, p. 6521.
`
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`EE Times, Jan. 5, 2004.
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`resolution, depth of focus, and immersion lithography, J Microlith.,
`Microfab., Microsyst. 1(1):7-12 (2002).
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`26, 2010.
`U.S. Appl. No. 60/462,499, filed Apr. 11,2003, Binnard.
`* cited by examiner
`
`Nikon Exhibit 1001 Page 3
`
`

`

`U.S. Patent
`
`Jul. 31, 2012
`
`Sheet 1 of 4
`
`US 8,233,137 B2
`
`Fig. 1
`
`PM
`
`L
`
`PL
`
`Nikon Exhibit 1001 Page 4
`
`

`

`U.S. Patent
`
`Jul. 31, 2012
`
`Sheet 2 of 4
`
`US 8,233,137 B2
`
`(PRIOR ART)
`
`(PRIOR ART) Fig. 3
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`wr
`
`(PRIOR ART) Fig. 4
`
`OUT
`
`IN~
`\
`
`0
`0
`0
`
`OUT
`
`..
`
`Nikon Exhibit 1001 Page 5
`
`

`

`U.S. Patent
`
`Jul. 31, 2012
`
`Sheet 3 of 4
`
`US 8,233,137 B2
`
`Fig. 5
`
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`
`14
`
`Fig. 6
`
`PW
`
`12
`
`AS
`
`Nikon Exhibit 1001 Page 6
`
`

`

`U.S. Patent
`
`Jul. 31, 2012
`
`Sheet 4 of 4
`
`US 8,233,137 B2
`
`Fig. 7
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`Nikon Exhibit 1001 Page 7
`
`

