NL1036433A1 - Lithographic apparatus, method and device manufacturing method. - Google Patents

Description

LITHOGRAPHIC APPARATUS, METHOD AND DEVICE MANUFACTURING

METHOD

FIELD

[0001J The present invention relates to a lithographic apparatus, a method for reducing gas borne noise in a lithographic apparatus, and a method for manufacturing a device.

BACKGROUND

[0002] A lithographic apparatus is a machine that applies a desired pattern onto a substrate, usually onto a target portion of the substrate. A lithographic apparatus can be used, for example, in the manufacture of integrated circuits (ICs). In such a case, a patterning device, which is alternatively referred to as a mask or a reticle, may be used to generate a circuit pattern to be formed on an individual layer of the IC. This pattern can be transferred onto a target portion (e.g. including part of, one, or several dies) on a substrate (e.g. a silicon wafer). Transfer of the pattern is typically via imaging onto a layer of radiation-sensitive material (resist) provided on the substrate. In general, a single substrate will contain a network of adjacent target portions that are successively patterned. Conventional lithographic apparatus include so-called steppers, in which each target portion is irradiated by exposing an entire pattern onto the target portion at once, and so-called scanners, in which each target portion is irradiated by scanning the pattern through a radiation beam in a given direction (the "scanning"-direction) while synchronously scanning the substrate parallel or anti-parallel to this direction. It is also possible to transfer the pattern from the patterning device to the substrate by imprinting the pattern onto the substrate.

[0003] In the lithographic process of a lithographic apparatus it is desirable that at least the patterning device, the projection system and the substrate stage be properly aligned with respect to each other so that the pattern which is provided by the patterning device in the radiation beam, is properly projected on a target portion of the substrate without, for example, overlay errors, imaging errors or focus errors. In particular, in scanners in which the patterning device support (reticle stage) and the substrate table (substrate stage) are movable to position a particular part of the pattern with respect to a particular part of the substrate, high accuracy positioning is desired. For these movements, positioning systems are provided which control the position of the patterning device support and substrate table with high accuracy. 10 36 4 33 [0004] With continuously increasing demands on the accuracy of imaging, for instance overlay and focus on the one hand and throughput on the other, proper alignment of patterning device support, projection system and substrate table is desirable. For increasing the throughput of the lithographic apparatus, it is desirable to increase the speed and acceleration with which the patterning device support and substrate table are moved and aligned with respect to each other and the projection system.

[0005] However, moving the patterning device support or the substrate table may result in gas flows and pressure waves which may propagate through the space in which these stages but also the projection system are present. Also, the actuation forces of the patterning device support and substrate table may cause vibrations of parts of the stage resulting in gas flows and/or pressure waves, such as acoustic signals or gas flows through the working space. These gas flows and/or pressure waves may excite the projection system, or at least parts of the projection system such as the lenses, or the frame on which the projection system is mounted. The gas flows and/or pressure waves may also excite other parts of the lithographic apparatus being relevant for the alignment of the patterning device support, projection system and substrate table such as sensor or sensor target object of a stage position measurement system. The excitation of the projection system, or the other parts, may cause imaging errors such as errors in overlay, fading and/or focus.

[0006] Generally, it has been found that there are three sources for excitation of the projection system by movements of the patterning device support. One source type is gas borne noise, i.e. noise borne by the gas present between the patterning device support and the projection system, for instance air. This gas borne noise is typically the result of the acceleration of the patterning device support, whereby the gas column before the patterning device support in the direction of movement is pressed away by the moving patterning device support, while gas is sucked in the space created by the moving patterning device support. This gas borne noise may typically be low frequency noise, for instance lower than 150 Hz and may result in overlay errors.

[0007] Another source type is structure borne noise. The movement of the patterning device support, and the forces desired for that movement may result in excitation of a number of parts of the patterning device support or the support structure of the patterning device support. This excitation may be transferred to the projection system via the structural transmission path or via the acoustics transmission path of the lithographic apparatus, for instance a frame or combination of frames which supports both the patterning device support and the projection system. This structure borne noise may typically be of a higher frequency range, for instance above 150 Hz and may have a negative effect on overlay and/or fading.

[0008] Furthermore, the excitation of the parts of the patterning device support or the support structure of the patterning device support may also result in vibrations of these parts. These vibrating parts may also cause pressure waves that excite the projection system or other elements. This results in relative high frequency vibrations of the projection system or other elements, causing a negative effect on overlay and/or fading.

