Lithography equipment

Abstract

The present invention discloses a lithographic apparatus, comprising: an illumination system configured to condition a radiation beam; a pattern forming device (601) configured to impart a pattern to the radiation beam in a cross section of the radiation beam to form a patterned radiation beam; a pellicle (602) configured to cover a surface of the pattern forming device (601); a substrate stage configured to hold a substrate; a projection system configured to project the patterned radiation beam onto a target portion of the substrate when the substrate is held by the substrate stage, wherein the projection system comprises one or more optical elements; a first set of one or more outlets (603) for outputting a first fluid into a first region, wherein the first region is adjacent to and / or comprises the pellicle (602); and a second set of one or more outlets (605) configured to output a second fluid into a second region, wherein the second region comprises one or more optical elements of the projection system; and wherein the second fluid is different from the first fluid. Advantageously, the fluid in the first region protects the pellicle (602) from being damaged by the fluid in the second region. It is thus possible to use a pellicle that would otherwise be damaged by the fluid in the second region.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to European application 18175342.7 filed on May 31, 2018, which is incorporated herein by reference in its entirety. Technical Field

[0003] The present invention relates to a lithographic apparatus. More particularly, the technology disclosed herein relates to providing a pellicle for use with EUV radiation in a lithographic apparatus. Background Art

[0004] A lithographic apparatus is a machine that applies a desired pattern to a substrate, typically a target portion of the substrate. A lithographic apparatus can be used, for example, in the manufacture of integrated circuits (ICs). In the case of manufacturing ICs, a pattern forming device, alternatively referred to as a mask or reticle, can be used to generate a circuit pattern to be formed on a single layer of the IC. This pattern can be transferred to a target portion (e.g., including a portion of a die, one or several dies) on a substrate (e.g., a silicon wafer). Typically, the transfer of the pattern is performed by imaging the pattern onto a layer of a radiation-sensitive material (resist) disposed on the substrate. Typically, a single substrate will contain a network of adjacent target portions that are patterned in succession. Known lithographic apparatus include so-called steppers, in which each target portion is irradiated by exposing the entire pattern to the target portion at once, and so-called scanners, in which each target portion is irradiated by scanning the pattern along a given direction (the "scanning" direction) with a radiation beam, while simultaneously scanning the substrate in a direction parallel or antiparallel to that direction.

[0005] A theoretical estimate of the limit of pattern printing can be given by the Rayleigh criterion for resolution, as shown in equation (1):

[0006] CD=k_1*λ / NA(1)

[0007] where λ is the wavelength of the radiation used, NA is the numerical aperture of the projection system used to print the pattern, k1 is a process-dependent adjustment factor also known as the Rayleigh constant, and CD is the feature size (or critical dimension) of the printed features. From equation (1), it follows that a reduction in the minimum printable size of a feature can be obtained in three ways: by shortening the exposure wavelength λ, by increasing the numerical aperture NA, or by reducing the value of k1.

[0008] In order to shorten the exposure wavelength and thus reduce the minimum printable size, it has been proposed to use extreme ultraviolet (EUV) radiation sources. EUV radiation is electromagnetic radiation with a wavelength in the range of 4 to 20 nm, for example in the range of 13 to 14 nm, or for example in the range of 4 to 10 nm (such as 6.7 nm or 6.8 nm). Available sources include, for example, laser-generated plasma sources, discharge plasma sources, or sources based on synchrotron radiation provided by electron storage rings.

[0009] EUV radiation can be generated using a plasma. A radiation system for generating EUV radiation may include: a laser for exciting a fuel to provide a plasma; and a source collector module for containing the plasma. The plasma can be formed, for example, by directing a laser beam at a fuel, such as a droplet of a suitable material (e.g., tin), or a flow of a suitable gas or vapor (such as Xe gas or Li vapor). The formed plasma emits output radiation, such as EUV radiation, which is collected using a radiation collector. The radiation collector may be a mirrored normal-incidence radiation collector that receives radiation and focuses the radiation into a beam. The source collector module may include an enclosed structure or chamber arranged to provide a vacuum environment to support the plasma. Such a radiation source is typically referred to as a laser produced plasma (LPP) radiation source.

[0010] A known problem in EUV lithography apparatus is the contamination of the patterning device. In an EUV lithography apparatus, flushing gases flow at high speed towards the patterning device and can carry molecules and particles up to micrometer size. In certain lithography apparatus, a pellicle may be provided to protect the patterning device. A pellicle is a transparent membrane covering the patterning device. However, the use of a pellicle with EUV radiation is a problem because EUV radiation is highly absorbed by the pellicle, thereby reducing the efficiency of the system. Summary of the invention

[0011] According to a first aspect of the present invention, there is provided a lithographic apparatus, comprising: an irradiation system configured to condition a radiation beam; a pattern forming device configured to impart a pattern to the radiation beam in a cross section of the radiation beam to form a patterned radiation beam; a pellicle configured to cover a surface of the pattern forming device; a substrate stage configured to hold a substrate; a projection system configured to project the patterned radiation beam onto a target portion of a substrate when the substrate is held by the substrate stage, wherein the projection system comprises one or more optical elements; one or more outlets of a first group for outputting a first fluid into a first region, wherein the first region is adjacent to and / or includes The projection system further comprises a projection device, the projection system comprising a pellicle, a first group of one or more outlets, a second group of one or more outlets, configured to output a second fluid into a second region, the second region comprising one or more optical elements of the projection system; and wherein the second fluid is different from the first fluid; and, optionally, wherein the patterning device, the pellicle, the first group of one or more outlets, the second group of one or more outlets and the substrate table are arranged such that, in use, a patterned radiation beam travels from the patterning device, then passes through the pellicle adjoining and / or included by the first region, then passes through the second region, and then reaches a substrate held by the substrate table.

[0012] In one embodiment, one or more outlets of the first group may be configured to provide a first gas environment in the first region, wherein the first gas environment protects the diaphragm from the second region, or in other words, the first gas environment prevents fluid in the second region from reaching the diaphragm.

[0013] Preferably, the first fluid is a gas that is inert and / or chemically neutral to the pellicle.

[0014] Preferably, the first fluid comprises one or more of helium, neon, argon or nitrogen.

[0015] Preferably, the second fluid comprises a gas and / or plasma, such as a hydrogen plasma, for preventing oxidation and contamination of one or more optical elements of the projection system.

[0016] Preferably, the second fluid comprises hydrogen radicals.

[0017] According to an embodiment of the present invention, the second fluid may include a gas and / or a plasma that degrades the surface film.

[0018] Preferably, the lithographic apparatus further comprises a patterning device support arranged to support the patterning device, wherein the pellicle is coupled to the patterning device support.

[0019] Preferably, the second group of one or more outlets are arranged between the first group of one or more outlets and one or more optical elements of the projection system.

[0020] Preferably, the lithographic apparatus further comprises a first set of one or more inlets arranged in the first region for removing fluid from the first region.

[0021] Preferably, the inlet of the first set is arranged on an opposite side of the diaphragm to the outlet of the first set so that, in use, there is a cross-flow of the first fluid across the diaphragm.

[0022] Preferably, the lithographic apparatus further comprises a second set of one or more inlets, the second set of one or more inlets being arranged in the second region for removing fluid from the second region.

[0023] Preferably, the inlet of the second set is arranged on an opposite side of the projection system to the outlet of the second set, so that in use there is a cross-flow of the second fluid across the projection system.

[0024] Preferably, the pellicle is carbon-based. In this embodiment, the first fluid may comprise a carbon-containing gas, ie a gas comprising carbon compounds.

[0025] Preferably, the surface film comprises one or more of carbon nanotubes and diamonds.

[0026] Preferably, the illumination system is configured to condition the extreme ultraviolet (EUV) radiation beam.

[0027] Preferably, one or more of said one or more optical elements are mirrors.

[0028] Preferably, the lithographic apparatus further comprises a control system configured to select the first fluid to be output from the first set of one or more outlets depending on the type of pellicle being used.

[0029] According to an embodiment, the lithographic apparatus may further include a first fluid supplier containing the first fluid and a second fluid supplier containing the second fluid, the first fluid supplier being in fluid connection with one or more outlets of the first group, and the second fluid supplier being in fluid connection with one or more outlets of the second group. The first fluid supplier and / or the second fluid supplier may, for example, include a first respectively second container, but may alternatively or additionally also include a first respectively second fluid connector for connecting a fluid supply system.

[0030] According to a second aspect of the present invention, a method is provided, comprising: regulating a radiation beam; imparting a pattern to the radiation beam in a cross-section of the radiation beam using a pattern forming device to form a patterned radiation beam, wherein a pellicle covers a surface of the pattern forming device; projecting the patterned radiation beam onto a target portion of a substrate by a projection system, wherein the projection system comprises one or more optical elements; outputting a first fluid into a first region by one or more outlets of a first group, wherein the first region is adjacent to and / or includes the pellicle; and outputting a second fluid into a second region by one or more outlets of a second group, wherein the second region includes one or more optical elements of the projection system; wherein the second fluid is different from the first fluid; and, optionally, wherein the pattern forming device, the pellicle, the one or more outlets of the first group, the one or more outlets of the second group and the substrate are arranged so that the patterned radiation beam travels from the pattern forming device, then passes through the pellicle adjacent to and / or included by the first region, then passes through the second region, and then reaches the substrate held by the substrate stage.

[0031] In one embodiment, outputting the first fluid into the first region may result in generating a first gas environment in the first region that protects the diaphragm from the second region, or, in other words, generates a first gas environment that prevents the fluid in the second region from reaching the diaphragm.

[0032] Preferably, the method is performed by a lithographic apparatus according to the first aspect of the invention.

[0033] Preferably, the method further comprises selecting the first fluid output by the first set of one or more outlets depending on the type of diaphragm being used.

[0034] In embodiments where the pellicle is carbon-based, the first fluid may include a carbon-containing gas.

