111111
`
`1111111111111111111111111111111111111111111111111111111111111111111111111111
`US 20040263809Al
`
`(19) United States
`(12) Patent Application Publication
`Nakano
`
`(10) Pub. No.: US 2004/0263809 Al
`Dec. 30, 2004
`( 43) Pub. Date:
`
`(54)
`
`IMMERSION EXPOSURE TECHNIQUE
`
`Publication Classification
`
`(75)
`
`Inventor: Hitoshi Nakano, Tochigi (JP)
`
`Correspondence Address:
`FITZPATRICK CELLA HARPER & SCINTO
`30 ROCKEFELLER PLAZA
`NEW YORK, NY 10112 (US)
`
`(73) Assignee: CANON KABUSHIKI KAISHA,
`Tokyo (JP)
`
`(21) Appl. No.:
`
`10/872,513
`
`(22) Filed:
`
`Jun.22,2004
`
`(30)
`
`Foreign Application Priority Data
`
`Jun. 27, 2003
`
`(JP) ...................................... 2003-185389
`
`(51)
`Int. CI? ..................................................... G03B 27/52
`(52) U.S. Cl. ................................. 355/30; 355/53; 355!72
`
`(57)
`
`ABSTRACT
`
`It is an object of this invention to provide an exposure
`technique which uses immersion method and is highly
`practical. For example, an exposure apparatus includes a
`substrate stage which holds and moves a substrate, and a
`supply unit which has a supply nozzle and supplies a liquid
`to the surface of the substrate. The opening of the supply
`nozzle is arranged at a side of a projection optical system so
`as to oppose the substrate, and the supply unit supplies the
`liquid in accordance with movement of the substrate by the
`substrate stage.
`
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`
`Nikon Exhibit 1014 Page 1
`
`

`

`Patent Application Publication Dec. 30, 2004 Sheet 1 of 17
`
`US 2004/0263809 A1
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`Nikon Exhibit 1014 Page 2
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`

`

`Patent Application Publication Dec. 30, 2004 Sheet 2 of 17
`
`US 2004/0263809 Al
`
`FIG. 2A
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`Nikon Exhibit 1014 Page 3
`
`

`

`Patent Application Publication Dec. 30, 2004 Sheet 3 of 17
`
`US 2004/0263809 Al
`
`FIG. 3
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`Nikon Exhibit 1014 Page 4
`
`

`

`Patent Application Publication Dec. 30, 2004 Sheet 4 of 17
`
`US 2004/0263809 Al
`
`FIG. 4
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`Nikon Exhibit 1014 Page 5
`
`

`

`Patent Application Publication Dec. 30, 2004 Sheet 5 of 17
`
`US 2004/0263809 Al
`
`FIG. 5
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`Nikon Exhibit 1014 Page 6
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`

`

`Patent Application Publication Dec. 30, 2004 Sheet 6 of 17
`
`US 2004/0263809 Al
`
`FIG. 6
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`Nikon Exhibit 1014 Page 7
`
`

`

`Patent Application Publication Dec. 30, 2004 Sheet 7 of 17
`
`US 2004/0263809 Al
`
`FIG. 7
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`Nikon Exhibit 1014 Page 8
`
`

`

`Patent Application Publication Dec. 30, 2004 Sheet 8 of 17
`
`US 2004/0263809 Al
`
`FIG. 8
`
`22
`
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`
`Nikon Exhibit 1014 Page 9
`
`

`

`Patent Application Publication Dec. 30, 2004 Sheet 9 of 17
`
`US 2004/0263809 Al
`
`FIG. 9A
`
`FIG. 98
`
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`
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`
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`Nikon Exhibit 1014 Page 10
`
`

`

`Patent Application Publication Dec. 30, 2004 Sheet 10 of 17
`
`US 2004/0263809 A1
`
`FIG. 10A
`4
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`Nikon Exhibit 1014 Page 11
`
`