[0009] A third source type is vortex shedding or turbulences, caused by sharp edged of the moveable object. This may generate noise typically of a higher frequency range, for instance above 500 Hz.

SUMMARY

[0010] It is desirable to provide a lithographic apparatus in which the excitation of an element sensitive for disturbances due to gas borne noise as a result of movements of a movable object is substantially reduced. In particular, it is desirable to provide a lithographic apparatus in which the excitation of the projection system due to gas borne noise as a result of movements of the patterning device support is substantially reduced.

[0011] According to an embodiment of the invention, there is provided a lithographic apparatus including an illumination system configured to condition a radiation beam; a support constructed to support a patterning device, the patterning device being capable of imparting the radiation beam with a pattern in its cross-section to form a patterned radiation beam; a substrate table constructed to hold a substrate; a projection system configured to project the patterned radiation beam onto a target portion of the substrate, and passive noise dampener configured to dampen or prevent gas borne noise caused by movement of a movable part of the lithographic apparatus.

[0012] According to an embodiment of the invention, there is provided a method for reducing gas borne noise in a lithographic apparatus, by providing passive noise dampener configured to dampen or prevent gas borne noise caused by movement of a movable part of the lithographic apparatus.

[0013] According to an embodiment of the invention, there is provided a device manufacturing method including coating a substrate with a radiation-sensitive material, projecting a patterned beam of radiation onto the substrate using a lithographic apparatus including an illumination system configured to condition a radiation beam, a support constructed to support a patterning device, the patterning device being capable of imparting the radiation beam with a pattern in its cross-section to form a patterned radiation beam, a substrate table constructed to hold a substrate, a projection system configured to project the patterned radiation beam onto a target portion of the substrate, and a passive noise dampener configured to dampen gas borne noise caused by movement of a movable part of the lithographic apparatus, developing the substrate, and baking the substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts, and in which: [0015] Figure 1 depicts a lithographic apparatus according to an embodiment of the invention; [0016] Figure 2 depicts a part of the lithographic apparatus of Figure 1 in accordance with an embodiment of the invention; [0017] Figure 3 depicts a cross section of an example of a (resonant) panel absorber in accordance with an embodiment of the invention; [0018] Figure 4 depicts a passive noise dampener according to an embodiment of the invention; [0019] Figure 5 depicts a passive noise dampener according to an embodiment of the invention; and [0020] Figures 6a and 6b depict a passive noise dampener according to an embodiment of the invention;

DETAILED DESCRIPTION

[0021] Figure 1 schematically depicts a lithographic apparatus according to one embodiment of the invention. The apparatus includes an illumination system (illuminator) IL configured to condition a radiation beam B (e.g. UV radiation or any other suitable radiation), a patterning device support (e.g. a mask table) MT constructed to support a patterning device (e.g. a mask) MA and connected to a first positioning device PM configured to accurately position the patterning device in accordance with certain parameters. The apparatus also includes a substrate table (e.g. a wafer table) WT or "substrate support" constructed to hold a substrate (e.g. a resist-coated wafer) W and connected to a second positioning device PW configured to accurately position the substrate in accordance with certain parameters. The apparatus further includes a projection system (e.g. a refractive projection lens system) PS configured to project a pattern imparted to the radiation beam B by patterning device MA onto a target portion C (e.g. including one or more dies) of the substrate W.

[0022] The illumination system may include various types of optical components, such as refractive, reflective, magnetic, electromagnetic, electrostatic or other types of optical components, or any combination thereof, for directing, shaping, or controlling radiation.

[0023] The patterning device support holds the patterning device in a manner that depends on the orientation of the patterning device, the design of the lithographic apparatus, and other conditions, such as for example whether or not the patterning device is held in a vacuum environment. The patterning device support can use mechanical, vacuum, electrostatic or other clamping techniques to hold the patterning device. The patterning device support may be a frame or a table, for example, which may be fixed or movable as required. The patterning device support 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." [0024] The term "patterning device" used herein should be broadly interpreted as referring to any device that can be used to impart a radiation beam with a pattern in its cross-section so as to create a pattern in a target portion of the substrate. It should be noted that the pattern imparted to the radiation beam may not exactly correspond to the desired pattern in the target portion of the substrate, for example if the pattern includes phase-shifting features or so called assist features. Generally, the pattern imparted to the radiation beam will correspond to a particular functional layer in a device being created in the target portion, such as an integrated circuit.