[0035] According to a third aspect of the present invention, there is provided a lithographic apparatus, comprising: an irradiation system configured to condition a radiation beam; a pattern forming device configured to impart a pattern to the radiation beam in a cross section of the radiation beam to form a patterned radiation beam; a substrate stage configured to hold a substrate in a substrate region; a pellicle configured to cover a surface of the substrate; a projection system configured to project the patterned radiation beam onto a target portion of the substrate when the substrate is held by the substrate stage, wherein the projection system comprises one or more optical elements; a second group of one or more outlets configured to output a second fluid into a second region, wherein the second region comprises one or more optical elements of the projection system; and a third group of one or more outlets for outputting a third fluid into a third region, wherein the third region is adjacent to and / or comprises the substrate region; and wherein the second fluid is different from the third fluid. The third group of one or more outlets may, for example, be configured to provide a third gas environment in the third region, wherein the third gas environment protects the substrate from the second region.

[0036] In one embodiment, the substrate region comprises a membrane, the membrane being configured to cover a surface of the substrate, and wherein the third region adjoins and / or comprises the membrane. In this embodiment, the one or more outlets of the third group are configured to provide a third gas environment in the third region, the third gas environment protecting the membrane from the second region.

[0037] Optionally, the pattern forming device, the projection system, the one or more outlets of the second group, the one or more outlets of the third group and the substrate table are arranged such that, in use, a patterned radiation beam travels from the pattern forming device, through the projection system including the second area, through the third area, and then onto a substrate held by the substrate table.

[0038] Preferably, the third fluid is a gas that is inert and / or chemically neutral towards the substrate.

[0039] Preferably, the third fluid comprises one or more of helium, neon, argon or nitrogen.

[0040] According to an embodiment of the present invention, the second fluid includes a gas and / or a plasma that degrades the substrate.

[0041] Preferably, the second fluid comprises a gas and / or plasma, such as a hydrogen plasma, for preventing oxidation and contamination of one or more optical elements of the projection system.

[0042] Preferably, the second fluid comprises hydrogen radicals.

[0043] Preferably, the lithographic apparatus further comprises a third set of one or more inlets arranged in the third region for removing fluid from the third region.

[0044] Preferably, the third set of one or more inlets are arranged on an opposite side of the substrate to the third set of one or more outlets so that, in use, there is a cross-flow of the third fluid across the substrate.

[0045] Preferably, the lithographic apparatus further comprises a second set of one or more inlets, the second set of one or more inlets being arranged in the second region for removing fluid from the second region.

[0046] Preferably, the second set of one or more inlets is arranged on an opposite side of the projection system to the second set of one or more outlets, so that in use there is a cross-flow of the second fluid across the projection system.

[0047] Preferably, the illumination system is configured to condition an extreme ultraviolet (EUV) radiation beam.

[0048] Preferably, one or more of said one or more optical elements are mirrors.

[0049] The lithographic apparatus may further comprise a control system configured to select a third fluid to be output from the third set of one or more outlets depending on a type of substrate or membrane being used.

[0050] According to one embodiment, the lithography device may also include a second fluid supplier containing the second fluid and a third fluid supplier containing the third fluid, wherein the second fluid supplier is fluidically connected to one or more outlets of the second group, and the third fluid supplier is fluidically connected to one or more outlets of the third group.

[0051] The third aspect of the present invention may be applied in combination with the first aspect and / or the second aspect of the present invention.

[0052] According to a fourth aspect of the present invention, a method is provided, comprising: adjusting a radiation beam; imparting a pattern to the radiation beam in a cross section of the radiation beam by a pattern forming device to form a patterned radiation beam; projecting the patterned radiation beam onto a target portion of a substrate by a projection system, the substrate being held in a substrate region, wherein the projection system comprises one or more optical elements; outputting a second fluid into a second region by one or more outlets of a second group, the second region comprising one or more optical elements of the projection system; and outputting a third fluid into a third region by one or more outlets of a third group, wherein the third region is adjacent to and / or comprises the substrate region; and wherein the second fluid is different from the third fluid. The third fluid output to the third region may, for example, provide a third gas environment in the third region, the third gas environment protecting the substrate from the influence of the second region.

[0053] In one embodiment, the substrate region may include a membrane configured to cover a surface of the substrate, and wherein the third region is adjacent to and / or includes the membrane. In this embodiment, the third fluid output into the third region may, for example, provide a third gas environment in the third region, the third gas environment protecting the membrane from the second region.

[0054] Optionally, the pattern forming device, the diaphragm, the one or more outlets of the second group, the one or more outlets of the third group and the substrate are arranged so that the patterned radiation beam travels from the pattern forming device, passes through the second region, passes through the third region, and then reaches the substrate held by the substrate stage.

[0055] Preferably, the method is performed by the lithography apparatus according to the third aspect of the present invention.

[0056] Preferably, the method further comprises selecting the third fluid output by the third set of one or more outlets depending on the type of substrate or membrane being used.

[0057] The fourth aspect of the present invention may be applied in combination with the first aspect and / or the second aspect of the present invention.

[0058] Additional features and advantages of the present invention and the structure and operation of various embodiments of the present invention are described in more detail below with reference to the accompanying drawings. Note that the present invention is not limited to the specific embodiments described herein. These embodiments are presented herein for illustrative purposes only. Based on the teachings contained herein, additional embodiments will be apparent to those skilled in the relevant art. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] The accompanying drawings, which are incorporated herein and constitute a part of the specification, illustrate the present invention and, together with the description, further serve to explain the principles of the invention and enable those skilled in the relevant art to make and use the invention.

[0060] Figure 1 A known lithographic apparatus is schematically depicted;

[0061] Figure 2 shows the pressure region of a known lithographic apparatus;

[0062] Figure 3 A side view showing features of a known lithographic apparatus;

[0063] Figure 4 A known arrangement of a patterning device assembly and a masking blade is shown;

[0064] Figure 5 A known arrangement of a patterning device assembly and a masking blade is shown in plan view;

[0065] Figure 6 shows an arrangement of a first zone and a second zone of a lithographic apparatus according to an embodiment of the first aspect of the invention;

[0066] Figure 7 is a flowchart of a method according to an embodiment of the second aspect of the present invention;

[0067] Figure 8 showing in side view a substrate table and a third set of outlet and inlet arrangements according to an embodiment of a third aspect of the invention;

[0068] Fig. 9 The plan view shows Figure 8 the arrangement of

[0069] Fig.10 An arrangement of a second zone and a third zone of a lithographic apparatus according to an embodiment of the third aspect of the invention is shown.

[0070] The features and advantages of the present invention will become more apparent from the detailed description set forth below in conjunction with the accompanying drawings, in which like reference numerals identify corresponding elements throughout. In the accompanying drawings, like reference numerals generally indicate identical, functionally similar, and / or structurally similar elements. The drawing in which an element first appears is indicated by the leftmost digit in the corresponding reference numeral. DETAILED DESCRIPTION

[0071] This specification discloses one or more embodiments that incorporate features of the present invention. The disclosed embodiments merely illustrate the present invention. The scope of the present invention is not limited to the disclosed embodiments. The present invention is defined by the claims appended to this specification.

[0072] The described embodiments and references in this specification to "one embodiment," "an embodiment," "an example embodiment," etc. indicate that the described embodiments may include certain features, structures, or characteristics, but each embodiment may not necessarily include the certain features, structures, or characteristics. Furthermore, these phrases do not necessarily refer to the same embodiment. In addition, when a certain feature, structure, or characteristic is described in conjunction with an embodiment, it should be understood that it is within the purview of those skilled in the art to implement such feature, structure, or characteristic in conjunction with other embodiments, whether or not explicitly described.

[0073] Embodiments of the present invention may be implemented with hardware, firmware, software, or any combination thereof. Embodiments of the present invention may also be implemented as instructions stored on a machine-readable medium, which may be read and executed by one or more processors. A machine-readable medium may include any mechanism for storing or transmitting information in a form that can be read by a machine (e.g., a computing device). For example, a machine-readable medium may include a read-only memory (ROM); a random access memory (RAM); a disk storage medium; an optical storage medium; a flash storage device; a propagation signal (e.g., a carrier wave, an infrared signal, a digital signal, etc.) in electrical, optical, acoustic, or other forms, and the like. In addition, firmware, software, resident programs, and / or instructions may be described herein as performing certain actions. However, it should be understood that such descriptions are merely for convenience, and such actions are actually caused by a computing device, a processor, a controller, or other devices that execute firmware, software, routines, instructions, etc.

[0074] However, before describing such embodiments in further detail, it is instructive to present an example environment in which embodiments of the present disclosure may be implemented.

[0075] Figure 1 A lithographic apparatus LAP is schematically shown, comprising: a source collector module SO. The apparatus comprises: an irradiation system (irradiator) configured to condition a radiation beam B (e.g. EUV radiation); a support structure (e.g. mask table) MT constructed to support a pattern forming device (e.g. mask or pattern forming device) MA and connected to a first positioning device PM, which is configured to accurately position the pattern forming device; a substrate table (e.g. wafer stage) WT constructed to hold a substrate (e.g. resist coated wafer) W and connected to a second positioning device PW, which is configured to accurately position the substrate; and a projection system (e.g. reflective projection lens system) PS configured to project a pattern imparted to the radiation beam PB by the pattern forming device MA onto a target portion C (e.g. comprising one or more dies) of the substrate W.

[0076] 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 the radiation.

[0077] The support structure MT includes parts for receiving and holding the patterning device MA 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 the patterning device is held in a vacuum environment). The support structure can use mechanical, vacuum, electrostatic or other clamping techniques to hold the patterning device. The support structure can be, for example, a frame or table that can be fixed or moved as required. The support structure can ensure that the patterning device is at a desired position, for example relative to the projection system PS.

[0078] The term "patterning device" 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, for example to create a pattern in a target portion of a substrate. The pattern imparted to the radiation beam may correspond to a specific functional layer in a device (such as an integrated circuit) created in the target portion.