`

`Patent Application Publication Dec. 30, 2004 Sheet 11 of 17
`
`US 2004/0263809 Al
`
`FIG. 11A
`
`21
`
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`
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`
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`
`Nikon Exhibit 1014 Page 12
`
`

`

`Patent Application Publication Dec. 30, 2004 Sheet 12 of 17
`
`US 2004/0263809 A1
`
`. FIG. 12A
`
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`
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`
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`
`Nikon Exhibit 1014 Page 13
`
`

`

`Patent Application Publication Dec. 30, 2004 Sheet 13 of 17
`
`US 2004/0263809 A1
`
`•
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`Nikon Exhibit 1014 Page 14
`
`

`

`Patent Application Publication Dec. 30, 2004 Sheet 14 of 17
`
`US 2004/0263809 A1
`
`FIG·. 14
`
`20c
`
`Nikon Exhibit 1014 Page 15
`
`

`

`Patent Application Publication Dec. 30, 2004 Sheet 15 of 17
`
`US 2004/0263809 A1
`
`FIG. 15
`
`5
`
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`
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`
`Nikon Exhibit 1014 Page 16
`
`

`

`Patent Application Publication Dec. 30, 2004 Sheet 16 of 17
`
`US 2004/0263809 A1
`
`F I G. 16
`
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`Nikon Exhibit 1014 Page 17
`
`

`

`Patent Application Publication Dec. 30, 2004 Sheet 17 of 17
`
`US 2004/0263809 A1
`
`FIG. 17
`
`CIRCUIT DESIGN
`
`r- S 1
`
`WAFER
`MANUFACTURE
`
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`
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`
`Nikon Exhibit 1014 Page 18
`
`