`

`US 8,233,137 B2
`
`1
`LITHOGRAPHIC APPARATUS AND DEVICE
`MANUFACTURING METHOD
`
`This application is continuation of U.S. patent application
`Ser. No. 11/015,766, entitled "Lithographic Apparatus and
`Device Manufacturing Method", filed on Dec. 20, 2004, now
`U.S. Pat. No. 7,528,931, the content of which is incorporated
`herein in its entirety by reference.
`
`FIELD
`
`The present invention relates to a lithographic apparatus
`and a method for manufacturing a device.
`
`BACKGROUND
`
`A lithographic apparatus is a machine that applies a desired
`pattern onto a substrate, usually onto a target portion of the
`substrate. A lithographic apparatus can be used, for example,
`in the manufacture of integrated circuits (ICs). In that
`instance, a patterning device, which is alternatively referred
`to as a mask or a reticle, may be used to generate a circuit
`pattern to be formed on an individual layer of the IC. This
`pattern can be transferred onto a target portion (e.g. compris(cid:173)
`ing part of, one, or several dies) on a substrate (e.g. a silicon
`wafer). Transfer of the pattern is typically via imaging onto a
`layer of radiation-sensitive material (resist) provided on the
`substrate. In general, a single substrate will contain a network
`of adjacent target portions that are successively patterned.
`Known lithographic apparatus include so-called steppers, in 30
`which each target portion is irradiated by exposing an entire
`pattern onto the target portion at one time, and so-called
`scanners, in which each target portion is irradiated by scan(cid:173)
`ning the pattern through a radiation beam in a given direction
`(the "scanning" -direction) while synchronously scanning the 35
`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.
`It has been proposed to immerse the substrate in the litho(cid:173)
`graphic projection apparatus in a liquid having a relatively 40
`high refractive index, e.g. water, so as to fill a space between
`the final element of the projection system and the substrate.
`The point of this is to enable imaging of smaller features since
`the exposure radiation will have a shorter wavelength in the
`liquid. (The effect of the liquid may also be regarded as 45
`increasing the effective numerical aperture (NA) of the sys(cid:173)
`tem and also increasing the depth offocus.) Other immersion
`liquids have been proposed, including water with solid par(cid:173)
`ticles (e.g. quartz) suspended therein.
`However, submersing the substrate or substrate and sub- 50
`strate table in a bath ofliquid (see, for example, U.S. Pat. No.
`4,509,852, hereby incorporated in its entirety by reference)
`means that there is a large body ofliquid that must be accel(cid:173)
`erated during a scanning exposure. This requires additional or
`more powerful motors and turbulence in the liquid may lead 55
`to undesirable and unpredictable effects.
`One of the solutions proposed is for a liquid supply system
`to provide liquid on only a localized area of the substrate and
`in between the final element of the projection system and the
`substrate using a liquid supply system (the substrate generally 60
`has a larger surface area than the final element of the projec(cid:173)
`tion system). One way which has been proposed to arrange
`for this is disclosed in PCT patent application WO 99/49504,
`hereby incorporated in its entirety by reference. As illustrated
`in FIGS. 2 and3, liquid is supplied by at leastoneinletiN onto 65
`the substrate, preferably along the direction of movement of
`the substrate relative to the final element, and is removed by
`
`2
`at least one outlet OUT after having passed under the projec(cid:173)
`tion system. That is, as the substrate is scanned beneath the
`element in a -X direction, liquid is supplied at the +X side of
`the element and taken up at the -X side. FIG. 2 shows the
`arrangement schematically in which liquid is supplied via
`inlet IN and is taken up on the other side of the element by
`outlet OUT which is connected to a low pressure source. In
`the illustration of FIG. 2 the liquid is supplied along the
`direction of movement of the substrate relative to the final
`10 element, though this does not need to be the case. Various
`orientations and numbers of in- and out-lets positioned
`around the final element are possible, one example is illus(cid:173)
`trated in FIG. 3 in which four sets of an inlet with an outlet on
`either side are provided in a regular pattern around the final
`15 element.
`To maintain the performance of a lithographic apparatus,
`periodic measurements of the performance of the radiation
`source, illumination system and projection system may be
`taken so that corrective measures, such as recalibrations, can
`20 be taken if there is any degradation in the performance of any
`part of the apparatus. One or more sensors may be provided in
`the optical path of the apparatus to measure one or more
`parameters that may affect imaging but it is desired, and in
`some cases essential, to take measurements at substrate level
`25 and directly in the aerial image. Such measurements cannot
`be done concurrently with and at the same as production
`exposure so that periodic downtime is provided, reducing the
`throughput of the apparatus.
`
`SUMMARY
`
`Accordingly, it would be advantageous, for example, to
`provide a lithographic apparatus in which a measurement at
`substrate level may be performed without reduction in
`throughput.
`According to an aspect of the invention, there is provided a
`positioning apparatus for use in a lithographic apparatus for
`projecting a patterned beam of radiation onto a substrate, the
`positioning apparatus comprising:
`a first table connected to a first positioning system config(cid:173)
`ured to displace the first table into and out of a path of the
`patterned beam of radiation, the first table being configured to
`hold a substrate; and
`a second table connected to a second positioning system
`configured to position the second table into the path of the
`patterned beam of radiation when the first table is displaced
`out of the path of the patterned beam of radiation, the second
`table not being configured to hold a substrate.
`According to an aspect of the invention, there is provided a
`lithographic apparatus, comprising:
`a substrate table configured to hold a substrate;
`a projection system configured to project a patterned beam
`of radiation onto the substrate;
`a first positioning system connected to the substrate table
`and configured to displace the substrate table into and out of
`a path of the patterned beam of radiation;
`a sensor table not configured to hold a substrate and com(cid:173)
`prising a sensor configured to sense a property of the pat(cid:173)
`terned beam of radiation; and
`a second positioning system configured to position the
`sensor table into the path of the patterned beam of radiation
`when the first table is displaced out of the path of the patterned
`beam of radiation.
`According to another aspect of the invention, there is pro(cid:173)
`vided a device manufacturing method, comprising:
`projecting a patterned beam of radiation onto a substrate
`held on a table;
`
`Nikon Exhibit 1001 Page 8
`
`

