JP7366913B2 - Apparatus and method for controlling debris in an EUV light source - Google Patents

Description

(Cross reference to related applications)
[00001] This application claims priority to US Application No. 62/648,505, filed March 27, 2018. This application is incorporated by reference in its entirety.

[00002] The present disclosure relates to apparatus and methods for generating extreme ultraviolet ("EUV") radiation from a plasma produced by electrical discharge or laser ablation of a target material within a container. In such applications, optical elements are used to collect and direct radiation for use in semiconductor photolithography and inspection, for example.

[00003] For example, extreme ultraviolet radiation, such as electromagnetic radiation (sometimes referred to as soft x-rays) having a wavelength of about 50 nm or less, including radiation with a wavelength of about 13.5 nm, may be used in photolithography processes. , can produce extremely small features on substrates such as silicon wafers.

[00004] A method for generating EUV radiation includes converting a target material to a plasma state. The target material preferably comprises at least one element, such as xenon, lithium or tin, which has one or more emission lines in the EUV part of the electromagnetic spectrum. Target materials may be solid, liquid, or gaseous. One such method, often referred to as laser produced plasma (“LPP”), uses a laser beam to irradiate a target material with the required line-emitting elements to generate the required It is possible to generate a large amount of plasma.

[00005] One LPP technique includes generating a stream of target material droplets and irradiating at least a portion of the droplets with one or more pulses of laser radiation. Such LPP sources generate EUV radiation by coupling laser energy to a target material having at least one EUV-emitting element and creating a highly ionized plasma with an electron temperature of several tens of eV.

[00006] For this process, a plasma is typically generated in a closed container, such as a vacuum chamber, and the resulting EUV radiation is monitored using various types of metrology equipment. In addition to producing EUV radiation, the processes used to generate plasma typically also produce undesirable by-products within the plasma chamber. This by-product can include out-of-band radiation, energetic ions, and debris such as atoms and/or clumps/microdroplets of residual target material.

[00007] Energy radiation is emitted from the plasma in all directions. In one common configuration, a near-normal incidence mirror (also referred to as a "collector mirror" or simply "collector") is used to collect and direct at least a portion of the radiation to an intermediate location, and in some configurations for further focusing. ) is positioned. The collected radiation can then be transmitted from an intermediate location to an optics set, a reticle, a detector, and finally to a silicon wafer.

[00008] In the EUV portion of the spectrum, it is generally believed that it is necessary to use reflective optics for the optical elements of the system, including the collector, illuminator, and projection light box. These reflective optics can be implemented as normal incidence optics as described above or as grazing incidence optics. At the relevant wavelengths, the collector is advantageously implemented as a multi-layer mirror (MLM). As the name suggests, this MLM generally consists of alternating layers of material (MLM stack) on a base or substrate. Additionally, the system optics can be configured as coated optical elements even if not implemented as an MLM.

[00009] Optical elements, particularly collectors, must be placed in the vessel with the plasma to collect and redirect the EUV radiation. The environment within the chamber is detrimental to the optical element, eg reducing its reflectance and limiting its service life. Optical elements within the environment may be exposed to energetic ions or particles of the target material. Particles of target material, which are essentially debris from the laser vaporization process, can contaminate the exposed surfaces of the optical elements. Also, particles of target material can cause physical damage and localized heating to the MLM surface.

[00010] In some systems, H ₂ gas at a pressure within the range of about 0.5 to about 3 mbar is used within the vacuum chamber as a buffer gas for debris mitigation. In the absence of gas, vacuum pressure is difficult to adequately protect the collector from target material debris emitted from the irradiation area. Hydrogen is relatively transparent to EUV radiation with a wavelength of about 13.5 nm, thus making it more attractive to other candidates such as He, Ar, or other gases that have higher absorption at about 13.5 nm. More suitable than gas.

[00011] _H2 gas is introduced into the vacuum chamber to slow down high-energy debris (ions, atoms, and clumps) of the target material created by the plasma. Debris is slowed down by collisions with gas molecules. For this purpose, the flow of H ₂ gas used can be opposite to the debris trajectory and away from the collector. This serves to reduce the damage of target material deposition, implantation, and sputtering to the optical coating of the collector.