[0079] 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 masks, alternating phase shift masks, and attenuated phase shift masks, 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 to reflect an incoming radiation beam in different directions. The tilted mirrors impart a pattern in the radiation beam reflected by the matrix of mirrors.

[0080] Similar to the illumination system, the projection 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, as appropriate for the exposure radiation being used, or for other factors such as the use of a vacuum. It may be desirable to use a vacuum for EUV radiation, as other gases may absorb too much radiation. Therefore, a vacuum environment may be provided for the entire beam path with the aid of a vacuum vessel and a vacuum pump.

[0081] As depicted here, the apparatus is of the reflective type (ie employing a reflective mask and reflective optics in the illuminator IL and the projection system PS).

[0082] The lithographic apparatus may be of a type having two (dual stage) or more substrate tables (and / or two or more mask tables). In such a "multi-stage" machine, the extra tables may be used in parallel, or preparatory steps may be performed on one or more tables while one or more other tables are being used for exposure.

[0083] Reference Figure 1 , the illuminator IL receives a beam of EUV radiation from an EUV source SO. Methods for generating EUV radiation include, but are not necessarily limited to, converting a material into a plasma state, the material having at least one element (e.g., xenon, lithium, or tin) having one or more emission lines in the EUV range. In one such method, generally referred to as laser produced plasma ("LPP"), the desired plasma may be generated by irradiating a fuel, such as droplets of a material having the desired line-emitting element, with a laser beam. The EUV source SO may be a laser ( Figure 1 The formed plasma emits output radiation, for example EUV radiation that is collected using a radiation collector disposed within the EUV source.

[0084] The laser and EUV source may be separate entities, for example when a CO2 laser is used to provide the laser beam for fuel excitation. In this case, the radiation beam is transferred from the laser to the EUV source with the aid of a beam delivery system comprising, for example, suitable directional mirrors and / or a beam expander. The laser and the fuel supply may be considered to comprise the EUV radiation source.

[0085] The illuminator IL may include an adjuster for adjusting the angular intensity distribution of the radiation beam. Typically, at least the outer radial extent and / or the inner radial extent (commonly referred to as σ-outer and σ-inner, respectively) of the intensity distribution in a pupil plane of the illuminator may be adjusted. Furthermore, the illuminator IL may include various other components, such as a facet field and a pupil mirror arrangement. The illuminator IL may be used to adjust the radiation beam to have a desired uniformity and intensity distribution in its cross-section.

[0086] The radiation beam PB is incident on the patterning device (e.g. mask) MA held on a support structure (e.g. mask table) MT and is patterned by the patterning device. The patterning device MA may be positioned using a first positioning device, such as an interferometer IF1 and mask alignment marks M1, M2. After being reflected from the patterning device (e.g. mask) MA, the patterned radiation beam PB passes through the projection system PS, which focuses the beam onto a target portion C of the substrate W. With the aid of a second positioning device, such as an interferometer IF2 and substrate alignment marks P1, P2 (e.g. using interferometer devices, linear encoders, or capacitive sensors), the substrate table WT can be accurately moved, for example in order to position different target portions C in the path of the radiation beam PB.

[0087] The depicted device can be used in at least one of the following modes:

[0088] 1. In step mode, while the support structure (e.g. mask table) MT and the substrate table WT are kept substantially stationary, the entire pattern imparted to the radiation beam is projected onto a target portion C at one time (i.e. a single static exposure). Next, the substrate table WT is shifted in the X and / or Y direction so that a different target portion C can be exposed.

[0089] 2. In scan mode, the support structure (e.g. mask table) MT and substrate table WT are scanned synchronously (i.e. single dynamic exposure) as a pattern imparted to the radiation beam is projected onto a target portion C. The speed and direction of the substrate table WT relative to the support structure (e.g. mask table) MT may be determined by the (minimum) magnification and image reversal properties of the projection system PS.

[0090] 3. In another mode, the support structure (e.g. mask table) MT is held substantially stationary, thereby holding the programmable patterning device, and the substrate table WT is moved or scanned, while a pattern imparted to the radiation beam is projected onto a target portion C. In this mode, a pulsed radiation source is typically employed, and the programmable patterning device is updated as required after each movement of the substrate table WT or between successive radiation pulses during a scan. This mode of operation may be readily applicable to maskless lithography using a programmable patterning device, such as a programmable mirror array.

[0091] Figure 2 A known device is shown schematically. Figures 3 to 5 Various parts of the device are shown in more detail. Figure 2The apparatus comprises a first chamber 101 comprising an illumination system IL and a projection system PS. The illumination system IL is configured to condition a radiation beam received from a source SO and the projection system PS is configured to project a patterned radiation beam PB onto a target portion of a substrate W. The first chamber 101 further comprises a patterning device support configured to support the patterning device MA capable of imparting a pattern to the radiation beam in a cross section thereof to form a patterned radiation beam. The second chamber 102 comprises / accommodates a wafer stage, of which only the substrate W is shown for clarity.

[0092] Figure 2 It is shown how the apparatus can be divided into four different vacuum environments VE1 to VE4. The first chamber 101 defines a first vacuum environment VE1, which encloses a pattern forming device platform, of which only the pattern forming device MA is shown for clarity. The first chamber 101 also includes a separator structure 103, which defines two further vacuum environments: VE2, accommodating the illumination system IL; and VE3, accommodating the projection system PS. The vacuum environments VE2 and VE3 can be further divided. The separator structure 103 includes a sleeve 105, which has a hole 104, which is used to transfer the projection beam PB from the illumination system IL to the pattern forming device MA, and to transfer the patterned radiation beam from the pattern forming device MA to the projection system PS. The sleeve 105 is also used to force the gas flow downward (i.e. away from the pattern forming device) and maintain a uniform gas flow to avoid disturbing the EUV radiation intensity. Possibly, the sleeve can be gradually tapered towards the pattern forming device MA. The second chamber 102 defines a vacuum environment VE4 , which is a wafer platform (for clarity, only the substrate W is shown) formed and maintained by respective vacuum vessels and vacuum pumps VP1 and VP2 (which may also be a plurality of vacuum pumps).

[0093] like Figure 2 As shown, vacuum pump VP1 maintains vacuum environment VE1 at a lower pressure than vacuum environments VE2 and VE3. Cleaning gas (e.g., hydrogen, helium, nitrogen, oxygen or argon) is injected into vacuum environments VE2 and VE3 using a gas injector (not shown). The vacuum pumps VP1 and VP2 are known per se to a person skilled in the art and can be connected to the apparatus in different ways.

[0094] The separator construction can be arranged in different ways and may comprise for example a sleeve 105 extending towards the patterning device MA, at the end of which a hole 104 extending towards the patterning device MA is provided. The sleeve 105 carrying the hole 104 may have a tapering cross section.

[0095] The apparatus also comprises a radiation beam shaping device comprising a patterning device masking blade REB for controlling the size of the projection beam PB. Figure 4 As shown, such a blade REB extends at least partially between the patterning device MA and the aperture 104 of the separator construction 103 during use.

[0096] Figure 3 Schematically shown is a mask table MT holding the patterning device MA, and blades REB-X and REB-Y, which are located near the patterning device MA for controlling the shape of the projection beam in the X-direction and the Y-direction respectively. When viewed along the Z-direction, the Y-blade REB-Y is positioned closer to the patterning device MA than the X-blade REB-X, but of course the arrangement may be the other way around, i.e. the X-blade REB-X is positioned closer to the patterning device MA than the Y-blade REB-Y. The patterning device stage metrology frame RS-MF is provided with an aperture 4 for allowing the radiation beam to reach the patterning device MA and be reflected by the patterning device MA.

[0097] The X-blade REB-X is positioned at a small distance 10a measured in the Z direction from the projection beam aperture 4. This latter distance is at most approximately 5 mm and at most approximately 2 mm.

[0098] Furthermore, the Y-blade REB-Y is positioned at a small distance 10b from the patterning device MA. This last mentioned distance is also at most about 5 mm measured in the Z direction.

[0099] The minimum distance 10c between the X-blade and the Y-blade may be about 5 mm when measured in the Z direction.

[0100] Figure 4 and 5 Schematic side and plan views of the patterning device assembly are shown in more detail, respectively. Figure 4As shown, a gas injection device comprising a gas supply conduit 121 with a respective gas outlet 120 is arranged on either side of the patterning device MA and is arranged so that a gas (particularly hydrogen, helium, nitrogen, oxygen or argon) can be injected in a direction parallel to the surface of the patterning device MA (in the direction of the arrow in the figure) and generally in the space between the patterning device MA and the blades REB-X, REB-Y. By injecting the gas close to the surface of the patterning device, and in particular into the confined space between the surface of the patterning device and the blade, the possibility of contamination from components such as the blade itself and other components is significantly reduced. It is further advantageous to provide a support structure for keeping the patterning device in a partially closed environment (at least in the vicinity of the confined space between the surface of the patterning device and the blade). In this configuration, due to the pressure generated in the partially closed environment, an even more efficient gas transport towards the projection optics compartment can be achieved.

[0101] One or more gas supply conduits are arranged to be coupled to the support structure. For example, the gas supply conduits are arranged such that they extend downwardly through the support structure MT in a vertical direction (i.e. in the z-direction) or at an inclination defining an angle with the z-direction. The outlets of the gas supply conduits are preferably oriented towards the patterning device surface, e.g. horizontally (i.e. in the XY plane). Figure 5 Specifically shown are three gas outlets 120, which are arranged equally, i.e. equidistantly, on each side of the pattern forming device. A gas supply conduit 121 is arranged to extend vertically (i.e. in the z direction) through the pattern forming device assembly, and the outlet of the gas supply conduit is oriented horizontally (i.e. in the XY plane) so that hydrogen is supplied parallel to the surface of the pattern forming device MA in the space between the pattern forming device MA and the blade REB-Y. It will be understood that other numbers of gas supply conduits and other arrangements can be provided, which achieve the same purpose of supplying gas in a direction parallel to the surface of the pattern forming device MA and between the pattern forming device and the blade. However, the gas supply conduit is formed as part of the pattern forming device platform so that the gas supply conduit moves with the pattern forming device platform even during larger movements of the pattern forming device.