`

`US 2004/0263809 Al
`
`Dec. 30, 2004
`
`1
`
`IMMERSION EXPOSURE TECHNIQUE
`
`FIELD OF THE INVENTION
`
`[0001] The present invention relates to an exposure tech(cid:173)
`nique for exposing a substrate coated with a photosensitive
`material to a pattern in manufacturing a device such as a
`semiconductor device, liquid crystal display device, or the
`like and, more particularly, to an exposure technique using
`immersion method.
`
`BACKGROUND OF THE INVENTION
`
`[0002] The manufacturing process of a semiconductor
`device with a submicroscopic pattern such as an LSI, VLSI,
`or the like employs a reduction projection exposure appa(cid:173)
`ratus which reduces and projects a pattern formed on a mask
`and transfers it onto a substrate coated with a photosensitive
`agent. Along with an increase in integration degree of
`semiconductor devices, finer patterns have been demanded.
`Concurrently with development of resist processes, mea(cid:173)
`sures have been taken against exposure apparatuses for
`miniaturizing patterns.
`
`[0003] To improve the resolution of an exposure appara(cid:173)
`tus, a method of shortening the exposure wavelength or a
`method of increasing the numerical aperture (NA) of the
`projecting optical system is generally employed.
`
`[0004] As for the exposure wavelength, a KrF excimer
`laser with an oscillation wavelength of 365-nm i-line to
`recently around 248 nm, and an ArF excimer laser with an
`oscillation wavelength around 193 nm have been developed.
`A fluorine (F2) excimer laser with an oscillation wavelength
`around 157 nm is also under development.
`
`[0005] As another technique for increasing the resolution,
`a projection exposure method using immersion is receiving
`attention. Conventionally, the space between the final sur(cid:173)
`face of a projection optical system and a substrate (e.g., a
`wafer) to be exposed is filled with a gas. Immersion per(cid:173)
`forms projection exposure by filling this space with a liquid.
`For example, assume that pure water (whose refractive index
`is 1.33) is to be provided to the space between a projection
`optical system and a wafer, and the maximum incident angle
`of light beams which form an image on the wafer in
`immersion is equal to that in a conventional method. In this
`case, the resolution in immersion becomes 1.33 times higher
`than that in the conventional method even when a light
`source having the same wavelength is used in each method.
`This is equivalent to an increase in NA of the projection
`optical system in the conventional method by a factor of
`1.33. Immersion makes it possible to obtain a resolution
`whose NA is 1 or more, which cannot be attained by the
`conventional method.
`
`[0006] To fill the space between the final surface of a
`projection optical system and a wafer surface, mainly two
`types of methods have been proposed.
`
`[0007] One of them is a method of placing the final surface
`of the projection optical system and the entire wafer in a
`liquid tank. Japanese Patent Laid-Open No. 6-124873 dis(cid:173)
`closes an exposure apparatus using this method.
`
`[0008] The other is a method of supplying a liquid only to
`the space between the projection optical system and the
`
`wafer surface, i.e., a local fill method. W099/49504 dis(cid:173)
`closes an exposure apparatus using this method.
`
`[0009]
`In the method disclosed in Japanese Patent Laid(cid:173)
`Open No. 6-124873, a liquid may splash about when a wafer
`moves at high velocity, and equipment is required to recover
`such splashes. Also, micro-bubbles caused by the wavy
`liquid surface may adversely affect the imaging perfor(cid:173)
`mance. In addition, this method may increase the complexity
`and size of the apparatus.
`
`[0010]
`In the method disclosed in W099/49504, assume
`that the gap between a wafer and a projection optical system
`is small. In this case, even when a nozzle is directed toward
`the gap, and a liquid is supplied to the gap, the liquid
`discharged from the nozzle does not flow into the gap, and
`a gas remains in the gap. For this reason, satisfactory
`immersion cannot be performed. A liquid having failed to
`flow into the gap collides with the perimeter of a projection
`lens and escapes externally. Equipment for recovering the
`liquid needs to be provided around the perimeter, and the
`size of the exposure apparatus increases. Even if a liquid can
`be supplied into the small gap, since the flow resistance
`inside the gap is larger than that outside the gap, the flow
`velocity of the liquid discharged from the nozzle is much
`higher than that in the gap. For this reason, the flow velocity
`changes excessively at the tip of the nozzle or at a portion
`where the liquid collides with the perimeter of the projection
`lens, the flow is greatly disturbed, and air bubbles may be
`generated. These air bubbles may enter the gap between the
`projection lens and the wafer, may prevent transmission of
`light, and may adversely affect the imaging performance of
`the exposure apparatus.
`
`[0011]
`In the method disclosed in W099/49504, a liquid
`supplied onto the wafer needs to be recovered at least every
`wafer replacement, and the productivity of the apparatus
`must be sacrificed to recover the liquid. Recovery of a liquid
`on the wafer means recovering a liquid below the projection
`lens. For this reason, a part of the lower surface of the
`projection lens can get wet every wafer replacement, another
`part can be coated with a thin liquid film, and still another
`part can directly be exposed to the outer air. The environ(cid:173)
`ment surrounding the projection lens and wafer contains
`impurities in larger amounts in comparison with the supplied
`liquid, and a liquid staying on the lower surface of the
`projection lens may absorb an impurity contained in the
`outer air. The liquid staying on the lower surface of the
`projection lens evaporates to the outer air, and the impurity
`originally contained in the liquid or an impurity absorbed
`from the outer air condenses in the liquid. As a result, an
`impurity may be attached to the surface of the projection
`lens to cause clouds or the impurity may remain as a residue
`after the evaporation/drying of the liquid on the surface of
`the projection lens to cause clouds.
`
`SUMMARY OF THE INVENTION
`[0012] The present invention has been made in consider(cid:173)
`ation of the above-mentioned problems, and has as its object
`to increase the practicality of an exposure technique using
`immersion method and, for example, more reliably fill the
`gap between the final surface of a projection optical system
`and a substrate with a liquid, suppress contamination on the
`final surface of the projection optical system, simplify the
`structure of an exposure apparatus, reduce the size of the
`exposure apparatus, or the like.
`
`Nikon Exhibit 1014 Page 19
`
`