[00012] Nevertheless, one of the most difficult challenges in radiation sources such as those described is the management of residual target material. The process of converting target material into vapor and particles leaves residual target material on all surfaces in its unobstructed path to and from the irradiation site, as well as on surfaces in the exit path of gases carrying residual target material. accumulate. For example, if this gas is pumped through the top of vanes present in the chamber to a mechanical pump, material will be deposited on all of the cold metal parts. If the target material is tin, this can result in tin wool that can fall into the collector optics or clog the ejection path.

[00013] Continuing with tin as an example of a target material, one technique for controlling tin diffusion involves capturing tin from vapor or particles on a surface heated above the melting point of tin. include. There, the tin melts (or remains molten) and flows into the capture receptacle. However, liquid tin tends to eject or "spit" in the presence of hydrogen radicals, such as those observed in EUV chambers, and this spewed tin can land on the collector. . This is a major cause of collector deterioration. Second, liquid tin usually does not flow as intended. For example, liquid tin may drip onto the collector from structures within the chamber, such as scrubber vanes and gutters that are provided to remove some or all of the tin vapor within the chamber. Additionally, the scrubber groove may flood and liquid tin may travel down the back of the vane, creating a thermal short (ie, an unintended heat transfer path) and clogging the flow path to the capture receptacle. Additionally, liquid tin is highly corrosive, causing failure of, for example, electric heaters used to maintain the collection surface above the tin melting point. Tin deposition also significantly increases collector degradation because the flow restriction caused by tin accumulation forces the gas path in the vanes and collector into narrow spaces.

[00014] As previously mentioned, scrubbers can be added to areas such as the top of the blades to capture tin present in the steam by condensing it from the steam. Maintaining the scrubber surface above the melting point of tin allows liquid tin to flow through the vanes and reach the receptacle. However, liquid tin in the scrubber may still splash onto the collector and drip onto the collector through the grooves, increasing collector deterioration. There is also a problem in maintaining the scrubber at a temperature higher than the melting point of tin. If the temperature of the scrubber is below the melting point of tin, the tin will solidify and clog the scrubber. Altering the geometry of the scrubber, for example by changing the size and slope of the scrubber blades, may improve performance but completely eliminates the tendency for scrubber to spray onto the collector or cold surfaces and clog the exhaust. It cannot be resolved.

[00015] The process of generating EUV light may also cause target material to be deposited on the walls of the container. Controlling target material deposition on the walls of the vessel is important to achieving an acceptable long lifetime of an EUV source in operation. Additionally, managing the target material flux from the irradiation site is important to ensure that the waste target material mitigation system functions as intended.

[00016] The following presents a simplified summary of one or more embodiments in order to provide a basic understanding of those embodiments. This summary is not an extensive overview of all contemplated embodiments, and does not attempt to identify key or essential elements of all embodiments and does not attempt to identify key or essential elements of any or all embodiments. Nor is it intended to impose any limitations on the scope of the embodiments. Its sole purpose is to present some concepts of one or more embodiments in a simplified form as a prelude to the more detailed description that is presented later.

[00017] According to one aspect, different tin management techniques are used for different portions of the "tin path," ie, the path from the chamber liner to the imaging relay mirror that redirects light exiting the chamber. A combination of solid and liquid tin techniques is used with an exhaust manifold to manage the dispersion and collection of tin. Zones in the exhaust stream are identified and in each of these zones, appropriate techniques are used to treat the exhaust gas stream based on different requirements.

[00018] According to another aspect of embodiments, an apparatus for generating EUV radiation is disclosed. The apparatus includes a container, a first location configured to collect residual target material from the irradiation area, and a wall of the container configured to release residual target material collected at the first location. a second location shielded from the interior of at least a portion of the target material; and maintaining the residual target material collection surface at a temperature below the melting point of the target material in the first location and a second location. a temperature controller configured to maintain a temperature above the melting point of the target material at the location of the target material. The residual target material collection surface may include the surface of the belt. The belt may be cooled in the first position and heated in the second position. The apparatus may further include at least one scrubber positioned adjacent the belt at the second location and configured to remove residual target material from the belt. At least one scrubber may be positioned such that residual target material removed from the belt flows by gravity to the receptacle. The apparatus may further include a chamber exhaust manifold in fluid communication with the chamber. The chamber exhaust manifold has a liner, and at least a portion of the liner can be heated. The residual target material collection surface may include a shield. The shield may be cooled in the first position and heated in the second position. The shield may be configured to pivot from a first position to a second position. The shield may be configured to move laterally from a first position to a second position. The second location may be selected such that molten residual target material flows from the shield to the receptacle by gravity. The apparatus may further include a chamber exhaust manifold in fluid communication with the chamber. The chamber exhaust manifold has a liner, and at least a portion of the liner can be heated.

