CN115803551A - Device for protecting fluid lines in EUV sources - Google Patents

Abstract

A source material valve is placed in a fluid supply line for a source material chamber (such as a source material refill reservoir) to prevent molten source material in the chamber from reaching and thus contaminating and plugging the fluid supply line upstream of the source material valve in the event of a pressure failure.

Description

Device for protecting fluid lines in EUV sources

Cross References to Related Applications

This application claims priority to U.S. Patent Application 63/052,184, filed July 15, 2020, entitled "APPARATUS FOR PROTECTING FLUID LINES IN AN EUV SOURCE," the entirety of which The contents are incorporated herein by reference.

technical field

The present disclosure relates to the protection of fluid lines for pressurizing source material chambers in systems for generating extreme ultraviolet radiation.

Background technique

Extreme ultraviolet ("EUV") radiation, such as electromagnetic radiation having a wavelength of about 50 nm or less (sometimes referred to as soft x-rays), including light of a wavelength of about 13.5 nm, is used in photolithography to Very small features are created on a substrate, such as a silicon wafer. The term "light" is used here and elsewhere herein, although it is understood that the radiation described using this term may not be in the visible portion of the spectrum.

The method used to generate EUV light involves converting the source material from a liquid state to a plasma state. The source material preferably comprises at least one element (eg xenon, lithium or tin) having one or more emission lines in the EUV range. In one such method, commonly referred to as laser-produced plasma ("LPP"), the desired plasma can be generated by irradiating a source material with the desired line-emitting element with a laser beam.

Source material may take one of many forms. It can be solid or molten. If molten, it can be dispensed in several different ways, such as in a continuous stream or a stream of droplets. As an example, in most of the discussion that follows, the source material is molten tin dispensed as a stream of droplets. However, one of ordinary skill in the art will appreciate that other forms of source material, forms of source material, and modes of delivery may be used.

Thus, one LPP technique involves generating a stream of source material droplets and irradiating at least some of the droplets with laser pulses in a vacuum chamber. In more theoretical terms, LPP sources generate EUV radiation by depositing laser energy into a source material with at least one EUV emitting element, thereby generating a highly ionized plasma.

The high-energy radiation generated during the de-excitation and recombination of these ions is emitted from the plasma in all directions. In one common setup, an approximately normal incidence mirror (often referred to as a "collector mirror" or simply "collector") is positioned to collect, direct, and, in some setups, focus the light onto centre position. The collected light is then relayed from an intermediate location to a set of scanner optics and ultimately to the substrate.

The droplet stream is generated by a source material dispenser, such as a droplet generator. The portion of the droplet generator that releases the droplets (sometimes referred to as the nozzle or nozzle assembly) is located within the vacuum chamber. The drop generator nozzle assembly requires a constant supply of source material. This source material is typically supplied by a supply of source material held in a source material chamber or series of source material chambers. Source material must be transferred from the source material chamber to the nozzle assembly. This can be achieved by pressurizing the molten source material and flowing it through a conduit maintained above the melting point of the source material.

In each chamber, molten source material is subjected to a fluid under pressure to drive the source material through a heated conduit. Fluid is introduced into the reservoir through a fluid supply line. Because the molten source material is also under pressure from other parts of the system, it is possible for the molten source material to fill the chamber and begin to flow into the fluid supply line. This can cause problems such as the source material solidifying and clogging the fluid lines.

Furthermore, in a multi-chamber system, there are different source material chambers for different purposes. For example, unidirectional flow between the chambers may be required to prevent contaminated source material from flowing into and mixing with the purified source material.

It is in these contexts that the subject matter disclosed and claimed herein may be advantageous.

Contents of the invention

In order to provide a basic understanding of the embodiments, a brief summary of one or more embodiments is presented below. This summary is not an extensive overview of all contemplated embodiments and is intended to neither identify key or critical elements of all embodiments nor delineate the scope of any or all embodiments. Its 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.

According to one aspect of the embodiments, a source material valve is disclosed that is placed in a fluid supply line for a source material chamber, such as a source material refill reservoir, to prevent melting in the chamber The source material reaches and thus contaminates and clogs the fluid supply line upstream of the source material valve in the event of a pressure failure.

According to another aspect of the embodiments, an apparatus for controlling the flow of molten source material from a source material holding chamber in an EUV source is disclosed, the apparatus comprising a valve body defining a cavity, the valve body having a shape adapted to be A first valve body end connected to a fluid supply line and a second valve body end adapted to be placed in fluid communication with a source material holding chamber having at the end of the cavity closer to the first valve body end a seat wall, the inner part is disposed in the cavity and is adapted to move from a first position, in which the inner part permits fluid flow through the cavity, to a second position, in which the upper part of the inner part sits against the seat wall to prevent molten source material from flowing through the cavity.