[0025] The patterning device may be transmissive or reflective. Examples of patterning devices include masks, programmable mirror arrays, and programmable LCD panels. Masks are well known in lithography, and include mask types such as binary, alternating phase-shift, and attenuated phase-shift, as well as various hybrid mask types. An example of a programmable mirror array employs a matrix arrangement of small mirrors, each of which can be individually tilted so as to reflect an incoming radiation beam in different directions. The tilted mirrors impart a pattern in a radiation beam which is reflected by the mirror matrix.

[0026] The term "projection system" used herein should be broadly interpreted as encompassing any type of projection system, including refractive, reflective, catadioptric, magnetic, electromagnetic and electrostatic optical systems, or any combination thereof, as appropriate for the exposure radiation being used, or for other factors such as the use of an immersion liquid or the use of a vacuum. Any use of the term "projection lens" herein may be considered as synonymous with the more general term "projection system".

[0027] As here depicted, the apparatus is of a transmissive type (e.g. employing a transmissive mask). Alternatively, the apparatus may be of a reflective type (e.g. employing a programmable mirror array of a type as referred to above, or employing a reflective mask).

[0028] The lithographic apparatus may be of a type having two (dual stage) or more substrate tables or "substrate supports" (and/or two or more mask tables or "mask supports"). In such "multiple stage" machines the additional tables or supports may be used in parallel, or preparatory steps may be carried out on one or more tables or supports while one or more other tables or supports are being used for exposure.

[0029] The lithographic apparatus may also be of a type wherein at least a portion of the substrate may be covered by a liquid having a relatively high refractive index, e.g. water, so as to fill a space between the projection system and the substrate. An immersion liquid may also be applied to other spaces in the lithographic apparatus, for example, between the mask and the projection system. Immersion techniques can be used to increase the numerical aperture of projection systems. The term "immersion" as used herein does not mean that a structure, such as a substrate, must be submerged in liquid, but rather only means that a liquid is located between the projection system and the substrate during exposure.

[0030] Referring to Figure 1, 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 passed from the source SO to the illuminator IL with the aid of a beam delivery system BD including, for example, suitable directing mirrors and/or a beam expander. In other cases the source may be an integral part of the lithographic apparatus, for example when the source is a mercury lamp. The source SO and the illuminator IL, together with the beam delivery system BD if required, may be referred to as a radiation system.

[0031] The illuminator IL may include an adjuster AD configured to adjust the angular intensity distribution of the radiation beam. Generally, at least the outer and/or inner radial extent (commonly referred to as σ-outer and σ-inner, respectively) of the intensity distribution in a pupil plane of the illuminator can be adjusted. In addition, the illuminator IL may include various other components, such as an integrator IN and a condenser CO. The illuminator may be used to condition the radiation beam, to have a desired uniformity and intensity distribution in its cross-section.

[0032] The radiation beam B is incident on the patterning device (e.g., mask) MA, which is held on the patterning device support (e.g., mask table MT), and is patterned by the patterning device. Having traversed the patterning device (e.g. mask) MA, the radiation beam B passes through the projection system PS, which focuses the beam onto a target portion C of the substrate W. With the aid of the second positioning device PW and position sensor IF (e.g. an interferometric device, linear encoder or capacitive sensor), the substrate table WT can be moved accurately, e.g. so as to position different target portions C in the path of the radiation beam B. Similarly, the first positioning device PM and another position sensor (which is not explicitly depicted in Figure 1) can be used to accurately position the patterning device (e.g. mask) MA with respect to the path of the radiation beam B, e.g. after mechanical retrieval from a mask library, or during a scan. In general, movement of the patterning device support (e.g. mask table) MT may be realized with the aid of a long-stroke module (coarse positioning) and a short-stroke module (fine positioning), which form part of the first positioning device PM. Similarly, movement of the substrate table WT or "substrate support" 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 scanner) the patterning device support (e.g. mask table) MT may be connected to a short-stroke actuator only, or may be fixed. Patterning device (e.g. mask) MA and substrate W may be aligned using mask alignment marks Μ1, M2 and substrate alignment marks PI, P2. Although the substrate alignment marks as illustrated occupy dedicated target portions, they may be located in spaces between target portions (these are known as scribe-lane alignment marks). Similarly, in situations in which more than one die is provided on the patterning device (e.g. mask) MA, the mask alignment marks may be located between the dies.