[00019] According to one aspect of an embodiment, a method of collecting residual target material in an apparatus for generating EUV radiation is disclosed. The method includes the steps of accumulating residual target material on a surface at a first location, the surface being at a temperature below the melting point of the target material; and removing the molten residual target material from the surface. Removing molten residual target material from the surface may include scraping molten residual target material from the surface. Removing molten residual target material from the surface may include flowing molten residual target material from the surface. After the removing step, the method may further include flowing the removed molten residual target material into the receptacle.

[00020] Further embodiments, features, and advantages of the invention, as well as the structure and operation of various embodiments, are described in detail below with reference to the accompanying drawings.

[00021] FIG. 1 is a schematic, not-to-scale diagram illustrating the general broad concept of a laser-produced plasma EUV radiation source system according to an aspect of the invention. [00022] FIG. 4 is a not-to-scale diagram illustrating a possible configuration of a container and evacuation system used in a laser-produced plasma EUV radiation source system according to an aspect of the invention. [00023] FIG. 3 is a not-to-scale diagram illustrating a possible configuration of a vessel target material control system used in a laser-produced plasma EUV radiation source system according to an aspect of the invention. [00024] A diagram not to scale illustrating a possible configuration of a target material control system for a vessel throat portion used in a laser-produced plasma EUV radiation source system according to an aspect of an embodiment of the invention. It is. [00025] FIG. 9 is a not-to-scale diagram illustrating another possible configuration of a target material control system for a vessel tubular section used in a laser-produced plasma EUV radiation source system according to an aspect of an embodiment of the invention; . [00026] FIG. 5 is a diagram not to scale illustrating another possible configuration of target material control system elements for a tubular portion of a vessel used in a laser-produced plasma EUV radiation source system according to an aspect of an embodiment of the invention. be. [00027] FIG. 5A is a top view of the configuration of FIG. 5A. [00028] FIG. 3 is a not-to-scale diagram illustrating additional elements of a target material control system element for a tubular portion of a vessel used in a laser-produced plasma EUV radiation source system according to an aspect of an embodiment of the invention.

[0029] Further features and advantages of the invention, as well as the structure and operation of various embodiments of the invention, are described in detail below with reference to the accompanying drawings. Note that the invention is not limited to the particular embodiments described herein. Such embodiments are described herein by way of example only. Additional embodiments will readily occur to those skilled in the art based on the teachings contained herein.

[00030] Various embodiments will now be described with reference to the drawings. Like reference numbers are used to refer to like elements throughout the drawings. In the following description, for purposes of explanation, numerous specific details are set forth to facilitate a thorough understanding of one or more embodiments. It is clear, however, that in some or all cases, any of the embodiments described below may be practiced without employing such specific design details described below. Will. In some instances, well-known structures and devices are shown in block diagram form in order to facilitate describing one or more embodiments.

[00031] Before describing such embodiments in detail, it may be helpful to present an exemplary environment in which embodiments of the invention may be implemented. In the following description and claims, "up", "down", "top", "bottom", "vertical", "horizontal", etc. terminology such as "horizontal)" may be used. These terms are intended to indicate relative orientation only, and not absolute orientation, such as orientation relative to gravity, unless otherwise indicated.

[00032] Referring first to FIG. 1, a schematic diagram of an exemplary EUV radiation source, such as a laser-produced plasma EUV radiation source 10, is shown, in accordance with one aspect of an embodiment of the present invention. As shown, EUV radiation source 10 may include a pulsed or continuous laser source 22. This may be, for example, a pulsed gas discharge CO ₂ laser source producing a radiation beam 12 of 10.6 μm or 1 μm. Pulsed gas discharge _CO2 laser sources may have DC or RF excitation operating at high power and high pulse repetition rates.