[0102] For example, the gas may be injected in the X direction or the Y direction (as shown, the gas is injected in the X direction). The gas is injected in the X direction because in this case, the conduit 121 interferes less with the motion of the patterning device platform. The gas is injected between the blades closest to the patterning device (in this case, the REB-Y blade), but it may also be injected between the REB-Y blade and the REB-X blade. Generally, the gas conduit is positioned only about 10 mm from the surface of the patterning device MA.

[0103] Within the projection system PS, there are optical elements, such as mirrors, for directing and / or conditioning the EUV radiation beam. In order to provide an environment that prevents oxidation and contamination of the optical elements, it is known to supply hydrogen gas into the projection system PS. The hydrogen gas may be at least partially ionized under the influence of EUV radiation and contain hydrogen radicals. This environment is referred to herein as hydrogen plasma and may comprise only hydrogen gas, or a mixture of hydrogen gas and hydrogen radicals, or only hydrogen radicals.

[0104] Reference above Figure 1-5 Described are parts of a known lithographic apparatus for performing a lithographic process using EUV radiation.The patterning device MA used in the above-mentioned known lithographic apparatus is not covered by a pellicle.

[0105] Known pellicles for use with EUV radiation are based on polysilicon cores. These pellicles show good tolerance or resistance to operating conditions, especially plasma environments. However, a problem with these pellicles is that the transmittance of EUV radiation through these pellicles is only about 75%-85%. Another problem is that the pellicles have large false reflections of DUV radiation. Resists are sensitive to DUV radiation and therefore require additional spectral purity diaphragms to suppress the effects of DUV reflections. The use of such known pellicles therefore reduces the total transmittance of the EUV radiation beam by about 50%.

[0106] Another problem is the use of DUV radiation for patterning device inspection. When the polysilicon pellicle is in place, the patterning device cannot be inspected due to the poor transmission of DUV radiation through the pellicle. To make it possible to inspect the patterning device, the pellicle must therefore be easily removable, and this complicates the installation of the pellicle and compromises other embodiments.

[0107] The above problems with polysilicon-based pellicles can be avoided by using a carbon-based pellicle instead. Carbon-based pellicles have high EUV transmittance (potentially over 95%), low DUV reflectivity, and the transmittance of DUV radiation through the pellicle is sufficient to perform patterning device inspection when the pellicle is in place. Some of the advantages of carbon-based pellicles are described in "CNTs in the context of EUV pellicle history," E. Gallagher et al., Proc. SPIE, 2018.

[0108] The problem with using carbon-based pellicles is that they cannot withstand the operating conditions. In particular, the carbon-based pellicles are severely degraded by the extremely reducing hydrogen plasma environment. The resistance or tolerance of the carbon-based pellicles to the operating conditions can be increased by coating the pellicles with molybdenum or zirconium. However, when such coatings are applied, the transmittance through the pellicle is reduced and EUV scattering and reflection increases to the extent that the imaging properties and transmittance of the radiation beam are significantly deteriorated.

[0109] Embodiments provide a lithographic apparatus for performing a lithographic process using EUV radiation. The patterning device used in the lithographic apparatus according to embodiments is covered by a pellicle.

[0110] The pellicle advantageously protects the patterning device by shielding the patterning device from any particles and air currents.

[0111] The pellicle is preferably thin and substantially transparent to the radiation beam so that the pellicle does not substantially reduce the power of the radiation beam. The pellicle should also be able to withstand the operating conditions, i.e., the power of the radiation beam and the use of a plasma environment, without rapid degradation.

[0112] Embodiments address the above-mentioned problems of using a pellicle in an EUV lithographic apparatus by providing at least a first region and a second region in the path of the radiation beam, each region having different properties.

[0113] The first region is essentially only the local environment of the pellicle. The first region at least adjoins the surface of the pellicle and preferably includes the pellicle. In the first region, a gas environment is provided, which is suitable for using a carbon-based pellicle without a molybdenum or zirconium coating of the pellicle.

[0114] The second region is within the projection system PS but excludes the local environment of the pellicle.The second region includes optical elements of the projection system PS, wherein a plasma environment, such as hydrogen plasma, is provided, thereby preventing oxidation and contamination of the mirrors.

[0115] According to an embodiment, a carbon-based membrane is used. The carbon-based membrane has high transmittance, high heat capacity, and is not degraded by the gas environment set in the first region. The carbon-based membrane can be constructed in any of a variety of known ways and from a range of carbon-based materials. For example, it can be formed from any of carbon nanotubes, graphene, or diamond.

[0116] Advantageously, the pellicle according to an embodiment does not require a molybdenum or zirconium coating. The overall transmittance of the EUV radiation beam is thus improved over that achieved when using a polysilicon based pellicle or a carbon based pellicle coated with molybdenum or zirconium.

[0117] Figure 6 It is shown how the first area and the second area may be arranged according to an embodiment.

[0118] Figure 6 , there is shown a pattern forming device 601, a surface film 602 covering the pattern forming device 601, one or more outlets 603 of a first group, one or more outlets 605 of a second group, one or more inlets 604 of a first group, one or more inlets 606 of a second group, a first fluid supplier 607 (such as a container or a connector) fluidically connected to the one or more outlets 603 of the first group, and a second fluid supplier 607 (such as a container or a connector) fluidically connected to the one or more outlets 605 of the second group.

[0119] Figure 6 A number of other components not shown may be included. In particular, the optical elements in the second region are not shown. A physical separator may be present between the pattern forming device 601 portion and the optical elements. A blade (such as Figure 3 and Figure 4 blade shown in ), and other parts. Figure 6 Not fully shown in the figure, there is also a patterning device support holding the patterning device 601.

[0120] The first group of one or more outlets 603 may be a plurality of outlets arranged along the side of the membrane 602, such as along Figure 5 As shown in the side of the pattern forming device 601.

[0121] The gas is output from the first set of one or more outlets 603 to the local environment of the pellicle 602. The gas output from the first set of one or more outlets 603 includes an inert and / or chemically neutral gas that does not degrade the carbon-based pellicle 602. For example, the gas can be any of helium, neon, argon, or nitrogen. Advantageously, the carbon-based pellicle 602 is able to withstand the conditions in the local environment of the pellicle 602.

[0122] The first set of one or more inlets 604 is preferably also disposed proximate to the diaphragm 602 for removing gas from the first region, i.e., the local environment of the diaphragm 602. The first set of one or more outlets 603 is preferably disposed on the opposite side of the diaphragm 602 from the first set of one or more inlets. The first region thus includes a cross flow of gas across the diaphragm 602.

[0123] The second set of one or more outlets outputs a gas and / or a plasma (such as a hydrogen plasma as is known for use with EUV radiation in lithographic apparatus) into the second region.

[0124] A second set of one or more inlets 606 is preferably also arranged for removing gas and / or plasma from the projection system PS. The second set of one or more gas inlets is preferably arranged on the opposite side of the projection system PS to the second set of one or more inlets so that there is a cross-flow of gas and / or plasma through the second region.

[0125] Although Figure 6 Not shown, but the second region comprises optical elements of the projection system PS, and the one or more outlets and inlets of the second group are arranged between the one or more outlets and inlets of the first group and the optical elements of the projection system PS.

[0126] Although Figure 6 Not shown, the lithographic apparatus also comprises a control system, and one or more of any one of conduits, valves and pumps for providing control over the flow of fluid into the first region and the second region, and preferably also the flow out of the first region and the second region.

[0127] The first region and the second region are not separated by a physical barrier that prevents fluid in the second region from flowing into the first region and reaching the pellicle 602. The boundary between the first region and the second region is therefore roughly defined as the location where the concentration of fluid from the second region is large enough to cause substantial damage to the carbon-based pellicle. The boundary depends on how the fluid flow is controlled by the control system and the environment of the pellicle and in the projection system.

[0128] However, the positioning of the first set of one or more outlets and inlets proximate to the pellicle 602, the directing of the gas output from the one or more outlets across the pellicle 602, and the positioning of the second set of one or more outlets and inlets further from the pellicle 602 than the first set of one or more outlets and inlets, all result in the local environment of the pellicle 602 being substantially composed of gas from the first set of one or more outlets 603, so that the carbon-based pellicle 602 in or adjacent to the first region is not substantially degraded. The first region may be composed of at least 80% to 90% of the gas from the first set of one or more outlets 603, and this is sufficient to prevent the carbon-based pellicle 602 from being substantially degraded by fluid from the second region.

[0129] By controlling the rate at which fluid flows out of one or more first outlets and / or one or more second outlets, and / or by controlling the rate at which fluid flows out of one or more first inlets and / or second inlets, the control system can control the width of the first region in the direction of the radiation beam.

[0130] The first region may cover the entire surface of the pellicle 602, and preferably covers the entire pellicle 602. The first region should also be thin in the direction of the radiation beam passing through the pellicle 602, so that there is only a short path distance for the radiation beam to pass through the first region. The width of the first region in the direction of the radiation beam should be large enough to ensure that the amount of fluid (i.e., gas and / or plasma) from the second region that is likely to reach the pellicle 602 is not large enough to substantially damage the pellicle 602. However, the first region is also preferably controlled by the control system to be substantially no wider than the width necessary to achieve this, so as to minimize the distance that the radiation beam travels through the first region. Any degrading effect that the gas in the first region has on the radiation beam (such as EUV radiation being absorbed) is therefore minimized.