[0033] The depicted apparatus could be used in at least one of the following modes: [0034] 1. In step mode, the patterning device support (e.g. mask table) MT or "mask support" and the substrate table WT or "substrate support" are kept essentially stationary, while an entire pattern imparted to the radiation beam is projected onto a target portion C at one time (i.e. a single static exposure). The substrate table WT or "substrate support" 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. (0035] 2. In scan mode, the patterning device support (e.g. mask table) MT or "mask support" and the substrate table WT or "substrate support" 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 or "substrate support" relative to the patterning device support (e.g. mask table) MT or "mask support" may be determined by the (de-)magnification and image reversal characteristics of the projection system PS. In scan mode, the maximum size of the exposure field limits the width (in the non-scanning direction) of the target portion in a single dynamic exposure, whereas the length of the scanning motion determines the height (in the scanning direction) of the target portion. (0036] 3. In another mode, the patterning device support (e.g. mask table) MT or "mask support" is kept essentially stationary holding a programmable patterning device, and the substrate table WT or "substrate support" is moved or scanned while a 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 desired after each movement of the substrate table WT or "substrate support" or in between successive radiation pulses during a scan. This mode of operation can be readily applied to maskless lithography that utilizes programmable patterning device, such as a programmable mirror array of a type as referred to above. (0037] Combinations and/or variations on the above described modes of use or entirely different modes of use may also be employed. (0038] Figure 2 depicts a part of the lithographic apparatus of Figure 1. The patterning device stage 1 supports a patterning device. The patterning device stage 1 is located above a projection system 3. Under the projection system 3, a substrate stage 4 carrying a substrate 5 is positioned. The patterning device stage 1 and the substrate stage 4 are movable with high accuracy so that during projection the patterning device stage 1 and substrate stage 4 can be moved with a scanning movement with respect to the projection system 3 to project a projection beam having a pattern imparted by the reticle 2 on a target portion of the substrate 5 supported by the substrate stage 4. (0039] The projection system 3 is supported by a metrology frame or metro-frame 6 which is a substantially stationary frame. The metro-frame 6 is mounted on a base frame 7 by a number of air mounts 8. These air mounts 8 may include active or passive damping devices so that any vibrations in the base frame 7 are not passed on to the metro-frame 6. In this way, the projection system 3 is substantially isolated from vibrations in the base frame 7 in order to decrease imaging errors such as overlay or focus errors in the projection of the patterned beam on the substrate 5 due to vibration/movement of the projection system 3.

[0040] However, the movement of the patterning device stage 1 may cause gas flows and pressure waves, i.e. gas borne noise, around the patterning device stage 1 and as a result in the process area, i.e. the area in which the patterning device stage 1, the projection system 3 and the substrate stage 4 are arranged. The movements may also cause vibrations of the patterning device support of the patterning device stage. This structure borne noise may also cause disturbances of elements sensitive therefore, for instance the projection system 3.

[0041] The structure borne noise may cause vibrations of these element, which again may result in a gas borne noise, i.e. gas flows or pressure waves. This indirect gas borne noise is thus indirectly caused by the movements of the patterning device stage.

[0042] Some of the gas flows and/or pressure waves resulting from the movement of the patterning device stage 1 may propagate in the direction of the projection system 3 or the metro-frame 6 supporting the projection system 3.

[0043] In a connventional lithographic apparatus, the projection system 3 or metro-frame 6 may be excited by these gas flows and/or pressure waves which may result in movements of the projection system, in particular the lenses and/or other optical elements in the projection system 3. These movements may influence the radiation beam passing through the projection system 3, resulting in overlay and/or focus errors and/or fading. This is undesirable.

[0044] In an embodiment of the present application such parts, e.g. projection system and metro-frame, are regarded to be sensitive for gas flows and/or pressure waves. In this embodiment, in particular, parts of the lithographic apparatus which when exposed to gas flows and/or pressure waves are influenced such that the accuracy of projection, e.g. overlay, fading and/or focus, of the lithographic apparatus is decreased, are regarded to be sensitive to gas flows and/or pressure waves. Such parts may for instance include sensors or sensor target objects, such as a interferometers or encoder grating or grid, of a stage position measurement system.