`

`US 2004/0263809 Al
`
`Dec. 30, 2004
`
`2
`
`[0013] According to the first aspect of the present inven(cid:173)
`tion, there is provided an exposure apparatus which exposes
`a substrate to a pattern through a projection optical system,
`the apparatus comprising a substrate stage which holds and
`moves the substrate and a supply unit which has a supply
`nozzle and supplies a liquid to a surface of the substrate, an
`opening of the supply nozzle being arranged at a side of the
`projection optical system so as to oppose the substrate, and
`the supply unit supplying the liquid in accordance with
`movement of the substrate by the substrate stage.
`[0014] According to the second aspect of the present
`invention, there is provided an exposure apparatus which
`exposes a substrate to a pattern through a projection optical
`system, the apparatus comprising a substrate stage which
`holds and moves the substrate, a movable fiat plate, a supply
`unit which supplies a liquid to at least one of a portion
`between a final surface of the projection optical system and
`the substrate and a portion between the final surface and the
`fiat plate, and a recovery unit which recovers the liquid from
`at least one of a portion between the final surface and the
`substrate and a portion between the final surface and the fiat
`plate.
`[0015] According to the third aspect of the present inven(cid:173)
`tion, there is provided an exposure apparatus which exposes
`a substrate to a pattern through a projection optical system,
`the apparatus comprising a substrate stage which holds and
`moves the substrate, an opposing member which extends
`from an end portion of a final surface of the projection
`optical system and has a surface opposing the substrate, and
`a supply unit which supplies a liquid to a surface of the
`substrate through an outlet port formed in the opposing
`surface.
`[0016] According to the fourth aspect of the present inven(cid:173)
`tion, there is provided an exposure apparatus which exposes
`a substrate to a pattern through a projection optical system,
`the apparatus comprising a substrate stage which holds and
`moves the substrate, a supply unit which supplies a liquid to
`a space between a final surface of the projection optical
`system and the substrate through a supply port, and a
`ejecting portion which ejects a gas toward the substrate
`through an ejecting port formed outside the supply port with
`respect to the final surface.
`[0017] According to the fifth aspect of the present inven(cid:173)
`tion, there is provided an exposure method of exposing a
`substrate to a pattern through a projection optical system, the
`method comprising steps of moving the substrate by a
`substrate stage, and supplying a liquid to a surface of the
`substrate through a supply nozzle, an opening of the supply
`nozzle being arranged at a side of the projection optical
`system so as to oppose the substrate, and in the supply step,
`the liquid being supplied in accordance with movement of
`the substrate by a substrate stage.
`[0018] According to the sixth aspect of the present inven(cid:173)
`tion, there is provided an exposure method of exposing a
`substrate to a pattern through a projection optical system, the
`method comprising steps of moving the substrate by a
`substrate stage, moving a movable fiat plate, supplying a
`liquid to at least one of a portion between a final surface of
`the projection optical system and the substrate and a portion
`between the final surface and the fiat plate, and recovering
`the liquid from at least one of a portion between the final
`surface and the substrate and a portion between the final
`surface and the fiat plate.
`
`[0019] According to the seventh aspect of the present
`invention, there is provided a device manufacturing method
`comprising a step of exposing a substrate to a pattern using
`any one of the above exposure apparatuses of the present
`invention.
`
`[0020] Other features and advantages of the present inven(cid:173)
`tion will be apparent from the following description taken in
`conjunction with the accompanying drawings, in which like
`reference characters designate the same or similar parts
`throughout the figures thereof.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`[0021] The accompanying drawings, which are incorpo(cid:173)
`rated in and constitute a part of the specification, illustrate
`invention and, together with the
`embodiments of the
`description, serve to explain the principles of the invention.
`
`[0022] FIG. 1 is a view schematically showing the
`arrangement of a preferred embodiment of the present
`invention;
`
`[0023] FIGS. 2A to 2G are sectional views schematically
`showing steps of filling with a liquid the gap between a
`projection optical system and a wafer;
`
`[0024] FIG. 3 is a view showing the first arrangement
`example of a liquid supply nozzle and liquid recovery nozzle
`in an exposure apparatus according to the preferred embodi(cid:173)
`ment of the present invention;
`
`[0025] FIG. 4 is a view showing the second arrangement
`example of the liquid supply nozzle and liquid recovery
`nozzle in the exposure apparatus according to the preferred
`embodiment of the present invention;
`
`[0026] FIG. 5 is a view showing the third arrangement
`example of the liquid supply nozzle and liquid recovery
`nozzle in the exposure apparatus according to the preferred
`embodiment of the present invention;
`
`[0027] FIG. 6 is a view showing the fourth arrangement
`example of the liquid supply nozzle and liquid recovery
`nozzle in the exposure apparatus according to the preferred
`embodiment of the present invention;
`
`[0028] FIG. 7 is a view showing the fifth arrangement
`example of the liquid supply nozzle and liquid recovery
`nozzle in the exposure apparatus according to the preferred
`embodiment of the present invention;
`
`[0029] FIG. 8 is a view schematically showing part of the
`arrangement of another preferred embodiment of the present
`invention;
`
`[0030] FIGS. 9A to 9D are sectional views showing steps
`of feeding a fiat plate below a projection optical system in
`an exposure apparatus according to the embodiment shown
`in FIG. 8;
`
`[0031] FIGS. lOA to lOD are sectional views showing
`another step of feeding the fiat plate below the projection
`system in the exposure apparatus according to the embodi(cid:173)
`ment shown in FIG. 8;
`
`[0032] FIGS. llA to llD are sectional views showing a
`step of generating a liquid film below the projection optical
`system in the exposure apparatus according to the embodi(cid:173)
`ment shown in FIG. 8;
`
`Nikon Exhibit 1014 Page 20
`
`