`

`US 8,233,137 B2
`
`3
`displacing the table out of a path of the patterned beam of
`radiation; and
`moving a sensor into the path of the patterned beam of
`radiation and measuring a property of the beam, the moving
`of the sensor and the measuring of the property occurring at
`least partly concurrently with the displacing of the table.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`Embodiments of the invention will now be described, by 10
`way of example only, with reference to the accompanying
`schematic drawings in which corresponding reference sym(cid:173)
`bols indicate corresponding parts, and in which:
`FIG. 1 depicts a lithographic apparatus according to an
`embodiment of the invention;
`FIGS. 2 and 3 depict a liquid supply system for use in a
`lithographic projection apparatus;
`FIG. 4 depicts another liquid supply system for use in a
`lithographic projection apparatus;
`FIG. 5 depicts a liquid supply system for use in a litho(cid:173)
`graphic apparatus according to an embodiment of the inven(cid:173)
`tion;
`FIG. 6 depicts measurement and exposure stations of an
`embodiment of the invention; and
`FIG. 7 is a view similar to FIG. 6 but showing the situation
`during table exchange.
`
`4
`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.
`Generally, the pattern imparted to the radiation beam will
`correspond to a particular functional layer in a device being
`created in the target portion, such as an integrated circuit.
`The patterning device may be transmissive or reflective.
`Examples of patterning devices include masks, program(cid:173)
`mable mirror arrays, and progrmable LCD panels. Masks
`are well known in lithography, and include mask types such as
`binary, alternating phase-shift, and attenuated phase-shift, as
`15 well as various hybrid mask types. An example of a program(cid:173)
`mable 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
`20 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, mag(cid:173)
`netic, electromagnetic and electrostatic optical systems, or
`25 any combination thereof, as appropriate for the exposure
`radiation being used, or for other factors such as the use of an
`immersion liquid or the use of a vacuum. Any use of the term
`"projection lens" herein may be considered as synonymous
`with the more general term "projection system".
`As here depicted, the apparatus is of a transmissive type
`(e.g. employing a transmissive mask). Alternatively, the appa(cid:173)
`ratus may be of a reflective type (e.g. employing a program(cid:173)
`mable mirror array of a type as referred to above, or employ(cid:173)
`ing 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 may be used in parallel, or preparatory steps
`may be carried out on one or more tables while one or more
`40 other tables are being used for exposure.
`Referring to FIG. 1, the illuminator IL receives a radiation
`beam from a radiation source 50. The source and the litho(cid:173)
`graphic apparatus may be separate entities, for example when
`the source is an excimer laser. In such cases, the source is not
`considered to form part of the lithographic apparatus and the
`radiation beam is passed from the source 50 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 50 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. Generally, at least the outer and/or inner radial extent
`(commonly referred to as a-outer and a-inner, respectively)
`of the intensity distribution in a pupil plane of the illuminator
`can be adjusted. In addition, the illuminator IL may comprise
`various other components, such as an integrator IN and a
`condenser CO. The illuminator may be used to condition the
`radiation beam, to have a desired uniformity and intensity
`distribution in its cross-section.
`The radiation beam PB is incident on the patterning device
`65 (e.g., mask MA), which is held on the support structure (e.g.,
`mask table MT), and is patterned by the patterning device.
`Having traversed the patterning device MA, the radiation
`
`DETAILED DESCRIPTION
`
`35
`
`FIG. 1 schematically depicts a lithographic apparatus 30
`according to one embodiment of the invention. The apparatus
`comprises:
`an illumination system (illuminator) IL configured to con(cid:173)
`dition a radiation beam PB (e.g. UV radiation or DUV radia(cid:173)
`tion).
`a support structure (e.g. a mask table) MT constructed to
`support 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 constructed to hold
`a substrate (e.g. a resist-coated wafer) Wand 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 sys(cid:173)
`tem) PL configured to project a pattern imparted to the radia- 45
`tion beam PB 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 opti-
`cal components, such as refractive, reflective, magnetic, elec(cid:173)
`tromagnetic, electrostatic or other types of optical campo- 50
`nents, or any combination thereof, for directing, shaping, or
`controlling radiation.
`The support structure holds the patterning device in a man(cid:173)
`ner that depends on the orientation of the patterning device,
`the design of the lithographic apparatus, and other conditions, 55
`such as for example whether or not the patterning device is
`held in a vacuum environment. The support structure can use
`mechanical, vacuum, electrostatic or other clamping tech(cid:173)
`niques to hold the patterning device. The support structure
`may be a frame or a table, for example, which may be fixed or 60
`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 terms
`"reticle" or "mask" herein may be considered synonymous
`with the more general term "patterning device".
`The term "patterning device" used herein should be
`broadly interpreted as referring to any device that can be used
`
`Nikon Exhibit 1001 Page 9
`
`