[0045] In the lithographic apparatus of Figure 2, a shield device is provided in the form of a shield plate 9, which is arranged between the reticle stage 1 on the one hand and the projection system 3 and metro-frame 6 on the other hand. The shield plate 9 is preferably a relatively compliant and heavy plate configured to substantially absorb or reflect the gas flows and/or pressure waves, and is preferably mounted on the base frame 7 so that resulting reaction forces are led to other parts of the lithographic apparatus. When desired, the shield plate 9 may be flexibly supported in order to isolate the shield plate 9 structurally from the base frame 7 to avoid generation of gas flows and/or pressure waves by the shield plate 9 itself. By the provision of a shield plate 9, all gas flows and/or pressure waves running in the direction of the projection system 3 or metro-frame 6 will at least for a large extent be absorbed or reflected by the shield plate 9 and thus not reach the projection system 3 or metro-frame 6. As a result, the projection system 3 and/or metro-frame 6 may not or substantially less be excited by the gas flows and/or pressure waves and the accuracy of projection may not be negatively influenced by the presence of the gas flows and/or pressure waves caused by the gas borne and structure borne noise of the patterning device stage 1.

[0046] The shield plate 9 preferably extends between the whole area in which the patterning device stage 1 can be moved, at least during the exposure phase, and the location of the projection system 3 and preferably also the metro-frame 6 in the case the metro-frame is sensitive to the gas flows and/or pressure waves. At the location where the patterned beam of radiation crosses the shield plate 9, an opening 10 is provided in the shield plate 9 in order for the patterned beam of radiation to pass through the shield plate 9.

[0047] The shield plate and alternative embodiments thereof are described in more detail in the commonly assigned US patent application 11/785,751, filed on April 19,2007, the contents of which is herein incorporated in its entirety by reference.

[0048] Due to the presence of opening 10 in the shield plate, or any other opening between the compartment 11 in which the patterning device stage 1 is mounted and the compartment 12 in which the projection system 3 is arranged, it is still possible that the gas flows and/or pressure waves may reach the projection system compartment 12. This is also a result of the reverberation of gas flows and/or pressure waves reverberate stage compartment 11. As a result, the gas flows and/or pressure waves may still enter the projection system compartment through the opening 10 causing excitation of the projection system 3.

[0049] According to an embodiment of the present invention, it is proposed to arrange i a number of panel absorbers 13, 14, 15, and 16 in the lithographic apparatus. These panel absorbers act as passive noise dampeners.

[0050] In Figure 3, an example of a panel absorber 20 is shown in more detail. A panel absorber 20 is a resonant system including two plate shaped objects 21 spaced from each other, for instance by spacers 22. Between the two plate-shaped objects a sound absorbing material 23, such as glass fiber or foam material, may be placed. In an alternative embodiment, the space between the plate-shaped objects may be filled with gas, for instance air. In an embodiment the plate shaped objects 21 may be perforated to obtain a different behavior of the panel absorber.

[0051] A benefit of a panel absorber over a body of noise absorbing material, such a foam material, is that a panel absorber may have a relatively broadband effective frequency range that may be tuned to the desired frequency range. The effective frequency range is typically much lower than the effective frequency range of a separate body of foam material. This has the result that for the application of an embodiment of the present invention in which the relevant frequency range is typically a few hundred Hz, the thickness of a panel absorber may be limited to a couple of centimeters, while the thickness of a separate body of foam material would be considerably larger.

[0052] In order to achieve high damping by the panel absorbers, the mechanical impedance should preferably be chosen approximately equal to the impedance of the gas in which the pressure waves propagate (in the present example air) to obtain an adequate coupling between the air pressure and the panel vibration.

[0053] Now again referring to Figure 2, the panel absorbers 13, 14, 15 and 16 may be placed at different suitable locations. The panel absorbers 13 are arranged on the side wall of the reverberate stage compartment 11, the panel absorbers 14 are arranged on the shield plate 9 at the side of the reverberate stage 1, the panel absorbers 15 are arranged on the top cover of the reverberate stage and the panel absorbers 16 are arranged on the projection system 3 and. In alternative embodiments, one or more of the panel absorbers 13, 14, 15, 16 may be omitted or may be arranged at other or further suitable locations, such as a wall of the projection system compartment 12, or at the bottom side of the shield plate 9.

[0054] By provision of panel absorbers in the lithographic apparatus, the gas borne noise, i.e. the pressure waves or gas flows through caused by movement of the patterning device stage 1 may be absorbed. This gas borne noise may be direct gas borne noise, i.e. gas flows or pressure waves directly caused by the movement of the patterning device stage 1, but also indirect gas borne noise, i.e. gas flows or pressure waves resulting from elements vibrating due to structure borne noise.