`

`US 2004/0263809 Al
`
`Dec. 30, 2004
`
`3
`
`[0033] FIGS. 12A to 12C are sectional views showing
`another step of generating a liquid film below the projection
`optical system in the exposure apparatus according to the
`embodiment shown in FIG. 8;
`
`[0034] FIG. 13 is a view showing the sixth arrangement
`example of the liquid supply nozzle and liquid recovery
`nozzle in the exposure apparatus according to the embodi(cid:173)
`ment shown in FIG. 8;
`
`[0035] FIG. 14 is a view showing the seventh arrange(cid:173)
`ment example of the liquid supply nozzle and liquid recov(cid:173)
`ery nozzle in the exposure apparatus according to the
`embodiment shown in FIG. 8;
`
`[0036] FIG. 15 is a view showing an arrangement
`example of a nozzle unit (nozzle unit comprising a plurality
`of nozzles) in the exposure apparatus according to the
`embodiment shown in FIG. 8;
`
`[0037] FIG. 16 is a view showing an application of the
`nozzle unit shown in FIG. 15; and
`
`[ 0038] FIG. 17 is a flowchart showing the whole manu(cid:173)
`facturing process of a semiconductor device.
`
`DETAILED DESCRIPTION OF 1HE
`PREFERRED EMBODIMENTS
`
`[0039] An exposure apparatus according to the present
`invention is useful to, e.g., all exposure methods and expo(cid:173)
`sure apparatuses that use ultraviolet light as exposure light
`and uses immersion in which the gap between a projection
`optical system and a substrate (e.g., a wafer) is filled with a
`liquid. These exposure apparatuses can include, e.g., one
`which projects and transfers a pattern on a master onto a
`substrate while the substrate is in a stationary state and one
`which performs scanning exposure for a substrate to a
`pattern on a master using slit light while synchronously
`scanning the substrate and master.
`
`[0040] A preferred embodiment of the present invention
`will be illustrated below. FIG. 1 is a view schematically
`showing the arrangement of the preferred embodiment of the
`present invention. In FIG. 1, light emitted from an exposure
`light source (not shown) such as an ArF excimer laser or F2
`laser is supplied to an illumination optical system 2. The
`illumination optical system 2 uses the light supplied from
`the exposure light source to illuminate part of a reticle
`(master) 1 with slit light (light having a sectional shape as if
`it passed through a slit). While illuminating the reticle 1 with
`the slit light, a reticle stage (master stage) 3 holding the
`wafer stage 10 and a wafer stage (substrate stage) 10 holding
`a wafer (substrate) 9 perform scanning movement in syn(cid:173)
`chronism with each other. Through this synchronous scan(cid:173)
`ning, an image of the entire pattern on the reticle 1 is
`continuously formed on the wafer 9 through a projection
`optical system 4 to expose to light a resist applied to the
`surface of the wafer 9.
`
`[0041] The two-dimensional positions of the reticle stage
`3 and wafer stage 10 are measured in real time by a reference
`mirror 11 and distance measurement laser interferometer 12,
`respectively. A stage control apparatus 13 performs align(cid:173)
`ment and synchronous control for the reticle 1 (reticle stage
`3) and wafer 9 (wafer stage 10) on the basis of measurement
`values from the reference mirror 11 and distance measure(cid:173)
`ment laser interferometer 12. The wafer stage 10 incorpo-
`
`rates a driving unit which adjusts, changes, or controls the
`vertical position, rotational direction, and tilt of the wafer 9.
`In exposure, the driving unit controls the wafer stage 10 such