According to another aspect of the embodiments, an apparatus for controlling the flow of molten source material from a chamber in an EUV source is disclosed, the apparatus comprising a valve body defining a vertical chamber when vertically arranged chamber, the valve body has an upper valve body end adapted to be connected to a fluid supply line and a lower valve body end adapted to be in fluid communication with the chamber, the cavity has a seat wall at the upper end of the cavity and an inner part, the inner part Disposed in the cavity and adapted to be moved vertically by molten source material entering the cavity through the lower valve body end from a first position in which the internal component permits fluid flow through the cavity to a second position in which In a second position, the upper portion of the inner member moves toward and makes sealing contact against the seat wall to prevent molten source material from flowing through the cavity.

According to another aspect of the embodiments, an apparatus for controlling the flow of molten source material from a chamber in an EUV source is disclosed, the apparatus including a valve body defining the chamber, the valve body having a shape adapted to be connected to a first valve body end of the fluid supply line and a second valve body end adapted to be placed in fluid communication with a chamber having a seat wall at an end closer to the valve body end; and a an inner member adapted to have a first state in which the inner member permits fluid flow through the cavity, and a second state in which the cavity is partially filled with molten source material and in a second state In a state, due to the molten source material in the cavity, the internal component prevents the molten source material from flowing through the cavity.

According to another aspect of the embodiments, an apparatus for controlling the flow of molten source material between a first source material holding chamber and a second source material holding chamber in an EUV source is disclosed, the apparatus comprising defining a cavity a valve body of the cavity, the valve body having a first valve body end adapted to be in fluid communication with the connected first source material holding chamber and a second valve body end adapted to be in fluid communication with the second source material holding chamber, The cavity has a seat wall at the end near the first valve body end, and an inner part arranged in the cavity, the inner part is adapted to move from a first position to a second position, in the first position, the inner part allows the source Material flows through the cavity from the first source material holding chamber to the second source material holding chamber, and in the second position, the upper portion of the inner member sits against the seat wall to prevent molten source material from passing through the cavity from the second source material The material holding chamber flows to the first source material holding chamber.

According to a further aspect of the embodiment, the inner component may include a generally cylindrical body and a plurality of airfoil members disposed about a lower perimeter of the generally cylindrical body. The plurality of airfoil members may include at least three airfoil members arranged in a rotationally symmetrical pattern around the lower periphery of the generally cylindrical body, for example the plurality of airfoil members may include six airfoil members, the six airfoil members are arranged at intervals of 60 degrees around the lower perimeter of the generally cylindrical body. The outside of the airfoil member may be rounded.

According to further aspects of the embodiments, the inner component may be solid and include a material having a density less than that of the molten source material. If the molten source material is molten tin, the internal component may comprise, for example, titanium or a titanium alloy. The inner part may have a spherical upper surface of radius R and the seat wall may have a complementary spherical surface of radius R. The inner part may have a tapered lower portion. The apparatus may also include a heater in thermal contact with the valve body and adapted to maintain the temperature of the valve body and internal components above the melting point of the source material. The valve body may include molybdenum.

Further embodiments, features, and advantages of the disclosed subject matter, as well as the structure and operation of various embodiments, are described in detail below with reference to the accompanying drawings.

Description of drawings

Figure 1 shows a schematic, not-to-scale view of an overall broad concept of a laser-produced plasma EUV light source system according to one aspect of the embodiments.

2 is a plan view of a droplet dispenser that may be used in an EUV light source such as that shown in FIG. 1 .

3 is a conceptual diagram of a source material supply system having a plurality of source material chambers.

4A is a plan view of internal components for a source material valve according to an aspect of an embodiment.

Figure 4B is a bottom view of the internal components of Figure 4A.

5 is a plan view of an alternate configuration of internal components for a source material valve according to an aspect of an embodiment.

6 is a cross-sectional view of a source material valve in a first state according to an aspect of an embodiment.

7 is a cross-sectional view of the source material valve of FIG. 6 in a second state.

8 is a schematic diagram of a multi-chamber system in which source material valves establish unidirectional flow, according to an aspect of an embodiment.

Other features and advantages of the present invention, as well as the structure and operation of various embodiments of the present invention are described in detail below with reference to the accompanying drawings. It should be noted that the present invention is not limited to the specific embodiments described herein. Such examples are presented herein for illustrative purposes only. Other embodiments will be apparent to persons skilled in the relevant art(s) based on the teachings contained herein.

Detailed ways

Various embodiments are now described with reference to the drawings, wherein like reference numerals are used to refer to like elements throughout. In the following description, for purposes of explanation, numerous specific details are set forth in order to facilitate a thorough understanding of one or more embodiments. It should be evident, however, that in some or all cases any of the embodiments described below may be practiced without employing the specific design details described below.

Referring first to FIG. 1 , there is shown a schematic diagram of an exemplary EUV light source, such as a laser-produced plasma EUV light source 20 , in accordance with an aspect of an embodiment of the present invention. As shown, EUV light source 20 may include a pulsed or continuous laser source 22, which may be, for example, a pulsed fluid discharge CO2 laser source producing radiation at 10.6 μm or other suitable wavelength. Pulsed fluid discharge CO2 laser sources can have DC or RF excitation operating at high power and high pulse repetition rate.