[0055] Due to the presence of the panel absorbers 13 and 14 and 15 in the patterning device stage compartment 11, acoustic reverberations are strongly reduced and hence the overall sound pressure levels in the patterning device stage are decreased. Because of this, less gas flows and/or pressure waves may pass the opening 10.

[0056] When gas flows and/or pressure waves would pass the opening 10 or any other gap between the patterning device stage compartment 11 and the projection system compartment 12, and enter into the projection system compartment 12, the gas flows and/or pressure waves may be damped by the panel absorbers 16 which are mounted on the projection system 3. The panel absorbers 16 are arcuate to correspond with the cylindrical outer surface of the projection system 3. Any other suitable shape may also be used.

[0057] Although panel absorbers are preferred as panel-shaped noise absorbing devices, any other type of suitable devices such as panel-shaped bodies of foam material may also be applied in another embodiment of the invention.

[0058] In an embodiment of the lithographic apparatus, panel-shaped noise absorbing devices may be provided for damping the gas borne noise caused by a movable object such as a patterning device stage, while the shield plate 9 may be omitted.

[0059] Figure 4 shows a part of a lithographic apparatus, in particular a side view of a patterning device stage 30 supporting a patterning device 31 in accordance with an embodiment of the invention. Such patterning device stage 30 typically is provided to make a scanning movement along a direction of movement. During this scanning movement, the air, in the direction of movement, in front of the patterning device stage 30 may be pressed away while at the same time air may be sucked into the space created by the patterning device stage 30 at the back of the patterning device stage 30. This movement may cause gas borne noise which may propagate towards the projection system as described in relation to the embodiment of Figure 2.

[0060] The patterning device stage 30 is arranged between two frame plates 32 defining a patterning device stage compartment 33 there-between. Due to the presence of these plates 32 or any other construction element present in the lithographic apparatus which delimits the space wherein the patterning device stage 30 is arranged, the movement of the patterning device stage 30 may push relatively more air in front of the patterning device stage 30 and suck more air in the space behind the patterning device stage 30. Other constructions which may delimit the area in which reticle stage 30 is moved, may for instance be an illumination module, balance masses, noise shield plates and such.

[0061] In the embodiment of Figure 4, a noise absorbing material or object 34 is added to the front and back of the patterning device stage 30 to absorb the gas borne noise created by the movement of the patterning device stage 30. This noise absorbing part/object may be a body of suitable material such as foam material, but also a panel absorber, a labyrinth, a membrane or bellow as shown in Figure 4, or any combination thereof. The presence of such noise absorbing material or object 34 may decrease the amount of noise created by the movement of the patterning device stage 30. As a result, this noise may not reach an element sensitive to this noise such as the projection system.

[0062] Figure 5 shows another arrangement in accordance with an embodiment of the invention, in which the front and back end of the patterning device stage 30 are provided with an aero-dynamical structure or shape to prevent or reduce vortex shedding. The aero-dynamical structure is configured to improve penetration of the stage 30 in gas surrounding the stage 30. In particular the front and back area of the patterning device stage are reduced to reduce the gas resistance with respect to the movement of the patterning device stage 30. Any suitable shape which reduces the gas resistance of the patterning device stage 30 may be used to reduce the gas flows and/or pressure waves caused by movements of the patterning device stage 30 in order to avoid gas bome noise which may excite element sensitive for such noise such as the projection system.

[0063] Figures 6a and 6b show yet another alternative arrangement in accordance with an embodiment of the invention for the reduction of gas bome noise caused by movement of the patterning device stage 30. In the embodiment of Figure 6a and 6b, a first bellows 36 is attached to a first end of the patterning device stage 30 while a second bellows 37 is attached to an opposite end of the patterning device stage in the direction of movement. The first bellows 36 and second bellows 37 are connected to each other via conduit 38.

[0064] In Figure 6a, the patterning device stage 30 is shown in a center position. When the patterning device stage for instance is moved to the right the second bellows 37 is compressed, while the first bellows 36 is extended. The gas, which is pressed out of the second bellows 37 due to the compression of the second bellows 37,-is pressed via the conduit 38 towards the first bellows 36 which extends. Since the internal volume of the first bellows 36, the second bellows 37 and conduit 38 remains the same, the volume of gas pressed away in front of the patterning device stage 30 may fill the empty space left behind the patterning device stage at the opposite side.