`that an exposure region on the wafer 9 precisely coincides
`with the focal plane of the projection optical system 4. The
`position (vertical position and tilt) of the upper surface of the
`wafer 9 is measured by an optical focus sensor (not shown)
`and is supplied to the stage control apparatus 13.
`
`[0042] An exposure apparatus main body is placed in an
`environment chamber (not shown), and the environment of
`the exposure apparatus main body is kept at a predetermined
`temperature. Temperature-controlled air for air conditioning
`is separately supplied to a space surrounding the reticle stage
`3, wafer stage 10, and distance measurement laser interfer(cid:173)
`ometer 12 and a space surrounding the projection optical
`system 4, thereby maintaining the ambient temperature at
`higher precision.
`
`In this embodiment, immersion in which the space
`[0043]
`or gap between the projection optical system 4 and the wafer
`9 is filled with a liquid is implemented by a liquid supply
`nozzle 5 arranged above the wafer 9 and in the vicinity of the
`projection optical system 4 and a liquid recovery nozzle 6
`opposing the liquid supply nozzle 5 through the projection
`optical system 4.
`
`Immersion to be performed in this embodiment
`[0044]
`will be described below in detail. The liquid supply nozzle
`is arranged upstream in a direction in which the wafer 9 is
`scanned during exposure and in the vicinity of the projection
`optical system 4. For example, if the wafer is to be moved
`from right to left, i.e., leftward (second direction), the
`upstream of the scanning direction is on the right (first
`direction). More specifically, if the scanning direction (sec(cid:173)
`ond direction) is indicated by an arrow, the side of the
`starting point of the arrow (first direction) is the upstream.
`The liquid recovery nozzle 6 opposes the liquid supply
`nozzle 5 (i.e., downstream in the scanning direction) through
`the projection optical system 4.
`
`[0045] The liquid supply nozzle 5 is connected to a liquid
`supply unit 7 through a supply pipe 16. Similarly, the liquid
`recovery nozzle 6 is connected to a liquid recovery unit 8
`through a recovery pipe 17. The liquid supply unit 7 can
`include a tank which stores a liquid, a pressure feed unit
`which feeds the liquid, and a flow controller which controls
`the supply flow rate of the liquid. The liquid supply unit 7
`preferably further includes a temperature controller for
`controlling the supply temperature of the liquid. The liquid
`recovery unit 8 can include, e.g., a tank which temporarily
`stores a recovered liquid, a suction unit which sucks the
`liquid, and a flow controller for controlling the recovery flow
`rate of the liquid. An immersion controller 18 receives
`information such as the current position, velocity, accelera(cid:173)
`tion, target position, and moving direction of the wafer stage
`10 from the stage control apparatus 13 and gives instructions
`to start or stop immersion, control the flow rate, and the like
`to the liquid supply unit 7 and liquid recovery unit 8 on the
`basis of this information.
`
`[0046] As an immersion liquid, one which absorbs little
`exposure light is selected. The immersion liquid desirably
`has a refractive index almost equal to that of a dioptric
`element made of, e.g., quartz or fluorite. More specifically,
`examples of the immersion liquid include pure water, func(cid:173)
`tional water, a fluorinated solution (e.g., fluorocarbon), and
`
`Nikon Exhibit 1014 Page 21
`
`