[00033] EUV radiation source 10 also includes a target delivery system 24 for delivering target material in the form of droplets or a continuous liquid stream. In this example, the target material is a liquid, but it may also be a solid or a gas. The target material can be comprised of tin or a tin compound, although other materials can also be used. In the illustrated system, a target material delivery system 24 introduces a droplet 14 of target material into an irradiation region 28 inside a vacuum chamber 26 . The target material can now be irradiated to generate plasma. Vacuum chamber 26 may include a liner. In some cases, an electrical charge is applied to the target material to enable it to be directed toward or away from the irradiation region 28 . As used herein, an irradiated area is an area where target material irradiation can or is intended to occur, even when no irradiation is actually occurring. It should be noted that The EUV light source may also include a beam steering system 32.

[00034] The components in the illustrated system are arranged so that the droplet 14 travels in a substantially horizontal direction. The direction from the laser source 22 toward the irradiation region 28, ie, the nominal direction of propagation of the beam 12, can be considered the Z-axis. The path that droplet 14 follows from target material delivery system 24 to irradiation region 28 can be thought of as the X-axis. The view of FIG. 1 is therefore perpendicular to the XZ plane. The orientation of the EUV radiation source 10 is preferably rotated relative to gravity as shown. Arrow G indicates the preferred orientation with respect to the downward direction of gravity. This orientation applies to the EUV source, but not necessarily to optically downstream components such as scanners. Also, although a system is illustrated in which the droplet 14 travels in a substantially horizontal direction, it is also possible for the droplet to travel in a vertical direction or between 90 degrees (horizontal) and 0 degrees (vertical) relative to gravity. It will be appreciated by those skilled in the art that other configurations advancing at angles in between (and inclusive) may also be used.

[00035] The EUV radiation source 10 may also include an EUV source controller system 60, a laser firing control system 65, as well as a beam steering system 32. The EUV radiation source 10 may also include a detector, such as a target position detection system, which may include one or more droplet imagers 70. The droplet imager generates an output indicative of, for example, the absolute or relative position of the target droplet with respect to the illumination area 28 and provides this output to the target position detection feedback system 62 .

[00036] As shown in FIG. 1, target material delivery system 24 may include a target delivery control system 90. Target delivery control system 90 operates in response to a signal, such as the target error described above, or some amount derived from the target error provided by system controller 60, to control the delivery of target droplet 14 through illumination region 28. Adjust the route. This can be accomplished, for example, by repositioning the point at which target delivery mechanism 92 releases target droplet 14. The droplet release point can be repositioned by, for example, tilting the target delivery mechanism 92 or translating the target delivery mechanism 92 laterally. Target delivery mechanism 92 extends into chamber 26 and is supplied, preferably externally, with target material and a gas source to place the target material within target delivery mechanism 92 under pressure.

[00037] With continued reference to FIG. 1, radiation source 10 may also include one or more optical elements. In the discussion below, collector 30 is used as an example of such an optical element, but the discussion below also applies to other optical elements. The collector 30 may be a normal incidence reflector, for example implemented as an MLM, with an additional thin barrier layer deposited at each interface, e.g. B ₄ C, ZrC, Si ₃ N ₄ or C to effectively inhibits interlayer diffusion induced by Other substrate materials such as aluminum (Al) or silicon (Si) can also be used. The collector 30 may be in the form of a prolate ellipsoid, with a central aperture allowing the laser radiation 12 to pass through to the irradiation area 28 . The collector 30 may be, for example, elliptical, with a first focus in the irradiation area 28 and a second focus at a so-called intermediate point 40 (also referred to as intermediate focus 40). At an intermediate point 40, EUV radiation may exit the EUV radiation source 10 and enter, for example, an integrated circuit lithography scanner 50. An integrated circuit lithography scanner 50 uses this radiation to process a silicon wafer workpiece 52 in known manner, for example using a reticle or mask 54. The silicon wafer workpiece 52 is then further processed in known manner to obtain integrated circuit devices.