[0065] In Figure 6b, the patterning device stage is shown when it has been moved to the right. It can be seen that the first bellows 36 is extended, while the second bellows 37 is compressed. When the patterning device stage 30 is moved in the opposite direction, the gas in the enclosed system will flow back from the left side of the patterning device stage 30 to the right side of the patterning device stage 30 via the conduit 38.

[0066] Since the front and back side in the direction of movement of the patterning device stage 30 are connected to each other with an enclosed gas system, the noise resulting from movement of the reticle stage 30 is substantially reduced. Furthermore, since the gas is present in the enclosed gas system any flows or pressure waves may substantially remain in the enclosed system and these flows or pressure waves may not reach the projection system or any other element sensitive to this noise.

[0067] The above described noise reducing dampeners (or noice reducing device) may be applied alone or in combination to obtain an effective noise reduction of the noise created by movement of the patterning device stage 30 or any movable object in general. In addition thereto, or as an alternative, it is possible to provide an enclosed gas system wherein the movable object is moved containing a gas having a lower density than the normally used gas, for instance a vacuum environment instead of air under atmospheric pressure. For example, a pressure of the enclosed gas in the enclosed gas system is lower than 1 atm. Also, it is possible to decrease or adapt the surface of the element sensitive for the gas borne noise in order to decrease the influence of the noise.

[0068] In an embodiment, the passive noise dampener comprises a movable part, configured to move in an opposite direction of the movable patterning device stage such that a balance of gas flow, or pressure waves or both created by both the movable part and the movable patterning device stage may be obtained. The movable part may be structurally designed so to substantially balance the gas flow, or pressure waves or both created by the movable patterning device stage.

[0069] Although specific reference may be made in this text to the use of lithographic apparatus in the manufacture of ICs, it should be understood that the lithographic apparatus described herein may have other applications, such as the manufacture of integrated optical systems, guidance and detection patterns for magnetic domain memories, flat-panel displays, liquid-crystal displays (LCDs), thin-film magnetic heads, etc. The skilled artisan will appreciate that, in the context of such alternative applications, any use of the terms "wafer" or "die" herein may be considered as synonymous with the more general terms "substrate" or "target portion", respectively. The substrate referred to herein may be processed, before or after exposure, in for example a track (a tool that typically applies a layer of resist to a substrate and develops the exposed resist), a metrology tool and/or an inspection tool. Where applicable, the disclosure herein may be applied to such and other substrate processing tools. Further, the substrate may be processed more than once, for example in order to create a multi-layer IC, so that the term substrate used herein may also refer to a substrate that already contains multiple processed layers.

[0070] Although specific reference may have been made above to the use of embodiments of the invention in the context of optical lithography, it will be appreciated that the invention may be used in other applications, for example imprint lithography, and where the context allows, is not limited to optical lithography. In imprint lithography a topography in a patterning device defines the pattern created on a substrate. The topography of the patterning device may be pressed into a layer of resist supplied to the substrate whereupon the resist is cured by applying electromagnetic radiation, heat, pressure or a combination thereof. The patterning device is moved out of the resist leaving a pattern in it after the resist is cured.

[0071] The terms "radiation" and "beam" used herein encompass all types of electromagnetic radiation, including ultraviolet (UV) radiation (e.g. having a wavelength of or about 365,248, 193,157 or 126 nm) and extreme ultra-violet (EUV) radiation (e.g. having a wavelength in the range of 5-20 nm), as well as particle beams, such as ion beams or electron beams.

[0072] The term "lens", where the context allows, may refer to any one or combination of various types of optical components, including refractive, reflective, magnetic, electromagnetic and electrostatic optical components.

[0073] While specific embodiments of the invention have been described above, it will be appreciated that the invention may be practiced otherwise than as described. For example, the invention may take the form of a computer program containing one or more sequences of machine-readable instructions describing a method as disclosed above, or a data storage medium (e.g. semiconductor memory, magnetic or optical disk) having such a computer program stored therein.