`

`US 8,233,137 B2
`
`5
`beam PB passes through the projection system PL, which
`focuses the beam onto a target portion C of the substrate W.
`With the aid of the second positioner PW and position sensor
`IF (e.g. an interferometric device, linear encoder 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 PB. 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 PB, 10
`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), 15
`which form part of the first positioner PM. Similarly, move(cid:173)
`ment of the substrate table WT may be realized using 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 scarmer) the support structure MT may be con- 20
`nected to a short-stroke actuator only, or may be fixed. Pat(cid:173)
`terning 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 as illustrated occupy dedicated target portions, they 25
`may be located in spaces between target portions (these are
`known as scribe-lane alignment marks). Similarly, in situa(cid:173)
`tions in which more than one die is provided on the patterning
`device MA, the patterning device alignment marks may be
`located between the dies.
`The depicted apparatus could be used in at least one of the
`following modes:
`1. In step mode, the support structure MT and the substrate
`table WT are kept essentially stationary, while an entire pat(cid:173)
`tern imparted to the radiation beam is projected onto a target
`portion C at one time (i.e. a single static exposure). The
`substrate table WT is then shifted in the X and/or Y direction
`so that a different target portion C can be exposed. In step
`mode, the maximum size of the exposure field limits the size
`of the target portion C imaged in a single static exposure.
`2. In scan mode, the support structure MT and the substrate
`table WT are scanned synchronously while a pattern imparted
`to the radiation beam is projected onto a target portion C (i.e.
`a single dynamic exposure). The velocity and direction of the
`substrate table WT relative to the support structure MT may 45
`be determined by the (de-)magnification and image reversal
`characteristics of the projection system PL. In scan mode, the
`maximum size of the exposure field limits the width (in the
`non-scarming direction) of the target portion in a single
`dynamic exposure, whereas the lengthofthe scanning motion 50
`determines the height (in the scarming direction) of the target
`portion.
`3. In another mode, the support structure MT is kept essen(cid:173)
`tially stationary holding a programmable patterning device,
`and the substrate table WT is moved or scarmed while a 55
`pattern imparted to the radiation beam is projected onto a
`target portion C. In this mode, generally a pulsed radiation
`source is employed and the programmable patterning device
`is updated as required after each movement of the substrate
`table WT or in between successive radiation pulses during a 60
`scan. This mode of operation can be readily applied to mask(cid:173)
`less 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.
`
`6
`A further immersion lithography solution with a localized
`liquid supply system is shown in FIG. 4. Liquid is supplied by
`two groove inlets IN on either side of the projection system
`PL and is removed by a plurality of discrete outlets OUT
`arranged radially outwardly of the inlets IN. The inlets IN and
`OUT can be arranged in a plate with a hole in its center and
`through which the projection beam is projected. Liquid is
`supplied by one groove inlet IN on one side of the projection
`system PL and removed by a plurality of discrete outlets OUT
`on the other side of the projection system PL, causing a flow
`of a thin film ofliquid between the projection system PL and
`the substrate W. The choice of which combination of inlet IN
`and outlets OUT to use can depend on the direction of move(cid:173)
`ment of the substrate W (the other combination of inlet IN and
`outlets OUT being inactive).
`Another immersion lithography solution with a localized
`liquid supply system solution which has been proposed is to
`provide the liquid supply system with a liquid confinement
`structure which extends along at least a part of a boundary of
`the space between the final element of the projection system
`and the substrate table. The liquid confinement structure is
`substantially stationary relative to the projection system in the
`XY plane though there may be some relative movement in the
`Z direction (in the direction of the optical axis). A seal is
`formed between the liquid confinement structure and the
`surface of the substrate. In an embodiment, the seal is a
`contactless seal such as a gas seal. Such a system with a gas
`seal is disclosed in U.S. patent application Ser. No. 10/705,
`783, hereby incorporated in its entirety by reference.
`FIG. 5 shows a liquid supply system comprising a liquid
`confinement structure (sometimes referred to as an immer(cid:173)
`sion hood or showerhead) according to an embodiment of the
`invention. In particular, FIG. 5 depicts an arrangement of a
`reservoir 10, which forms a contactless seal to the substrate
`35 around the image field of the projection system so that liquid
`is confined to fill a space between the substrate surface and the
`final element of the projection system. A liquid confinement
`structure 12 positioned below and surrounding the final ele(cid:173)
`ment of the projection system PL forms the reservoir. Liquid
`40 is brought into the space below the projection system and
`within the liquid confinement structure 12. The liquid con(cid:173)
`finement structure 12 extends a little above the final element
`of the projection system and the liquid level ris