The EUV light source 20 also includes a source delivery system 24 for delivering the source material in the form of droplets or a continuous stream. The source material can be made of tin or tin compounds, but other materials can also be used. Source delivery system 24 introduces the source material into the interior of chamber 26 to an irradiation region 28 where the source material may be irradiated to generate a plasma. In some cases, charges are placed on the source material to permit the source material to be directed toward or away from the illuminated region 28 . It should be noted that, as used herein, an illuminated area is an area where illumination of source material can occur and is an illuminated area even when illumination does not actually occur.

Continuing with FIG. 1 , light source 20 may also include one or more optical elements, such as collector 30 . Collector 30 may be a normal incidence reflector, for example, implemented as a multilayer mirror or "MLM", that is, a SiC substrate coated with Mo/Si multilayers, deposited at each interface with additional Thin barrier layers to effectively block thermally induced interlayer diffusion. Other substrate materials, such as aluminum or silicon, may also be used. The collector 30 may be in the form of an oblong, with holes allowing the laser light to pass through and reach the irradiation area 28 . The collector 30 may be, for example, in the shape of an ellipsoid with a first focus at the irradiation area 28 and a second focus at a so-called intermediate point 40 (also referred to as an intermediate focus), where EUV light may be output from the EUV light source 20 and input To, for example, an integrated circuit lithography tool 50 which uses the light to process, for example, a silicon wafer workpiece 52 in a known manner. The silicon wafer workpiece 52 is then additionally processed in a known manner to obtain integrated circuit devices.

The EUV light source 20 may also include an EUV light source controller system 60 which may also include a laser emission control system 65 together with eg a laser beam positioning system (not shown). The EUV light source 20 may also include a source position detection system, which may include one or more droplet imagers 70 that generate an output indicative of the absolute or relative position of the source droplet ( eg absolute or relative position relative to the illumination area 28 ) and this output is provided to the source position detection feedback system 62 . The source position detection feedback system 62 can use this output to calculate the source position and trajectory, from which the source error can be calculated. The source error may then be provided as input to the light source controller 60 . In response, light source controller 60 may generate a control signal (such as a laser position, direction or timing correction signal) and provide this control signal to a laser beam positioning controller (not shown). The laser beam positioning system may use the control signals to control the laser timing circuitry and/or control the laser beam position and shaping system (not shown), for example, to vary the position of the laser beam focus within chamber 26 and/or focus power.

As shown in FIG. 1 , light source 20 may include a source delivery control system 90 . Source delivery control system 90 is operable in response to a signal (e.g., the source error described above, or some quantity derived from the source error provided by system controller 60) to correct the position of the source droplet within irradiation region 28 error. This can be achieved, for example, by repositioning the point at which the source delivery mechanism 92 releases the source droplet. The source delivery mechanism 92 extends into the chamber 26 and is also externally supplied with source material and a source of fluid to place the source material in the source delivery mechanism 92 under pressure.

FIG. 2 shows source delivery mechanism 92 for delivering source material into chamber 26 in greater detail. For the generalized embodiment shown in FIG. 2 , source delivery mechanism 92 may include a reservoir 94 that holds molten source material, such as tin. A heating element (not shown) controllably maintains the source delivery mechanism 92, or a selected section thereof, at a temperature above the melting temperature of the source material. Molten source material 95 may be brought under pressure using an inert fluid, such as argon, introduced through supply line 96 . The pressure forces source material 95 through supply conduit 98 which delivers molten source material to valve 100 and nozzle 102 . Supply conduit 98 is heated and may include one or more filters. Conventionally, as noted above, this supply conduit 98 may be made of tantalum tungsten alloy and is connected to other components in the system by compression fittings, which may be made of molybdenum, to maintain a fluid-tight seal. Supply conduit line 98 is preferably flexible to permit relative movement of reservoir 94 and nozzle 102 .

Valve 100 may be a thermal valve. The valve 100 may be constructed using a thermoelectric device such as a Peltier device: freezing the source material between the reservoir 94 and the nozzle 102 to close the valve 100 and heating the solidified source material to open the valve 100 . FIG. 2 also shows that source delivery mechanism 92 is coupled to movable member 104 such that movement of movable member 104 changes the location of the point at which droplets are released from nozzle 102 . Movement of the movable member 104 is controlled by a droplet release point positioning system.

For source delivery mechanism 92, one or more modulating or non-modulating source material dispensers may be used. For example, a brewing dispenser having a capillary formed with an orifice can be used. Nozzle 102 may include one or more electrically actuated elements (such as actuators made of piezoelectric material) that may be selectively expanded or contracted to deform the capillary and condition the source material release from the nozzle 102.

For some applications, it would be potentially advantageous to provide an online drop generator refill system and procedure that does not require shutting down the system to refill the reservoir and then bringing the system back online. Therefore, this online refill system is able to refill tin without stopping droplet generation, greatly increasing the overall system availability. Such systems may use multiple source material chambers, such as a main reservoir, a refill reservoir, a refill tank, and a priming tank. An example of a two-chamber system comprising a reservoir and a container is disclosed in U.S. Patent No. 8,816,305, entitled "Filter for Material Supply Apparatus" issued August 26, 2014, The entire disclosure content thereof is incorporated herein by reference. The transfer of tin between these reservoirs was driven by applying different pressures to the chambers. Molten tin reacts strongly to differential pressure. A pressure difference of 1psi will result in a tin height difference of 100mm. Typically, droplet generators operate at a pressure of about 4000 psi. Here and elsewhere, the term "fluid" is used in its conventional sense, referring to both gases and liquids.