`

`US 2004/0263809 Al
`
`Dec. 30, 2004
`
`4
`
`the like. A dissolved gas is preferably well removed from the
`immersion liquid using a de gasifier. This aims at suppressing
`generation of air bubbles and immediately absorbing any
`generated air bubbles in the liquid. For example, if nitrogen
`and oxygen, which are contained in large quantity in the
`environmental gas, are removed from the liquid by 80% or
`more of the maximum permissible gas content of the liquid,
`generation of air bubbles can sufficiently be suppressed. The
`exposure apparatus may be provided with a degasifier (not
`shown) and may supply a liquid to the liquid supply unit 7
`while removing a gas dissolved in the liquid. As the degas(cid:173)
`ifier, e.g., a vacuum degasifier is preferably used. This
`vacuum degasifier supplies a liquid to one side of a gas(cid:173)
`permeable film, evacuates the other side to a vacuum, and
`traps a gas dissolved in the liquid into the vacuum through
`the film.
`
`[0047] A step of filling a liquid between the projection
`optical system 4 and the wafer 9 will be described with
`reference to FIGS. 2A to 2G.
`
`[0048] While the wafer 9 is in a stationary state or is
`moving, the liquid supply nozzle 5 supplies a liquid f onto
`the wafer 9 at, e.g., a constant flow rate to bring the liquid
`into intimate contact with the lower surface of the liquid
`supply nozzle 5 and the upper surface of the wafer 9. With
`this operation, a satisfactory liquid film is formed (FIG. 2A).
`
`[0049] The wafer 9 starts moving or further moves while
`continuously supplying the liquid from the liquid supply
`nozzle 5. The movement of the wafer is used to guide the
`liquid film below the projection optical system 4 without
`breaking the liquid film (formed in FIG. 2A) (FIGS. 2B and
`2C).
`
`[0050] When the wafer 9 further moves to reach an
`exposure start position, scanning exposure using slit light
`starts (FIG. 2D). During the slit exposure, the liquid supply
`nozzle 5 continuously supplies the liquid, as described with
`reference to FIG. 2C, and the liquid recovery nozzle 6 starts
`recovering the liquid flowing from the downstream side (on
`the left in FIGS. 2A to 2G) of a scanning direction S with
`respect to the projection optical system 4. With this opera(cid:173)
`tion, a space between the wafer 9 and the projection optical
`system 4 is stably filled with the liquid (FIG. 2D).
`
`[0051] When the wafer 9 further moves to reach an
`exposure end position, the exposure using the slit light ends
`(FIG. 2E). Upon completion of the exposure using the slit
`light, the liquid supply nozzle 5 stops supplying the liquid
`(FIG. 2E). The liquid recovery nozzle 6 recovers the liquid
`left on the wafer 9 while moving the wafer 9 in the scanning
`direction S (FIGS. 2F an 2G).
`
`If the liquid is continuously supplied onto the
`[0052]
`surface of the wafer 9 while moving the wafer 9 such that a
`liquid film expands along with the movement of the wafer 9,
`as described above, the gap between the final surface of the
`projection optical system 4 and the wafer can be filled with
`a continuous liquid film. This method can more reliably
`form a liquid film in the gap between the projection optical
`system 4 and the wafer 9 even when the gap is small and can
`more greatly reduce air bubbles in the liquid film, than a
`method disclosed in W099/49504 of directing a nozzle
`toward the gap between the projection optical system 4 and