[0131] The amount of EUV radiation absorbed by the gas in the first region is relatively small. Due to the high transmittance of the carbon-based pellicle 602 and the relatively small amount of absorption in the first region, an overall performance gain is provided over known technologies utilizing polysilicon-based pellicles or carbon-based pellicles coated with molybdenum or zirconium.

[0132] In a lithographic apparatus according to an embodiment, an EUV radiation beam that has been patterned by the pattern forming device 601 travels from the surface of the pattern forming device 601 and passes through a carbon-based pellicle 602 having a high EUV radiation transmittance. The pellicle 602 is adjoined by and / or included by a first region that provides a gas environment that does not degrade the pellicle 602. The radiation beam then travels away from the first region and travels to a second region that includes an optical element of a projection system PS. The second region provides a gas and / or plasma environment, such as a hydrogen plasma, as required by the optical element. The radiation beam then travels away from the projection system PS and travels onto a substrate.

[0133] Figure 7 is a flow chart of a process according to an embodiment.

[0134] In step 701, the process starts.

[0135] In step 703, the radiation beam is adjusted.

[0136] In step 705, a patterning device (601) imparts a pattern to the radiation beam in its cross-section to form a patterned radiation beam, wherein a pellicle (602) covers a surface of the patterning device.

[0137] In step 707, a projection system projects the patterned radiation beam onto a target portion of the substrate, wherein the projection system includes one or more optical elements.

[0138] In step 709, a first set of one or more outlets (603) output a first fluid into a first region, wherein the first region is adjacent to and / or includes the pellicle (602).

[0139] In step 711, one or more outlets (605) of the second group output a second fluid into a second region including one or more optical elements of the projection system; wherein the second fluid is different from the first fluid; and optionally, wherein the pattern forming device (601), the pellicle (602), the one or more outlets of the first group, the one or more outlets of the second group and the substrate are arranged so that the patterned radiation beam travels from the pattern forming device (601), then passes through the pellicle (602) adjacent to and / or included by the first region, then passes through the second region and then onto the substrate held by the substrate stage.

[0140] In step 713, the process ends.

[0141] Various embodiments also include many modifications to the above-described techniques.

[0142] In particular, it is not necessary to provide one or more inlets of the first group and / or one or more inlets of the second group. In addition, the one or more inlets of the first group described above may actually be one or more outlets of a group of the same gas output from the one or more outlets 603 of the first group. Thus, the arrangement of the outlets for the gas of the first region will be substantially as follows: Figure 5 Advantageously, this arrangement of the outlets forces the gas flow in the first region away from the pellicle 602 and thereby reduces the likelihood of gas and / or plasma from the second region reaching the pellicle 602 .

[0143] As mentioned above Figure 1 As shown in the described alternative, the lithographic apparatus may be used with an alternative type of patterning device 601 that imparts a pattern on a radiation beam when the radiation beam passes through the patterning device 601 rather than being reflected from the patterning device 601. The patterning device 601 will still be covered by the carbon-based pellicle 602, which is possible due to the arrangement of the first region as described above.

[0144] Preferably, the gas output from the first set of one or more outlets 603 is neon, argon or nitrogen. These gases include relatively heavy atoms / molecules, and due to their higher inertia than helium, it is easier to maintain the first region when one of these gases is used.

[0145] Arranging the first region to have a different composition than the second region according to an embodiment provides further advantages over those described above. These advantages may include improved particle protection of the patterning device 601 and / or the pellicle 602 due to the use of a relatively heavy gas in the first region, and reduced shear forces at the walls. Tolerance to electrical breakdown may also be increased, which may be necessary due to potentially high electrostatic fields around the patterning device support. In this case, a suitable gas for use in the first region would be nitrogen.

[0146] Embodiments also include the use of known polysilicon pellicles, wherein the first region comprises an inert and / or chemically neutral gas as described above. Such a first region will reduce the generation of hydrogen sulfide at the pellicle, which may lead to deposition in the projection system PS.

[0147] Embodiments also include lithographic apparatus in which the gas output through at least the first set of one or more outlets 603 can be changed. For example, if a carbon-based pellicle 602 is being used, the gas output should be an inert and / or chemically neutral gas as described above. However, if a polysilicon-based pellicle is used, the gas output from the first set of one or more outlets may be a hydrogen plasma (or there may be no gas output). The gas output is therefore selected depending on the type of pellicle being used. The time required to change the pellicle or change the patterning device 601 together with the pellicle is about 20 seconds to 30 seconds.

[0148] Embodiments may generally be used to provide an environment for the membrane that protects the membrane from all other environments in the system. In particular, the first region may not only be a local environment for the membrane. For example, when targeting Figure 2 When the pellicle of the patterning device in the system shown in FIG. 8 provides the first region, the first region may include all of region VE1 and protect the pellicle from the gas / plasma in regions VE2 and VE3 .

[0149] Figure 8 and Fig. 9 A schematic side view and a plan view of a substrate table WT configured to hold the substrate W in a substrate region 223 are shown, respectively. According to a third aspect of the invention, a gas supply conduit 221 feeding a third set of one or more gas outlets 220 is provided on either side of the substrate region 223. The third set of one or more outlets 220 are arranged so that gas can be injected in a direction parallel to the surface of the substrate W (in the direction of the arrow in the figure). The outlets 220 output gas into a third region 224, which in this embodiment is adjacent to the substrate region 223. By injecting gas close to the substrate, the substrate is protected from the influence of the second region 225, which prevents the substrate from being degraded, such as damaged, etched or contaminated, by the fluid present in the second region 225.

[0150] Fig. 9 In particular, three gas outlets 220 and associated gas supply conduits are shown that are equidistantly disposed on each lateral side of the substrate area 223. It will be appreciated that other numbers of gas outlets and / or gas supply conduits and other arrangements of gas outlets and / or gas supply conduits that achieve the same goal of supplying gas may be provided. Preferably, the gas is supplied in a direction parallel to the surface of the substrate.

[0151] Although Figure 8 and Fig. 9 Although not shown in the drawings, the substrate may be covered by a membrane configured to cover a surface of the substrate. The third region may adjoin and / or include the substrate.

[0152] A schematic example of a substrate W having one surface covered by a membrane 502 is shown in Fig.10 Shown in. Fig.10 Also shown are one or more outlets 503 of a third group for outputting a third fluid to a third region; one or more inlets 504 of a third group for discharging fluid from the third region; a third fluid supplier 507, such as a connector or a container, fluidically connected to the one or more outlets 503 of the third group; one or more outlets 505 of a second group for outputting the second fluid to the second region; one or more inlets 506 of a second group for discharging fluid from the second region; and a second fluid supplier 508, such as a connector or a container, fluidly connected to the one or more outlets 505 of the second group.

[0153] Fig.10 A number of other components not shown may be included. In particular, the optical elements in the second region are not shown. There may be a physical separator between the substrate W and the optical elements. Fig.10 Not shown in the figure, there is also a substrate support holding the substrate W and a membrane support holding the membrane 502.

[0154] The one or more outlets 503 of the third group may be a plurality of outlets arranged along the side of the substrate W, such as along Fig. 9 The side of the substrate W is shown.

[0155] Gas is output from the one or more outlets 503 of the third group to the local environment of the membrane 502. The gas output from the one or more outlets 503 of the third group includes an inert and / or chemically neutral gas that does not degrade the substrate W and / or the membrane 502. For example, the gas may be any one of helium, neon, argon or nitrogen. Advantageously, the membrane 502 is able to withstand the conditions in the local environment of the membrane 502.

[0156] The third set of one or more inlets 504 is also preferably provided proximate to the diaphragm 502 for removing gas in the third region, i.e., the local environment of the diaphragm 502. The third set of one or more outlets 503 is preferably provided on the opposite side of the diaphragm 502 from the third set of one or more inlets 504. The third region thus comprises a cross-flow of gas across the diaphragm 502.

[0157] The second set of one or more outlets outputs gas and / or plasma, such as hydrogen plasma as is known for use with EUV radiation in lithographic apparatus, into the second region.

[0158] The second set of one or more inlets 506 are preferably also arranged for removing gas and / or plasma in the projection system PS. The second set of one or more gas outlets 505 are preferably arranged on the opposite side of the projection system PS to the second set of one or more inlets 506 so that there is a cross-flow of gas and / or plasma through the second region.

[0159] Although Fig.10 Not shown, but the second region comprises optical elements of the projection system PS, and the one or more outlets and inlets of the second group are arranged between the one or more outlets and inlets of the third group and the optical elements of the projection system PS.

[0160] Although Fig.10 Not shown, the lithographic apparatus also includes a control system, and one or more of any of conduits, valves and pumps for providing control over the flow of fluid into the second and third regions, and preferably out of both the second and third regions.

[0161] The third region and the second region are not separated by a physical barrier that prevents fluid in the second region from flowing into the third region and reaching the membrane 502 or substrate W. The boundary between the third region and the second region is therefore roughly defined as the point where the concentration of fluid from the second region is large enough to cause substantial damage to the substrate or membrane. The boundary depends on how the control system controls the flow of fluids, as well as the environment of the pellicle and in the projection system.

[0162] However, the positioning of the one or more outlets and inlets of the third group in close proximity to the membrane 502 and / or substrate W, the directing of gas output from one or more outlets across the membrane 502, and the positioning of the one or more outlets and inlets of the second group further away from the membrane 502 and / or substrate W than the one or more outlets and inlets of the third group, all result in the local environment of the membrane 502 and / or substrate W being substantially composed of gas from the one or more outlets 503 of the third group, so that the membrane 502 (or substrate W) in or adjacent to the third region is not substantially degraded. The third region may be composed of at least 80% to 90% of gas from the one or more outlets 503 of the third group, and this is sufficient to prevent the membrane 502 and / or substrate W from being substantially degraded by fluid from the second region.

[0163] By controlling the rate at which fluid flows out of one or more third outlets and / or one or more second outlets, and / or by controlling the rate at which fluid flows out of one or more third inlets and / or second inlets, the control system can control the width of the third region in the direction of the radiation beam.