When refilling tin while the droplet generator is operating, any of several failures may allow molten tin to enter the fluid inlet line. For example, pressure control failures, data communication errors, or incorrect calibration or drift of pressure controllers can cause liquid lines to become flooded with liquid tin. Because there is no heating mechanism in the fluid line, the liquid tin can freeze and severely clog the fluid line. Fixing this issue may require extended downtime, or even module replacement.

One method of attempting to reduce the likelihood of tin clogging fluid supply lines involves the use of interlock devices to protect the fluid lines. However, these interlocks can greatly increase the complexity of the system. They can also cause inadvertent depressurization of in-line refill systems. They also do not fully prevent fluid line contamination due to, for example, pressure sensor drift or software errors, or simple communication errors or delays.

According to an aspect of the embodiments, by interposing a source material valve between the source material path and the fluid line, a more reliable and robust system for preventing source material from entering the fluid supply line is provided. Such measures are basically error-proof in principle and robust against all failures caused by errors such as software/hardware failures, network communication errors, power outages, sensor drift, etc. Such systems also simplify machine and material damage control design, thereby increasing overall system availability and robustness.

Figure 3 is a conceptual diagram of such a system. FIG. 3 shows two chambers for holding molten source material, a main reservoir 300 and a refill reservoir 310 . Main reservoir 300 includes liquid source material 305 and refill reservoir 310 includes liquid source material 315 . Main reservoir 300 is pressurized with fluid from fluid supply line 307 . Refill reservoir 310 is pressurized by fluid from fluid supply line 317 . The fluid may be any suitable inert fluid, such as argon. Typically, main storage 300 and refill storage 310 are pressurized to a pressure of about 4000 psi.

In a typical conventional system, there is nothing to prevent the source material in the chamber from rising up, filling the chamber, and reaching the fluid supply line, causing all of the problems described above. According to one aspect of an embodiment, a liquid source material valve is used to prevent source material from entering the fluid fill line. In particular, source material valve 320 is placed between chamber 300 and fluid supply line 307 . Source material valve 320 is in fluid communication with chamber 300 . Fluid communication herein means that there is a path between the source material valve 320 and the chamber 300 through which fluid can flow. Conceptually, this can be equivalently viewed as placing source material valve 320 in fluid line 307 . Furthermore, a source material valve 330 is placed between the chamber 310 and the fluid supply line 317 . Each source material valve allows free flow of fluid in both directions, even with pressure differentials, as long as there is no incoming source material flow. However, if the source material 305 ascends and enters the source material valve 320, the source material valve 320 will close. Similarly, if source material 315 ascends and enters source material valve 330, source material valve 330 will close.

According to one aspect of the embodiment, the source material valve includes a valve body defining an internal cavity and an internal component occupying a normal operating position within the cavity in which fluid flows through the valve (first state) , but the internal component can be moved by the source material entering the cavity to a second position in which the fluid line entering the cavity is sealed (second state). In particular, referring to FIG. 4A , there is shown an internal component 400 designed to move within a cavity as described below. The inner component 400 has a body 405 with a gap 417 that permits fluid to pass through the inner component. The body 405 may be generally cylindrical with wings 410 disposed about the lower periphery of the body 405 to establish clearance and help stabilize the position of the inner component 400 within the cavity. Alternatively, wings 410 are referred to as fins or spacer elements, the latter because they help maintain the separation between body 405 and the cavity walls in the source material valve in which internal component 400 is positioned . In general, there are preferably at least three airfoil members 410 arranged in a rotationally symmetric pattern about the lower perimeter of the generally cylindrical body 405 (that is, with respect to the rotation of the generally cylindrical body 405 Axisymmetric). In the arrangement shown, there are six wings 410 spaced 60 degrees apart around the lower perimeter of the generally cylindrical body 405, although those of ordinary skill in the art will readily appreciate that a different number of wings may be used and that the wings may be arranged in Different pattern arrangements. The outer sides 415 of the wings 410 may be provided with rounded edges in all directions to prevent clogging. FIG. 4B is a bottom view of the inner component 400 of FIG. 4A showing the orientation of the wings 410 . FIG. 5 shows an inner component 450 having another possible configuration in which the bottom of the component body 455 is tapered to facilitate passage of fluid through the inner component. The wings 410 are shaped and spaced such that there is a space or void between them, allowing fluid to flow freely through the cylinder 405 and through the spaces between the wings 410 as long as there is no incoming source material flow.