[00038] The configuration of FIG. 1 also includes a temperature sensor 34. This is for example a thermocouple placed in the chamber 26 in order to measure the local temperature, ie the temperature of the gas in the chamber 26 at this sensor. Although FIG. 1 shows one temperature sensor, it will be appreciated that additional temperature sensors can be used. Temperature sensor 34 generates a signal indicative of the measured temperature and provides this as an additional input to controller 60. Controller 60 generates a control signal to provide to beam steering system 32 based at least in part on this temperature signal.

[00039] Deposition of target material debris on the wall of the container directly above the collector creates a risk of target material dripping onto the collector. The black double arrow in FIG. 2 indicates the direction of debris propagation. The white arrows indicate a preferred configuration for flowing _H2 away from the collector 30. Element 42 is a scrubber for removing contaminants from the _H2 . Arrow G indicates the direction of gravity. Also shown is a line 13 indicating the division between the radiation source 10 and the scanner 50.

[00040] FIG. 3 shows a chamber design with an asymmetric exhaust with a large tubular area. The design of FIG. 3 has two outlets 60. This design allows a large amount of tin to be deposited at location 70 on the wall of the exhaust manifold opposite this large tubular section. If this surface is maintained at a temperature above the melting point of tin, there is a risk of molten tin splashing onto the collector.

[00041] In a system according to an aspect of an embodiment of the invention, the tin is melted or in a liquid state at a location where there is no possibility or a low possibility that splashes of liquid tin will be applied to the interior of the chamber or the collector. to be maintained. High flow conductance can be maintained and exhaust gases are scrubbed. According to another aspect, tin can be ejected during operation of the radiation source in situ.

[00042] An example of such a system is shown in FIG. 4A. Tin debris from the irradiation area 28 is captured by two heated scrubbers 80. These scrubbers 80 are located in each hot zone and are completely protected from splashing on the interior surface 84 of the chamber 26, which includes a liner 84 that at least partially covers the exhaust plenum wall 86. A portion 88 of liner 84 adjacent scrubber 80 may be heated above the melting point to "drip off" excess solid tin. These surfaces are also protected from splashing onto the collector.

[00043] As further shown in FIG. 4A, this configuration includes an endless belt 90 covering a portion of the rear or outer wall 94 of the exhaust plenum. Sandwiched between the belts 90 are cold (eg, water-cooled) plates 92 that are in contact or nearly in contact to maintain the surfaces at a temperature well below the melting point of tin. Therefore, solid tin particles entering this area remain solid and tin vapor entering this area becomes solid.

[00044] In order to convey this solid tin to the high-temperature scrubber 80, the belt 90 can be moved continuously, moved intermittently, or moved forward stepwise at regular intervals. When the endless belt 90 hits the hot scrubber 80, the heated doctor blade melts the tin and allows the belt 90 to be scrubbed clean, and the belt 90 returns to the deposition area to collect more tin. This configuration ensures that tin droplets do not get onto the collector or liner. Belt 90 is preferably placed in areas where the highest tin deposits are expected, such as tubular areas.

[00045] Another example of such a system is shown in FIG. 4B. Again, tin debris from the irradiation area 28 is captured by two heated scrubbers 80 located in each hot zone and completely protected from splashing on the inner surface 84 of the liner 86 and the collector. . As further shown in FIG. 4B, this configuration includes a wedge-shaped diverter 96 positioned at the tubular outlet on the wall of the exhaust plenum. Direction device 96 directs the flow of debris from irradiation region 28 (white arrows) to a portion of the exhaust manifold that is shielded from irradiation region 28 (curved arrow). The direction of the transported/deposited molten tin droplets tends toward the scrubber 80 but not back into the interior of the vacuum vessel. Due to its shape, the directing device 94 directs the flow of exhaust gases and entrained debris away from the rear wall of the tubular outlet and directly into the scrubber. Typically, the induction device 96 is cooled to a temperature below the melting point of the target material, but it can also be heated to a temperature above the tin melting point to cause the solid tin accumulated on the induction device 96 to flow to the tin drain. Since the majority of the tin is sprayed perpendicular to the surface of the guiding device 96 facing away from the interior of the chamber 26, the amount of spray that travels to the optics within the tool is severely limited.

[00046] Some attention must be paid to the roof of the liner at the opening to the large tubular section. These roof and floor areas are typically sloped and recessed to protect the collector/liner as much as possible.