`the wafer 9 and supplying a liquid toward the gap. Also,
`according to this method, the liquid film moves at a lower
`
`velocity than the wafer and thus can reliably be recovered
`through the liquid recovery nozzle 6. Thus, outward splashes
`of the liquid can effectively be prevented.
`
`[0053] A sequence for supplying and recovering a liquid
`as described above may be performed for each exposure shot
`region (each transfer of a reticle image). Alternatively, the
`sequence may be performed for all or some of the exposure
`shot regions on the wafer. In the latter case, supply and
`recovery of a liquid may be or may not be performed during
`stepping of the wafer between the exposure shot regions.
`
`[0054] The above-mentioned immersion can be applied to
`an exposure apparatus which exposes a wafer while the
`wafer is in a stationary state (e.g., a so-called stepper). In this
`case, when, e.g., the wafer is stepped between exposure shot
`regions, supply and recovery of a liquid is preferably con(cid:173)
`trolled so as to expand a liquid film between an exposure
`shot region to be exposed next and the lower surface of the
`projection optical system 4.
`
`[0055] Preferred examples of the detailed structures and
`layout of the liquid supply nozzle 5 and liquid recovery
`nozzle 6 will be described with reference to FIGS. 3 to 7.
`
`[0056] FIG. 3 is a plan view as seen from above, obtained
`by cutting the exposure apparatus in FIG. 1 above the wafer
`9. The liquid supply nozzle 5 is arranged upstream (in the
`-X direction as seen from the projection optical system 4),
`in a moving directionS (in the +X direction as seen from the
`projection optical system 4) of the wafer 9, of a final surface
`4s of the projection optical system 4 while the liquid
`recovery nozzle 6 is arranged downstream (in the +X
`direction as seen from the projection optical system 4).
`When the exposure apparatus is a scanner (scanning expo(cid:173)
`sure apparatus), the moving direction of the wafer 9 is
`desirably the same as the scanning direction of the wafer in
`exposure in order to stably form a liquid film.
`
`[0057] The liquid supply nozzle 5 is preferably arranged
`such that its lower surface (lower end) is flush with or higher
`than the final surface (lower surface) 4s of the projection
`optical system 4. With this arrangement, a liquid can move
`together with the wafer in intimate contact with the final
`surface of the projection optical system 4 while eliminating
`an air layer. This prevents inclusion of air bubbles in a liquid
`film.
`
`[0058] The liquid recovery nozzle 6 is preferably arranged
`such that its lower surface (lower end) is flush with or higher
`than the final surface (lower surface) 4s of the projection
`optical system 4. With this arrangement, a liquid on the
`wafer can efficiently be recovered while preventing a failure
`to recover the liquid (incomplete recovery).
`
`[0059] A total length L1 of an outlet port through which
`the liquid supply nozzle 5 discharges a liquid is preferably
`equal to or larger than a length Le of a region through which
`exposure light beams pass and is more preferably equal to or
`larger than the width of the final surface 4s of the projection
`optical system 4. A length L2 of the liquid recovery nozzle
`6 is preferably equal to or larger than the length L1 of the
`liquid discharge port of the liquid supply nozzle 5 and is
`more preferably equal to or larger than the width of the fin