FIG. 6 is a cross-sectional view of a source material valve 320 according to an aspect of an embodiment. The source material valve 320 includes a valve body 500 defining a cavity 510 therein. Internal component 400 is positioned within cavity 510 . In the position shown in FIG. 6 , the inner part 400 is placed on the bottom of the cavity 510 . This would be the normal operating position or first state when there is no source material surge in which fluid flows in from fluid supply line 307 through cavity 510 and then exits through the bottom of cavity 510 . Also shown in FIG. 6 is heater 530 which is in thermal contact with valve body 500 and which heats source material valve 320 to a temperature above the melting point of the source material.

For some embodiments, the cavity 510 has a substantially uniform width and the inner component body 405 has a width that is less than the cavity width to create a gap between the cavity walls and the inner component through which fluid can flow. This gap is maintained by wings 410 acting as spacing elements adapted to keep the body 405 laterally spaced from the walls of the cavity 510 . As described above, the spacer element may comprise at least one pair of protrusions extending laterally from the body 405 in opposite directions, the protrusions having a transverse width such that the width of the protrusions together with the body width is just slightly less than the cavity width. In some embodiments, cavity 510 is cylindrical with a first diameter and body 405 is cylindrical with a second diameter smaller than the first diameter. The spacer element, ie the wing 410 may be an airfoil member extending radially from the main body.

7 is a cross-sectional view of the source material valve 320 of FIG. 6 in a second state in which the inner component 400 has been pushed into the cavity by the molten source material 540 when there is a surge of tin flow due to a pressure change. 510 top. In this position, the tin 540 is prevented from moving further into the cavity 510 and out into the fluid supply line 307 attached to the top of the source material valve 320 . The top of the inner part 400 and the top of the cavity 510 are in contact to seal the surfaces so no source material can pass through to the fluid line 307 .

Referring again to FIG. 6 , the inner component 400 includes a body configured to seat itself against the top of the cavity 510 to seal the top of the cavity 510 . The inner part 400 also has wings or fins 410 that hold the inner part 400 in the correct orientation and permit fluid flow through the inner part 400 .

According to one aspect of the embodiment, in use, the source material valve 320 is oriented vertically and the inner part 400 is preferably configured to be buoyant with respect to the molten source material. This can be achieved by making the inner part 400 have an interior volume or by making the inner part solid and made of a material that is lighter than the molten source material. The inner component 400 is also preferably made of a material that is chemically and thermally stable in the presence of the liquid source material and has mechanical strength at a prevailing pressure of, for example, 4000 psi. In the example where the source material is tin, the body 405 of the inner component 400 may be made of, for example, titanium or a titanium alloy such as Ti-Mn or Ti-V, although other suitable materials may be used in other embodiments. The material used for the wings 410 should have the same chemical and mechanical stability against the liquid tin environment as the body 405 and may in some embodiments be formed from the same material as the body 405 . Because the wings 410 constitute a relatively small portion of the combined volume of the wings 410 and body 405, the wings 410 may be made of heavier materials of sufficient strength, such as titanium, molybdenum, tungsten, and their alloys, but in other embodiments other materials may be used. suitable material. The inner surface of the cavity 510 of the valve body 500 is preferably made of a material that is chemically and thermally stable in the presence of the liquid source material, such as molybdenum if the source material is tin, but in other embodiments may be used. other suitable materials.

According to another aspect of the embodiment, the top surface of the inner component 400 is a portion of the surface of a sphere having a radius R. As shown in FIG. This is referred to herein as a "spherical" surface. The upper wall of cavity 510 has a complementary spherical surface of radius R. Matching the curvature of the two mating surfaces in this way allows a good seal to be formed even when the inner part 400 is not perfectly vertical.

According to another aspect of the embodiment, the diameter of the main portion of the inner part 400 , designated D2 in FIG. 6 , is made larger than the diameter D4 of the hole at the top of the cavity 510 . This enables a good seal even if the inner part 400 is not perfectly vertical.

According to another aspect of the embodiment, the width between the outboard edges of opposing wings 410, the "wingspan" designated D1 in FIG. 6, is set to be slightly smaller than cavity 510, designated D3 in FIG. diameter of. The vertical extent of wings 410 is chosen to prevent inner component 400 from tipping over and becoming lodged in cavity 510 . D1 may be considered as the largest outer diameter of the inner part 400 including the gap 417 between the outermost portions formed by the wings 410 .

As some non-limiting examples of dimensions, D4 can be made equal to a typical fluid line ID of 0.25 inches. D3 can be made about twice that of D4, ie 0.5 inches. D2 may be (√3)/4 inches to make the fluid channel cross section consistent along the length of cavity 510 . D1 is preferably slightly smaller than D3, for example 0.04 inches shorter than D3. R can range from 10 inches to 40 inches. The height of the interior member 400, designated H2, may generally be in the range of 1 to 2 inches. The height difference between H1 and H2 is preferably less than 0.5 inches, and more preferably less than 0.25 inches. These are only examples of dimensions and it will be apparent to one of ordinary skill in the art that other dimensions may be used.