[0164] The third region may cover the entire surface of the membrane 502 and / or substrate W, and preferably covers the entire membrane 502 and / or substrate W. The third region should also be thin in the direction of the radiation beam passing through the membrane 502, so that there is only a short path distance of the radiation beam passing through the third region. The width of the third region in the direction of the radiation beam should be large enough to ensure that the amount of fluid (i.e. gas and / or plasma) from the second region that is likely to reach the membrane 502 and / or substrate W is not large enough to substantially damage the membrane 502 and / or substrate W. However, the third region is preferably also controlled by the control system to be substantially no wider than necessary to achieve this, so as to minimize the distance traveled by the radiation beam through the third region. Any deteriorating effect that the gas in the third region has on the radiation beam (such as EUV radiation being absorbed) is thereby minimized.

[0165] The amount of EUV radiation absorbed by the gas in the third region is relatively small. Due to the high transmittance of the membrane 502 and the relatively small amount of absorption in the third region, an overall performance gain over known techniques is provided.

[0166] In a lithographic apparatus according to an embodiment, an EUV radiation beam that has been patterned by the pattern forming device travels from the surface of the pattern forming device and passes through a pellicle having a high EUV radiation transmittance. The radiation beam then travels from the pellicle to a second region of the optical element including the projection system PS. The second region provides a gas and / or plasma environment as required by the optical element, such as a hydrogen plasma. The radiation beam then travels away from the projection system PS and the second region, travels into the third region, passes through an optionally present diaphragm, and reaches the substrate.

[0167] Although specific reference may be made herein to embodiments of the invention in the context of a lithographic apparatus, embodiments of the invention may be used in other apparatus. Embodiments of the invention may form part of a mask inspection apparatus, a metrology apparatus, or any apparatus for measuring or processing an object such as a wafer (or other substrate) or a mask (or other patterning device 601). These apparatuses may generally be referred to as lithographic tools. Such lithographic tools may use vacuum conditions or ambient (non-vacuum) conditions.

[0168] The term "EUV radiation" may be taken to encompass electromagnetic radiation having a wavelength in the range of 4 to 20 nm, for example in the range of 13 nm to 14 nm. EUV radiation may have a wavelength less than 10 nm, for example in the range of 4 to 10 nm, such as 6.7 nm or 6.8 nm.

[0169] Although specific reference may be made herein to the use of lithographic equipment in IC manufacturing, it should be understood that the lithographic equipment described herein may have other applications. Possible other applications include manufacturing integrated optical systems, guidance and detection patterns for magnetic domain memory, flat panel displays, liquid crystal displays (LCDs), thin film magnetic heads, etc.

[0170] Where the terms "first", "second" and "third" are used in this application, this is used to distinguish one from another rather than to show anything about numbering. For example, discussing the "second region" and the "third region" does not mean that there is also a "first region".

[0171] Embodiments of the first, second, third and fourth aspects of the present invention may be described according to one or more of the following aspects:

[0172] 1) A lithography apparatus, comprising:

[0173] an irradiation system configured to condition the radiation beam;

[0174] a patterning device (601) configured to impart a pattern to the radiation beam in a cross-section of the radiation beam to form a patterned radiation beam;

[0175] A surface film (602) configured to cover the surface of the pattern forming device (601);

[0176] a substrate stage configured to hold a substrate;

[0177] a projection system configured to project a patterned radiation beam onto a target portion of a substrate while the substrate is held by the substrate table, wherein the projection system comprises one or more optical elements;

[0178] a first set of one or more outlets (603) for outputting a first fluid into a first region, wherein the first region is adjacent to and / or includes the pellicle (602); and

[0179] a second set of one or more outlets (605) configured to output a second fluid into a second region, the second region comprising one or more optical elements of the projection system; and

[0180] The second fluid is different from the first fluid.

[0181] 2) A lithographic apparatus according to aspect 1, wherein the pattern forming device (601), the pellicle (602), the one or more outlets (603) of the first group, the one or more outlets (605) of the second group and the substrate table are arranged such that, in use, a patterned radiation beam travels from the pattern forming device (601), then passes through the pellicle (602) adjacent to and / or included by the first region, then passes through the second region, and then reaches the substrate held by the substrate table.

[0182] 3) A lithographic device according to any of the preceding aspects, wherein the one or more outlets (603) of the first group are configured to provide a first gas environment in the first region, and the first gas environment protects the surface film (602) from the influence of the second region or prevents the fluid in the second region from reaching the surface film (602).

[0183] 4) The lithographic apparatus according to any preceding aspect, wherein the first fluid is a gas that is inert and / or chemically neutral to the pellicle (602).

[0184] 5) The lithographic apparatus according to any preceding aspect, wherein the first fluid comprises one or more of helium, neon, argon or nitrogen.

[0185] 6) A lithographic apparatus according to any preceding aspect, wherein the second fluid comprises a gas and / or plasma that degrades the pellicle.

[0186] 7) A lithographic apparatus according to any preceding aspect, wherein the second fluid comprises a gas and / or plasma, such as a hydrogen plasma, for preventing oxidation and contamination of one or more optical elements of the projection system.

[0187] 8) The lithographic apparatus according to clause 7, wherein the second fluid comprises hydrogen radicals.

[0188] 9) The lithographic apparatus according to any preceding aspect, further comprising a patterning device support arranged to support the patterning device (601), wherein the pellicle (602) is coupled to the patterning device support.

[0189] 10) A lithographic apparatus according to any preceding aspect, wherein one or more of the one or more outlets (605) of the second group are arranged between the one or more outlets (603) of the first group and one or more optical elements of the projection system.

[0190] 11) The lithographic apparatus according to any preceding aspect, further comprising a first set of one or more inlets (604), the first set of one or more inlets being arranged in the first region for removing fluid from the first region.

[0191] 12) A lithographic device according to aspect 11, wherein the one or more inlets (604) of the first group are arranged on the side of the diaphragm (602) opposite to the one or more outlets (603) of the first group, so that in use, there is a cross-flow of the first fluid across the diaphragm (602).

[0192] 13) The lithographic apparatus according to any preceding aspect, further comprising a second set of one or more inlets (606), the second set of one or more inlets (606) being arranged in the second region for removing fluid from the second region.

[0193] 14) A lithographic apparatus according to clause 13, wherein the one or more inlets (606) of the second group are arranged on a side of the projection system opposite to the one or more outlets (605) of the second group, so that in use there is a cross-flow of the second fluid across the projection system.

[0194] 15) The lithographic apparatus according to any preceding aspect, wherein the pellicle (602) is carbon-based.

[0195] 16) A lithographic apparatus according to clause 15, wherein the first fluid comprises a carbon-containing gas.

[0196] 17) A lithographic apparatus according to clause 15 or 16, wherein the pellicle (602) comprises one or more of carbon nanotubes and diamond.

[0197] 18) The lithographic apparatus according to any preceding aspect, wherein the illumination system is configured to condition an extreme ultraviolet (EUV) radiation beam.

[0198] 19) A lithographic apparatus according to any preceding aspect, wherein one or more of the one or more optical elements are mirrors.

[0199] 20) The lithographic apparatus according to any preceding aspect further comprises a control system configured to select the first fluid to be output from the one or more outlets (603) of the first group depending on the type of the pellicle being used.

[0200] 21) The lithography device according to any of the preceding aspects further includes a first fluid supplier containing the first fluid and a second fluid supplier containing the second fluid, wherein the first fluid supplier (607) is fluidically connected to one or more outlets (603) of the first group, and the second fluid supplier (608) is fluidically connected to one or more outlets (605) of the second group.

[0201] 22) A method comprising:

[0202] adjusting (703) the radiation beam;

[0203] imparting (705) a pattern in a cross-section of the radiation beam to the radiation beam using a patterning device (601) to form a patterned radiation beam, wherein the pellicle (602) covers a surface of the patterning device;

[0204] projecting (707) the patterned radiation beam onto a target portion of a substrate by a projection system, wherein the projection system comprises one or more optical elements;

[0205] Outputting (709) a first fluid into a first region from a first set of one or more outlets (603), wherein the first region is adjacent to and / or includes the pellicle (602); and

[0206] Outputting (711) a second fluid from a second set of one or more outlets (605) to a second region, the second region comprising one or more optical elements of the projection system;

[0207] The second fluid is different from the first fluid.

[0208] 23) A method according to aspect 22, wherein the pattern forming device (601), the diaphragm (602), one or more outlets of the first group, one or more outlets of the second group and the substrate are arranged so that the patterned radiation beam travels from the pattern forming device (601), then passes through the diaphragm (602) adjacent to and / or included by the first area, then passes through the second area, and then reaches the substrate held by the substrate table.

[0209] 24) A method according to clause 22 or 23, wherein the method is performed by a lithography device according to any one of clauses 1-21.

[0210] 25) The method according to any of aspects 22-24 further comprises selecting the first fluid output by the one or more outlets (603) of the first group depending on the type of diaphragm being used.

[0211] 26) A method according to any one of aspects 22-25, wherein the output of the first fluid into the first region results in the generation of a first gas environment in the first region that protects the surface film (602) from the influence of the second region.

[0212] 27) A method according to any one of aspects 22-25, wherein the output of the first fluid into the first region causes a first gas environment to be generated in the first region that prevents the fluid in the second region from reaching the surface film (602).

[0213] 28) A method according to any one of aspects 22-27, wherein the first fluid is a gas that is inert and / or chemically neutral with respect to the pellicle (602).

[0214] 29) A method according to any one of aspects 22-28, wherein the first fluid comprises one or more of helium, neon, argon or nitrogen.

[0215] 30) A method according to any one of aspects 22-29, wherein the second fluid comprises a gas and / or plasma that degrades the surface film.

[0216] 31) A method according to any of aspects 22-30, wherein the second fluid comprises a gas and / or plasma, such as a hydrogen plasma, for preventing oxidation and contamination of one or more optical elements of the projection system.