[0074] The descriptions above are intended to be illustrative, not limiting. Thus, it will be apparent to one skilled in the art that modifications may be made to the invention as described without departing from the scope of the clauses set out below. Other aspects of the invention are set out as in the following numbered clauses: 1. A lithographic apparatus comprising: an illumination system configured to condition a radiation beam; a patterning device support constructed to support a patterning device, the patterning device being capable of imparting the radiation beam with a pattern in its cross-section to form a patterned radiation beam; a substrate table constructed to hold a substrate; a projection system configured to project the patterned radiation beam onto a target portion of the substrate, and a passive noise dampener configured to dampen gas borne noise caused by movement of a movable object of the lithographic apparatus. 2. The lithographic apparatus of clause 1, wherein the passive noise dampener is arranged on the movable object. 3. The lithographic apparatus of clause 2, wherein the passive noise dampener comprises an aero-dynamical structure positioned on the movable object to improve penetration of the object in gas along a direction of movement of the object, the aero-dynamical structure having a frontal area in the direction of movement that is smaller than an area of a maximum dimension of the movable object. 2. The lithographic apparatus of clause 1, wherein the passive noise dampener comprises a panel absorber, a labyrinth, a membrane, or bellows or any combination thereof, the bellows provided on a first side, or a second side, opposite to the first side, or both the first side and the second side of the movable object. 5. The lithographic apparatus of clause 1, wherein the passive noise dampener comprises a movable part, configured to move in an opposite direction of the movable object, the movable part and the movable object configured to obtain a balancing of gas flow, or pressure waves or both. 4. The lithographic apparatus of clause 1, wherein the passive noise dampener comprises a first space located before and a second space located after the movable object in the direction of movement, the enclosed gas system to guide gas pressed out of the first space to the second space during movement of the movable object. 7. The lithographic apparatus of clause 6, wherein a first bellows is connected to a first side of the movable object and a second bellows is connected to a second side, opposite to the first side, of the movable object, wherein the first and second bellows are connected to each other. 6. The lithographic apparatus of clause 1, wherein the passive noise dampener comprises an enclosed gas system in which the movable object is arranged, wherein a pressure of the enclosed gas in the enclosed gas system is lower than 1 atm. 9. The lithographic apparatus of clause 1, wherein the passive noise reducing dampener comprise a noise panel-shaped absorbing device. 8. The lithographic apparatus of clause 1, wherein the panel-shaped noise absorbing devices comprises foam material. 9. The lithographic apparatus of clause 1, wherein the panel-shaped noise absorbing device is a panel absorber. 10. The lithographic apparatus of clause 9, wherein panel-shaped absorbing device is flat or arched. 11 The lithographic apparatus of clause 9, wherein the panel-shaped noise absorbing device is mounted in a compartment of the lithographic apparatus in which the movable object is movable. 12. The lithographic apparatus of clause 9, wherein the lithographic apparatus further comprises a noise shield arranged between a source of the gas borne noise and an element sensitive to the gas borne noise, and wherein the panel-shaped absorbing device is mounted on the noise shield. 13. The lithographic apparatus of clause 9, wherein the panel-shaped noise absorbing device is mounted in a compartment of the lithographic apparatus in which an element sensitive to the gas borne noise is arranged. 14. The lithographic apparatus of clause 9, wherein the panel-shaped noise absorbing device surrounds the element. 17. The lithographic apparatus of clause 16, wherein the element is the projection system. 18. The lithographic apparatus of clause 9, wherein the panel-shaped noise absorbing device is mounted on the movable object. 19. The lithographic apparatus of clause 1, wherein the movable object is the patterning device support. 20. A method of reducing gas borne noise in a lithographic apparatus, the method comprising dampening gas borne noise caused by movement of a movable object of the lithographic apparatus. 21. A device manufacturing method comprising: projecting a patterned beam of radiation onto a substrate using a lithographic apparatus; and dampening gas borne noise caused by movement of a movable object of the lithographic apparatus. 22. The method of clause 21, wherein the movable object is patterning device support configured to support a patterning device, the patterning device configured to pattern a beam of radiation to form the patterned beam of radiation.

Claims (1)

1. Een lithografieinrichting omvattende: een belichtinginrichting ingericht voor het leveren van een stralingsbundel; een drager geconstrueerd voor het dragen van een patroneerinrichting, welke patroneerinrichting in staat is een patroon aan te brengen in een doorsnede van de stralingsbundel ter vorming van een gepatroneerde stralingsbundel; een substraattafel geconstrueerd om een substraat te dragen; en een projectieinrichting ingericht voor het projecteren van de gepatroneerde stralingsbundel op een doelgebied van het substraat, met het kenmerk, dat de substraattafel is ingericht voor het positioneren van het doelgebied van het substraat in een brandpuntsvlak van de proj ectieinri chting.