As noted above, in a multi-chamber system, it may be desirable to have a unidirectional flow of molten source material from a first chamber to a second chamber, with flow from the second chamber back to the first chamber not permitted. This may be the case, for example, when a first chamber comprises purified molten source material and a second chamber comprises contaminated or less pure molten source material. In such arrangements, source material valves may also be used to advantage. For example, in FIG. 8 , first reservoir 800 includes substantially pure source material 805 . The second reservoir 810 includes a less pure source material 815 . There may be situations where it is desirable to permit flow from the first chamber 800 to the second chamber 810 but not reverse flow. To accommodate these situations, a source material valve 820 may be inserted between the two chambers. The source material 805 will have substantially the same density as the source material 815, so the internal components 825 in the source material valve 820 will tend to be neutrally buoyant. However, in the event of a failure causing the pressure in chamber 810 to be higher than the pressure in chamber 800, inner part 825 shaped like inner part 400 in FIGS. presents greater flow resistance and will tend to move against the top of chamber 830, blocking flow.

Although the above description is in relation to the use of the novel source material valve in an apparatus for supplying source material in an EUV source, those of ordinary skill in the art will readily appreciate that the principles disclosed herein can also be advantageously applied to applications where flow of molten material needs to be prevented. in other applications.

The above description includes examples of various embodiments. It is, of course, not possible to describe every possible combination of components or methodologies for purposes of describing the above-described embodiments, but one of ordinary skill in the art may recognize that many further combinations and permutations of various embodiments are possible. Accordingly, the described embodiments are intended to embrace all such alterations, modifications and variations that fall within the spirit and scope of the appended claims. Furthermore, to the extent that the term "comprises" is used in the detailed description or in the claims, the term is intended to encompass in a manner similar to how the term "comprises" such as "comprises" is interpreted when used as a transitional word in the claims. Furthermore, although elements of the described aspects and/or embodiments may be described or claimed in the singular, the plural is contemplated unless limitation to the singular is expressly stated. Additionally, 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, unless stated otherwise.

Other aspects of the invention are set forth in the following numbered clauses.

1. An apparatus for controlling the flow of molten source material from a source material holding chamber in an EUV source, the apparatus comprising:

a valve body defining a cavity having a first valve body end adapted to be connected to a fluid supply line and a second valve body end adapted to be in fluid communication with the source material holding chamber, the cavity being closer to the first a body end having a seat wall at its end; and

an inner member disposed in the cavity and adapted to move from a first position in which the inner member permits fluid flow through the cavity to a second position in which the upper portion of the inner member sits against Seat walls to prevent molten source material from flowing through the cavity.

2. The device of clause 1, wherein the cavity has a substantially uniform cavity width, and wherein the inner part comprises a body having a body width less than the cavity width, and a body adapted to hold the body in contact with the cavity. A plurality of spacer elements are laterally spaced apart from the sidewall.

3. The device of clause 2, wherein the spacing element comprises at least one pair of protrusions extending laterally from the body in opposite directions, the protrusions having a lateral width such that the width of the protrusions together with the body width is smaller than the cavity width.

4. The device of clause 2, wherein the cavity is cylindrical with a first diameter and the body is cylindrical with a second diameter smaller than the first diameter.

5. The device of clause 4, wherein the spacer element is an airfoil member extending radially from the main body.

6. The device of clause 1, wherein the inner part comprises a generally cylindrical body and a plurality of airfoil members extending radially outward from the main body and surrounding a lower perimeter of the generally cylindrical body furnished.

7. The device according to clause 6, wherein the plurality of airfoil members comprises at least three airfoil members arranged in a rotationally symmetrical pattern around the lower periphery of the generally cylindrical body .

8. The device of clause 7, wherein the plurality of airfoil members comprises six airfoil members arranged at 60 degree intervals around the lower perimeter of the generally cylindrical body.

9. The device of clause 6, wherein the outer face of each of the airfoil members is circular.

10. The device of clause 1, wherein the internal component is solid and comprises a material having a density less than that of the molten source material.

11. The device of clause 2, wherein the body is solid and comprises a material having a density less than that of the molten source material.

12. The device of clause 2, wherein the internal component comprises titanium or a titanium alloy.

13. The device of clause 2, wherein each of the spacer elements comprises titanium, molybdenum, tungsten, or alloys thereof.

14. The device of clause 1, wherein the inner member has a spherical upper surface of radius R and wherein the seat wall has a complementary spherical surface of radius R.

15. The device of clause 1, wherein the inner part has a tapered lower portion.

16. The device of clause 1, further comprising a heater in thermal contact with the valve body and adapted to maintain the temperature of the valve body and internal components above the melting point of the source material.

17. The device of clause 1, wherein an inner surface of the cavity comprises molybdenum.

18. An apparatus for controlling the flow of molten source material from a chamber in an EUV source, the apparatus comprising:

A valve body defining a vertical cavity when vertically arranged, the valve body having an upper valve body end adapted to be connected to a fluid supply line and a lower valve body end adapted to be in fluid communication with the chamber, the cavity in the cavity The upper end of the chamber has a seat wall; and

an inner member disposed in the cavity and adapted to be moved vertically by molten source material entering the cavity through the lower valve body end from a first position to a second position in which the inner member permits Fluid flows through the cavity, and in the second position, the upper portion of the inner part moves towards the seat wall and makes sealing contact against the seat wall to prevent molten source material from flowing through the cavity.