[0217] 32) A method according to aspect 31, wherein the second fluid comprises hydrogen radicals.

[0218] 33) A method according to any one of aspects 22-32, wherein the surface film (602) is carbon-based and wherein the first fluid comprises a carbon-containing gas.

[0219] 34) A lithography apparatus comprising:

[0220] an irradiation system configured to condition the radiation beam;

[0221] a patterning device configured to impart a pattern in a cross-section of the radiation beam to the radiation beam to form a patterned radiation beam;

[0222] a substrate table (WT) configured to hold a substrate (W) in a substrate region (223);

[0223] a projection system configured to project the patterned radiation beam onto a target portion of a substrate (W) while the substrate (W) is held by the substrate table (WT), wherein the projection system comprises one or more optical elements;

[0224] a second set of one or more outlets (505) configured to output a second fluid to a second region (225) comprising one or more optical elements of the projection system; and

[0225] a third set of one or more outlets (220, 503) for outputting a third fluid to a third region (224), wherein the third region is adjacent to and / or includes the substrate region (223); and

[0226] The second fluid is different from the third fluid.

[0227] 35) A lithographic apparatus according to aspect 34, wherein the one or more outlets (220, 503) of the third group are configured to provide a third gas environment in the third region (224), the third gas environment protecting the substrate (W) from the influence of the second region (225).

[0228] 36) A lithographic device according to aspect 34 or 35, wherein the substrate region (223) includes a diaphragm (502), which is configured to cover the surface of the substrate (W), and wherein the third region (224) is adjacent to and / or includes the diaphragm (502).

[0229] 37) A lithographic apparatus according to aspect 36, wherein the one or more outlets (220, 503) of the third group are configured to provide a third gas environment in the third region (224), the third gas environment protecting the diaphragm (W) from the influence of the second region (225).

[0230] 38) A lithographic device according to any one of Aspects 34-37, wherein the pattern forming device (601), the projection system, one or more outlets (505) of the second group, one or more outlets (220, 503) of the third group and the substrate table (WT) are arranged so that, in use, a patterned radiation beam travels from the pattern forming device, passes through the projection system including the second region (225), passes through the third region (224), and then reaches a substrate (W) held by the substrate table (WT).

[0231] 39) A lithographic apparatus according to any one of clauses 34 to 38, wherein the third fluid is a gas that is inert and / or chemically neutral to the substrate (W).

[0232] 40) A lithographic apparatus according to any one of clauses 34 to 39, wherein the third fluid comprises one or more of helium, neon, argon or nitrogen.

[0233] 41) A lithographic apparatus according to any one of clauses 34-40, wherein the second fluid comprises a gas and / or plasma that degrades the substrate (W).

[0234] 42) A lithographic apparatus according to any of clauses 34 to 41, wherein the second fluid comprises a gas and / or plasma, such as a hydrogen plasma, for preventing oxidation and contamination of one or more optical elements of the projection system.

[0235] 43) A lithographic apparatus according to clause 42, wherein the second fluid comprises a hydrogen radical.

[0236] 44) The lithographic apparatus according to any one of aspects 34-43 further comprises a third group of one or more inlets (504), wherein the third group of one or more inlets (504) are arranged in the third region (224) for removing fluid from the third region (224).

[0237] 45) A lithographic device according to aspect 44, wherein the one or more inlets (504) of the third group are arranged on the side of the substrate (W) opposite to the one or more outlets (220, 503) of the third group, so that in use, there is a cross-flow of the third fluid across the substrate (W).

[0238] 46) The lithographic apparatus according to any preceding aspect further comprises a second set of one or more inlets (506), the second set of one or more inlets (506) being arranged in the second region (225) for removing fluid from the second region (225).

[0239] 47) A lithographic apparatus according to aspect 46, wherein the one or more inlets (506) of the second group are arranged on a side of the projection system opposite to the one or more outlets (505) of the second group, so that in use, there is a cross-flow of the second fluid across the projection system.

[0240] 48) A lithographic apparatus according to any one of clauses 34-47, wherein the illumination system is configured to condition an extreme ultraviolet (EUV) radiation beam.

[0241] 49) A lithographic apparatus according to any of clauses 34 to 48, wherein one or more of the one or more optical elements is a mirror.

[0242] 50) The lithographic apparatus according to any one of aspects 34 to 49 further comprises a control system configured to select a third fluid to be output from one or more outlets (220, 503) of the third group depending on the type of substrate or membrane being used.

[0243] 51) The lithography device according to any of the preceding aspects further includes a second fluid supplier (508) containing the second fluid and a third fluid supplier (507) containing the third fluid, wherein the second fluid supplier (508) is fluidically connected to one or more outlets (505) of the second group, and the third fluid supplier (508) is fluidically connected to one or more outlets (503) of the third group.

[0244] 52) A method comprising:

[0245] regulating the radiation beam;

[0246] imparting, by a patterning device, a pattern in a cross-section of the radiation beam to the radiation beam to form a patterned radiation beam;

[0247] projecting the patterned radiation beam onto a target portion of a substrate held in a substrate region by a projection system, wherein the projection system includes one or more optical elements;

[0248] outputting a second fluid from a second set of one or more outlets into a second region including one or more optical elements of the projection system; and

[0249] outputting a third fluid into a third region from one or more outlets of a third group, wherein the third region is adjacent to and / or includes the substrate region; and

[0250] The second fluid is different from the third fluid.

[0251] 53) A method according to aspect 52, wherein a third fluid output into the third region provides a third gas environment in the third region, the third gas environment protecting the substrate from the second region.

[0252] 54) A method according to aspect 52 or 53, wherein the substrate region includes a membrane, the membrane is configured to cover the surface of the substrate, and wherein the third region is adjacent to and / or includes the membrane.

[0253] 55) A method according to aspect 54, wherein the third fluid output into the third region provides a third gas environment in the third region, the third gas environment protecting the diaphragm from the influence of the second region.

[0254] 56) A method according to any one of Aspects 52-55, wherein the pattern forming device, the diaphragm, one or more outlets of the second group, one or more outlets of the third group, and the substrate are arranged so that the patterned radiation beam travels from the pattern forming device, passes through the second region, passes through the third region, and then reaches the substrate held by the substrate table.

[0255] 57) A method according to any one of aspects 52-56, wherein the method is performed by a lithography device according to any one of aspects 34-51.

[0256] 58) The method of any one of aspects 52-57 further comprises selecting the third fluid output by one or more outlets of the third set depending on the type of substrate or membrane being used.

[0257] 59) A method according to any one of aspects 52-58, wherein the third fluid is a gas that is inert and / or chemically neutral to the substrate.

[0258] 60) A method according to any of Aspects 52-59, wherein the third fluid comprises one or more of helium, neon, argon or nitrogen.

[0259] 61) A method according to any of Aspects 52-60, wherein the second fluid comprises a gas and / or plasma that degrades the substrate.

[0260] 62) A method according to any of aspects 52-61, wherein the second fluid comprises a gas and / or plasma, such as a hydrogen plasma, for preventing oxidation and contamination of one or more optical elements of the projection system.

[0261] 63) A method according to aspect 62, wherein the second fluid comprises hydrogen radicals.

[0262] Although specific embodiments of the present invention have been described above, it will be appreciated that the present invention may be practiced in a manner different from that described above. The above description is intended to be illustrative rather than restrictive. Therefore, it will be appreciated by those skilled in the art that modifications may be made to the described invention without departing from the scope of the claims set forth below.

Claims

1. A lithographic apparatus, comprising: an irradiation system configured to condition the radiation beam; a patterning device (601) configured to impart a pattern to the radiation beam in a cross-section of the radiation beam to form a patterned radiation beam; A surface film (602) configured to cover the surface of the pattern forming device (601); a substrate stage configured to hold a substrate; a projection system configured to project a patterned radiation beam onto a target portion of a substrate while the substrate is held by the substrate table, wherein the projection system comprises one or more optical elements; a first set of one or more outlets (603) for outputting a first fluid into a first region, wherein the first region is adjacent to and / or includes the pellicle (602); and a second set of one or more outlets (605) configured to output a second fluid into a second region, the second region including the one or more optical elements of the projection system; as well as wherein the second fluid is different from the first fluid; wherein the first fluid is a gas that is inert and / or chemically neutral to the pellicle (602); and The second fluid includes a gas and / or a plasma that degrades the surface film.

2. The lithographic apparatus according to claim 1, wherein: The pattern forming device (601), the diaphragm (602), one or more outlets (603) of the first group, one or more outlets (605) of the second group and the substrate table are arranged so that, in use, a patterned radiation beam travels from the pattern forming device (601), then passes through the diaphragm (602) adjacent to and / or included by the first area, then passes through the second area, and then reaches the substrate held by the substrate table.

3. A lithographic device according to any preceding claim, wherein the one or more outlets (603) of the first group are configured to provide a first gas environment in the first region, the first gas environment protecting the surface film (602) from the influence of the second region. 4 . The lithographic apparatus of claim 1 , wherein the first fluid comprises one or more of helium, neon, argon or nitrogen.

5. The lithographic apparatus of claim 1, wherein the second fluid comprises a gas and / or a plasma for preventing oxidation and contamination of the one or more optical elements of the projection system. The lithographic apparatus of claim 5 , wherein the plasma is a hydrogen plasma.

7. The lithographic apparatus of claim 5, wherein the second fluid comprises a hydrogen radical.

8. The lithographic apparatus according to claim 1, further comprising a patterning device support arranged to support the patterning device (601), wherein the pellicle (602) is coupled to the patterning device support.

9. The lithographic apparatus of claim 1, wherein one or more of the second group of one or more outlets (605) are arranged between the first group of one or more outlets (603) and the one or more optical elements of the projection system.

10. The lithographic apparatus of claim 1, further comprising a first set of one or more inlets (604), the first set of one or more inlets being arranged in the first region for removing fluid from the first region.