[00047] It is also possible to cover other areas with high accumulation with water cooling shields. The shield can be rotated by a hinge to the rear of the opening for dripping. Such a configuration is shown in FIGS. 5A and 5B. FIG. 5A shows a tubular area with a shield 110. The shield 110 is connected to the wall of the tube by a hinge 112 and can be pivoted to the rear of the aperture to place it in a position (shown in phantom) to drop the tin by heating. FIG. 5B is a top view of the configuration of FIG. 5A showing rotation of shield 110 about hinge 112. These shields 110 can be positioned to minimize adverse effects on conductivity and so that liquid tin droplets do not have an open path to the collector or liner.

[00048] Variations on the embodiments described above are possible that represent the spirit of this disclosure. According to one aspect of the disclosed embodiments, solid tin temperature surfaces are presented in areas that are likely to overspray the liner and collector. The tin can then be removed by any of several methods, including thermal cycling of the surface, ie, temporarily raising the temperature of the surface to a temperature above the melting point of the tin. Alternatively or additionally, it is also possible to move the surface into a shielded position for dripping or to cover it during dripping. According to another aspect, liquid tin is recovered (washed down) from the gas stream and delivered to a suitable isolated location for draining (eg, there is no open path to the collector or liner). The upstream wall of the scrubber can be maintained at a temperature that allows the tin to drip. According to another aspect, in areas of high deposition, thermal cycling, moving liner sections to a safe position for dripping, ion generation for cleaning and to maintain clean conditions, or Partial covers can be used.

[00049] FIG. 6 shows a tubular section 100 located as high as possible in the chamber in order to limit the amount of excess debris between plasma on and off, that is, when plasma is being generated and when plasma is not being generated. An embodiment in which the is moved is shown. This increases debris evacuation efficiency and limits the amount of debris that accumulates on the inner wall surface. In this embodiment, the endless belt 90 of the embodiment of FIG. 4A can be used, or a heating plate can be placed at the output of the tubular section 100. The exhaust manifold is made circular (tube-like) and thus can have a round scrubber 110 rather than a rectangular scrubber. A tin drain 115 collects molten tin and sends it to a tin bucket or receptacle 117. Freeze valve 119 allows emptying of tin receptacle 117 via conduit 121 without interfering with operation of the radiation source. Tin drains can be placed on both sides of the radiation source.

[00050] The above description includes examples of one or more embodiments. Of course, it is not possible to list all possible combinations of components or methods for the purpose of describing the embodiments described above, and many other combinations and permutations of the various embodiments are possible to those skilled in the art. It can be acknowledged that this is the case. Accordingly, the described embodiments are intended to cover all such alternatives, modifications, and variations falling within the spirit and scope of the appended claims. Further, to the extent that the term "include" is used either in the Detailed Description or in the claims, such terminology does not apply to the claims. is intended to be inclusive, as is to be construed when used as a transitional word. Furthermore, although elements of the described aspects and/or embodiments may be described or claimed in the singular, the plural is also contemplated unless limitation to the singular is explicitly stated. Furthermore, unless stated otherwise, all or a portion of any aspect and/or embodiment may be utilized with all or a portion of any other aspect and/or embodiment.