19. Apparatus according to clause 18, wherein the inner part comprises a generally cylindrical body and a plurality of airfoil members extending radially outward from the generally cylindrical body and arranged to surround the generally cylindrical body The lower perimeter of the upper cylindrical body.

20. The device of clause 19, wherein the plurality of airfoil members comprises at least three airfoil members arranged in a rotationally symmetric pattern around the lower portion of the generally cylindrical body. around.

21. The device of clause 20, wherein the plurality of airfoil members comprises six airfoil members arranged at 60 degree intervals around the lower perimeter of the generally cylindrical body.

22. Apparatus according to clause 20, wherein the outer face of each of the airfoil members is rounded.

23. The device of clause 18, wherein the internal component is solid and comprises a material having a density less than that of the molten source material.

24. The device of clause 18, wherein the internal component comprises titanium or a titanium alloy.

25. The device of clause 18, wherein the inner member has a spherical upper surface of radius R and wherein the seat wall has a complementary spherical surface of radius R.

26. The apparatus of clause 18, further comprising a heater in thermal contact with the valve body and adapted to maintain the temperature of the valve body and internal components above the melting point of the source material.

27. An apparatus for controlling the flow of molten source material from a chamber in an EUV source, the apparatus comprising:

a valve body defining a cavity having a first valve body end adapted to be connected to a fluid supply line and a second valve body end adapted to be placed in fluid communication with the chamber, the cavity being closer to the valve having a seat wall at the end of the body end; and

internal components, are arranged in the cavity,

The device is adapted to have a first state in which the internal component permits fluid flow through the cavity, and a second state in which the cavity is at least partially filled with molten source material and in the second state , due to the molten source material in the cavity, the internal component prevents the molten source material from flowing through the cavity.

28. An apparatus for controlling flow of molten source material between a first source material holding chamber and a second source material holding chamber in an EUV source, the apparatus comprising:

A valve body defining a cavity, the valve body having a first valve body end adapted to be in fluid communication with the attached first source material holding chamber and a second valve body adapted to be in fluid communication with the second source material holding chamber end, the cavity has a seat wall at an end closer to the first valve body end; and

an inner member disposed in the cavity and adapted to move between a first position and a second position in which the inner member allows source material to flow through the cavity from the first source material holding chamber to the second The source material holding chamber, in the second position, the upper portion of the inner member is seated against the seat wall to prevent molten source material from flowing through the cavity from the second source material holding chamber to the first source material holding chamber.

29. The device of clause 28, wherein the inner part comprises a generally cylindrical body and a plurality of airfoil members arranged around a lower perimeter of the generally cylindrical body.

30. The device according to clause 29, wherein the plurality of airfoil members comprises at least three airfoil members arranged in a rotationally symmetric pattern around the lower portion of the generally cylindrical body. around.

31. The device of clause 30, wherein the plurality of airfoil members comprises six airfoil members arranged at 60 degree intervals around the lower perimeter of the generally cylindrical body.

32. The device of clause 29, wherein the outer face of each of the airfoil members is rounded.

33. The device of clause 28, wherein the internal component comprises titanium or a titanium alloy.

34. The device of clause 28, wherein the inner member has a spherical upper surface of radius R and wherein the seat wall has a complementary spherical surface of radius R.

35. The device of clause 28, further comprising a heater in thermal contact with the valve body and adapted to maintain the temperature of the valve body and internal components above the melting point of the source material.

36. The device of clause 28, wherein an inner surface of the cavity comprises molybdenum.

The implementations described above and other implementations are within the scope of the following claims.

Claims (36)