11. A lithographic device according to claim 10, wherein the one or more inlets (604) of the first group are arranged on the side of the diaphragm (602) opposite to the one or more outlets (603) of the first group, so that in use, there is a cross-flow of the first fluid across the diaphragm (602).

12. The lithographic apparatus of claim 1, further comprising a second set of one or more inlets (606), the second set of one or more inlets (606) being arranged in the second region for removing fluid from the second region.

13. A lithographic apparatus according to claim 12, wherein the second set of one or more inlets (606) are arranged on a side of the projection system opposite to the second set of one or more outlets (605) so that in use there is a cross-flow of the second fluid across the projection system.

14. The lithographic apparatus of claim 1, wherein the pellicle (602) is carbon-based.

15. The lithographic apparatus of claim 14, wherein the first fluid comprises a carbon-containing gas.

16. The lithographic apparatus of claim 14 or 15, wherein the pellicle (602) comprises one or more of carbon nanotubes and diamond.

17. The lithographic apparatus of claim 1, wherein the illumination system is configured to condition an extreme ultraviolet (EUV) radiation beam.

18. The lithographic apparatus of claim 1, wherein one or more of the one or more optical elements are mirrors.

19. The lithographic apparatus of claim 1, further comprising a control system configured to select the first fluid to be output from the first set of one or more outlets (603) depending on the type of pellicle being used.

20. The lithography device according to claim 1 further includes a first fluid supplier for containing the first fluid and a second fluid supplier for containing the second fluid, wherein the first fluid supplier (607) is fluidically connected to one or more outlets (603) of the first group, and the second fluid supplier (608) is fluidically connected to one or more outlets (605) of the second group.

21. A method comprising: adjusting (703) the radiation beam; imparting (705) a pattern in a cross-section of the radiation beam to the radiation beam using a patterning device (601) to form a patterned radiation beam, wherein the pellicle (602) covers a surface of the patterning device; projecting (707) the patterned radiation beam onto a target portion of a substrate by a projection system, wherein the projection system comprises one or more optical elements; outputting (709) a first fluid from a first set of one or more outlets (603) into a first region, wherein the first region is adjacent to and / or includes the pellicle (602); and outputting (711) a second fluid from a second set of one or more outlets (605) into a second region, the second region including the one or more optical elements of the projection system; wherein the second fluid is different from the first fluid; wherein the first fluid is a gas that is inert and / or chemically neutral to the pellicle (602); and The second fluid includes a gas and / or a plasma that degrades the surface film.

22. The method according to claim 21, wherein: The pattern forming device (601), the pellicle (602), one or more outlets of the first group, one or more outlets of the second group and the substrate are arranged so that a patterned radiation beam starts from the pattern forming device (601), then passes through the pellicle (602) adjacent to and / or included by the first area, then passes through the second area, and then reaches the substrate held by the substrate table.

23. The method according to claim 21 or 22, wherein: The method is performed by a lithographic apparatus according to any one of claims 1-20.

24. The method of claim 21, further comprising selecting the first fluid output by the first set of one or more outlets (603) depending on a type of diaphragm being used.

25. The method according to claim 21, wherein: Outputting the first fluid into the first region results in generating a first gas environment in the first region that protects the diaphragm (602) from the second region.

26. The method according to claim 21, wherein: Outputting the first fluid into the first region results in generating a first gas environment in the first region that prevents the fluid in the second region from reaching the diaphragm (602).

27. The method of claim 21, wherein the first fluid comprises one or more of helium, neon, argon, or nitrogen.

28. The method of claim 21, wherein the second fluid comprises a gas and / or plasma for preventing oxidation and contamination of the one or more optical elements of the projection system.

29. The method of claim 28, wherein the plasma is a hydrogen plasma.

30. The method of claim 28, wherein the second fluid comprises hydrogen radicals.

31. The method of claim 21, wherein the pellicle (602) is carbon-based, and wherein the first fluid comprises a carbon-containing gas.

32. A lithographic apparatus comprising: an irradiation system configured to condition the radiation beam; a patterning device configured to impart a pattern in a cross-section of the radiation beam to the radiation beam to form a patterned radiation beam; a substrate table (WT) configured to hold a substrate (W) in a substrate region (223); a projection system configured to project the patterned radiation beam onto a target portion of a substrate (W) while the substrate (W) is held by the substrate table (WT), wherein the projection system comprises one or more optical elements; a second set of one or more outlets (505) configured to output a second fluid to a second region (225) comprising the one or more optical elements of the projection system; and a third set of one or more outlets (220, 503) for outputting a third fluid to a third region (224), wherein the third region is adjacent to and / or includes the substrate region (223); and wherein the second fluid is different from the third fluid; wherein said third fluid is a gas that is inert and / or chemically neutral with respect to said substrate (W); and The second fluid comprises a gas and / or a plasma that degrades the substrate (W).

33. A lithographic apparatus according to claim 32, wherein the one or more outlets (220, 503) of the third group are configured to provide a third gas environment in the third region (224), the third gas environment protecting the substrate (W) from the second region (225).

34. A lithographic apparatus according to claim 32, wherein the substrate region (223) comprises a membrane (502) configured to cover a surface of the substrate (W), and wherein the third region (224) is adjacent to and / or comprises the membrane (502).

35. A lithographic apparatus according to claim 34, wherein the one or more outlets (220, 503) of the third group are configured to provide a third gas environment in the third region (224), the third gas environment protecting the membrane (W) from the second region (225).

36. A lithographic apparatus according to any one of claims 32 to 35, wherein: The pattern forming device (601), the projection system, one or more outlets (505) of the second group, one or more outlets (220, 503) of the third group and the substrate table (WT) are arranged so that, in use, a patterned radiation beam travels from the pattern forming device, passes through the projection system including the second area (225), passes through the third area (224), and then reaches a substrate (W) held by the substrate table (WT).

37. The lithographic apparatus of claim 32, wherein the third fluid comprises one or more of helium, neon, argon or nitrogen.

38. The lithographic apparatus of claim 32, wherein the second fluid comprises a gas and / or plasma for preventing oxidation and contamination of the one or more optical elements of the projection system.

39. The lithographic apparatus of claim 38, wherein the plasma is a hydrogen plasma.

40. The lithographic apparatus of claim 38, wherein the second fluid comprises a hydrogen radical.

41. The lithographic apparatus of claim 32, further comprising a third set of one or more inlets (504), the third set of one or more inlets (504) being arranged in the third region (224) for removing fluid from the third region (224).

42. A lithographic device according to claim 41, wherein the one or more inlets (504) of the third group are arranged on the side of the substrate (W) opposite to the one or more outlets (220, 503) of the third group, so that in use, there is a cross-flow of the third fluid across the substrate (W).

43. The lithographic apparatus according to claim 32, further comprising a second set of one or more inlets (506), the second set of one or more inlets (506) being arranged in the second region (225) for removing fluid from the second region (225).

44. A lithographic apparatus according to claim 43, wherein the second set of one or more inlets (506) are arranged on a side of the projection system opposite to the second set of one or more outlets (505) so that in use there is a cross-flow of the second fluid across the projection system.

45. The lithographic apparatus of claim 32, wherein the illumination system is configured to condition an extreme ultraviolet (EUV) radiation beam.

46. ​​The lithographic apparatus of claim 32, wherein one or more of the one or more optical elements are mirrors.

47. The lithographic apparatus of claim 32, further comprising a control system configured to select a third fluid to be output from the third set of one or more outlets (220, 503) depending on a type of substrate or membrane being used.

48. The lithography device according to claim 32 further includes a second fluid supplier (508) containing the second fluid and a third fluid supplier (507) containing the third fluid, wherein the second fluid supplier (508) is fluidically connected to one or more outlets (505) of the second group, and the third fluid supplier (508) is fluidically connected to one or more outlets (503) of the third group.

49. A method comprising: regulating the radiation beam; imparting, by a patterning device, a pattern in a cross-section of the radiation beam to the radiation beam to form a patterned radiation beam; projecting the patterned radiation beam onto a target portion of a substrate held in a substrate region by a projection system, wherein the projection system includes one or more optical elements; outputting a second fluid from a second set of one or more outlets into a second region including the one or more optical elements of the projection system; and outputting a third fluid into a third region from a third set of one or more outlets, wherein the third region is adjacent to and / or includes the substrate region; and wherein the second fluid is different from the third fluid, wherein the third fluid is a gas that is inert and / or chemically neutral to the substrate; and The second fluid includes a gas and / or a plasma that degrades the substrate.

50. The method of claim 49, wherein a third fluid output into the third region provides a third gas environment in the third region, the third gas environment protecting the substrate from the second region.

51. The method of claim 49, wherein the substrate region comprises a membrane configured to cover a surface of the substrate, and wherein the third region adjoins and / or comprises the membrane.

52. The method of claim 51, wherein the third fluid output into the third region provides a third gas environment in the third region, the third gas environment protecting the membrane from the second region.

53. The method according to any one of claims 49 to 52, wherein: The pattern forming device, the diaphragm, the one or more outlets of the second group, the one or more outlets of the third group and the substrate are arranged so that the patterned radiation beam travels from the pattern forming device, passes through the second region, passes through the third region, and then reaches the substrate held by the substrate table.

54. The method of claim 49, wherein: The method is performed by a lithographic apparatus according to any one of claims 32-48.

55. The method of claim 49, further comprising selecting the third fluid output by the third set of one or more outlets depending on the type of substrate or membrane being used.

56. The method of claim 49, wherein the third fluid comprises one or more of helium, neon, argon, or nitrogen.

57. The method of claim 49, wherein the second fluid comprises a gas and / or plasma for preventing oxidation and contamination of the one or more optical elements of the projection system.

58. The method of claim 57, wherein the plasma is a hydrogen plasma.

59. The method of claim 57, wherein the second fluid comprises hydrogen radicals.

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