[00051] Other aspects of the invention are set forth in the numbered sections below.
1. A device for generating EUV radiation, the device comprising:
a container and
a first location configured to collect residual target material from the irradiation area; and from within at least a portion of the wall of the container configured to release residual target material collected at the first location. a residual target material collection surface having a shielded second location;
a temperature controller configured to maintain the residual target material collection surface at a temperature below the melting point of the target material at the first location and above the melting point of the target material at the second location;
A device comprising:
2. 2. The apparatus of clause 1, wherein the residual target material collection surface comprises a surface of a belt.
3. Apparatus according to clause 2, wherein the belt is cooled in the first position and heated in the second position.
4. 3. The apparatus of clause 2, further comprising at least one scrubber positioned adjacent the belt in the second location and configured to remove residual target material from the belt.
5. 5. The apparatus of clause 4, wherein the at least one scrubber is positioned such that residual target material removed from the belt flows by gravity into the receptacle.
6. The apparatus of clause 1, further comprising a chamber exhaust manifold in fluid communication with the chamber.
7. 7. The apparatus of clause 6, wherein the chamber exhaust manifold has a liner, and at least a portion of the liner is heated.
8. The apparatus of clause 1, wherein the residual target material collection surface includes a shield.
9. 9. The apparatus of clause 8, wherein the shield is cooled in the first position and heated in the second position.
10. 9. The apparatus of clause 8, wherein the shield is configured to pivot from the first position to the second position.
11. 9. The apparatus of clause 8, wherein the shield is configured to move laterally from the first position to the second position.
12. 9. The apparatus of clause 8, wherein the second position is selected such that the molten residual target material flows from the shield to the receptacle by gravity.
13. 9. The apparatus of clause 8, further comprising a chamber exhaust manifold in fluid communication with the chamber.
14. 14. The apparatus of clause 13, wherein the chamber exhaust manifold has a liner, and at least a portion of the liner is heated.
15. A method for collecting residual target material in an apparatus for generating EUV radiation, the method comprising:
accumulating residual target material on the surface at the first location, the surface being at a temperature below the melting point of the target material;
moving the surface to a second location where the surface is at a temperature higher than the melting point of the residual target material to melt the residual target material;
removing molten residual target material from the surface;
method including.
16. 16. The method of clause 15, wherein the step of removing molten residual target material from the surface comprises scraping the molten residual target material from the surface.
17. 16. The method of clause 15, wherein the step of removing molten residual target material from the surface comprises flowing molten residual target material from the surface.
18. 16. The method of clause 15, further comprising flowing the removed molten residual target material into the receptacle after the removing step.

Claims (18)

A device for generating EUV radiation, the device comprising:
a container and
a first location configured to collect residual target material conveyed from the irradiation region; and a first location of the irradiation region and the container configured to release residual target material collected at the first location. a second location shielded from the interior of at least a portion of the wall; a residual target material collection surface having a second location;
a temperature configured to maintain the residual target material collection surface at a temperature below the melting point of the target material at the first location and above the melting point of the target material at the second location; controller and
A device comprising: 2. The apparatus of claim 1, wherein the residual target material collection surface includes a surface of a belt. 3. The apparatus of claim 2, wherein the belt is cooled in the first position and heated in the second position. 3. The apparatus of claim 2, further comprising at least one scrubber positioned adjacent the belt in the second position and configured to remove residual target material from the belt. 5. The apparatus of claim 4, wherein the at least one scrubber is positioned such that residual target material removed from the belt flows by gravity into a receptacle. The apparatus of claim 1, further comprising a chamber exhaust manifold in fluid communication with the chamber. 7. The apparatus of claim 6, wherein the chamber exhaust manifold includes a liner, and at least a portion of the liner is heated. 2. The apparatus of claim 1, wherein the residual target material collection surface includes a shield. 9. The apparatus of claim 8, wherein the shield is cooled in the first position and heated in the second position. 9. The apparatus of claim 8, wherein the shield is configured to pivot from the first position to the second position. 9. The apparatus of claim 8, wherein the shield is configured to move laterally from the first position to the second position. 9. The apparatus of claim 8, wherein the second location is selected such that molten residual target material flows from the shield to a receptacle by gravity. 9. The apparatus of claim 8, further comprising a chamber exhaust manifold in fluid communication with the chamber. 14. The apparatus of claim 13, wherein the chamber exhaust manifold includes a liner, and at least a portion of the liner is heated. A method for collecting residual target material in an apparatus for generating EUV radiation, the method comprising:
accumulating residual target material carried from the irradiation region on a surface at a first location, the surface being at a temperature below the melting point of the target material;
moving the surface to a second location shielded from the irradiation area to melt the residual target material , the surface in the second location having a temperature above the melting point of the residual target material; The steps are :
removing the molten residual target material from the surface;
method including. 16. The method of claim 15, wherein the step of removing the molten residual target material from the surface includes scraping the molten residual target material from the surface. 16. The method of claim 15, wherein the step of removing the molten residual target material from the surface includes flowing the molten residual target material from the surface. 16. The method of claim 15, further comprising flowing the removed molten residual target material into a receptacle after the removing step.

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