1. An apparatus for controlling the flow of molten source material from a source material holding chamber in an EUV source, said apparatus comprising: a valve body defining a cavity, the valve body having a first valve body end adapted to be connected to a fluid supply line and a second valve body end adapted to be placed in fluid communication with the source material holding chamber, the said cavity has a seat wall at an end closer to said first valve body end; and an inner member disposed within the cavity and adapted to move from a first position in which the inner member permits fluid flow through the cavity to a second position in which the inner member permits fluid flow through the cavity and in the second position position, the upper portion of the inner part sits against the seat wall to prevent molten source material from flowing through the cavity. 2. The device of claim 1, wherein the cavity has a substantially uniform cavity width, and wherein the inner part comprises a body and a plurality of spacer elements, the body having a width less than the cavity width. The width of the body, the plurality of spacer elements are adapted to maintain the body laterally spaced from the sidewall of the cavity. 3. The device of claim 2, wherein the spacing element comprises at least one pair of protrusions extending laterally from the body in opposite directions, the protrusions having a transverse width such that the width of the protrusions is the same as the width of the protrusions. The width of the body is together smaller than the width of the cavity. 4. The device of claim 2, wherein the cavity is cylindrical with a first diameter and the body is cylindrical with a second diameter, the second diameter being smaller than the first diameter. 5. The device of claim 4, wherein the spacer element is an airfoil member extending radially from the body. 6. The device of claim 1, wherein the inner part comprises a generally cylindrical body and a plurality of airfoil members extending radially outward from the body and arranged as surrounding the lower perimeter of the generally cylindrical body. 7. The apparatus of claim 6, wherein the plurality of airfoil members comprises at least three airfoil members arranged in a rotationally symmetric pattern around the generally cylindrical The lower periphery of the main body. 8. The apparatus of claim 7, wherein the plurality of airfoil members comprises six airfoil members arranged at 60 degree intervals around the generally cylindrical body the lower perimeter. 9. The apparatus of claim 6, wherein an outer side of each of the airfoil members is rounded. 10. The apparatus of claim 1, wherein the internal component is solid and comprises a material having a density less than that of the molten source material. 11. The apparatus of claim 2, wherein the body is solid and comprises a material having a density less than that of the molten source material. 12. The device of claim 2, wherein the internal component comprises titanium or a titanium alloy. 13. The device of claim 2, wherein each of the spacer elements comprises titanium, molybdenum, tungsten, or alloys thereof. 14. The device of claim 1, wherein the inner member has a spherical upper surface of radius R and wherein the seat wall has a complementary spherical surface of radius R. 15. The device of claim 1, wherein the inner member has a tapered lower portion. 16. The apparatus of claim 1, further comprising a heater in thermal contact with the valve body and adapted to maintain the temperature of the valve body and the internal components at the melting point of the source material above. 17. The device of claim 1, wherein an inner surface of the cavity comprises molybdenum. 18. An apparatus for controlling the flow of molten source material from a chamber in an EUV source, the apparatus comprising: a valve body defining a vertical cavity when vertically arranged, the valve body having an upper valve body end adapted to be connected to a fluid supply line and a lower valve adapted to be placed in fluid communication with the chamber a body end, the cavity having a seat wall at an upper end of the cavity; and an inner component disposed in the cavity and adapted to be moved vertically from a first position to a second position by molten source material entering the cavity through the lower valve body end at the first position, the inner member permits fluid flow through the cavity, and in the second position, the upper portion of the inner member moves toward and makes sealing contact against the seat wall to prevent melting of the source material flow through the cavity. 19. The device of claim 18, wherein the inner part comprises a generally cylindrical body and a plurality of airfoil members radially outward from the generally cylindrical body extends and is arranged around a lower perimeter of the generally cylindrical body. 20. The apparatus of claim 19, wherein the plurality of airfoil members comprises at least three airfoil members arranged in a rotationally symmetric pattern around the generally cylindrical The lower periphery of the main body. 21. The apparatus of claim 20, wherein the plurality of airfoil members comprises six airfoil members arranged at 60 degree intervals around the generally cylindrical body the lower perimeter. 22. The apparatus of claim 20, wherein the outer side of each of the airfoil members is rounded. 23. The apparatus of claim 18, wherein the internal component is solid and comprises a material having a density less than that of the molten source material. 24. The device of claim 18, wherein the internal component comprises titanium or a titanium alloy. 25. The device of claim 18, wherein the inner member has a spherical upper surface of radius R and wherein the seat wall has a complementary spherical surface of radius R. 26. The apparatus of claim 18, further comprising a heater in thermal contact with the valve body and adapted to maintain the temperature of the valve body and the internal components at the melting point of the source material above. 27. An apparatus for controlling the flow of molten source material from a chamber in an EUV source, the apparatus comprising: a valve body defining a cavity having a first valve body end adapted to be connected to a fluid supply line and a second valve body end adapted to be placed in fluid communication with the chamber, the cavity having a seat wall at an end closer to the valve body end; and internal components, are arranged in the cavity, The device is adapted to have a first state in which the internal component permits fluid flow through the cavity and a second state in which the cavity is at least partially Filled with molten source material and in a second state, the inner component prevents flow of the molten source material through the cavity due to the molten source material in the cavity. 28. An apparatus for controlling flow of molten source material between a first source material holding chamber and a second source material holding chamber in an EUV source, the apparatus comprising: a valve body defining a cavity, the valve body having a first valve body end adapted to be placed in fluid communication with the connected first source material holding chamber and adapted to be placed in fluid communication with the second source material a second valve body end of material holding a chamber in fluid communication, the cavity having a seat wall at an end closer to the first valve body end; and an internal component disposed within the cavity and adapted to move between a first position and a second position: In said first position, said inner member allows source material to flow through said cavity from said first source material holding chamber to said second source material holding chamber, In the second position, the upper portion of the inner part is seated against the seat wall to prevent molten source material from flowing through the cavity from the second source material holding chamber to the first source Material holding chamber. 29. The device of claim 28, wherein the internal component comprises a generally cylindrical body and a plurality of airfoil members arranged to surround the circumference of the generally cylindrical body. Lower perimeter. 30. The apparatus of claim 29, wherein the plurality of airfoil members comprises at least three airfoil members arranged in a rotationally symmetric pattern around the generally cylindrical The lower periphery of the main body. 31. The apparatus of claim 30, wherein the plurality of airfoil members comprises six airfoil members arranged at 60 degree intervals around the generally cylindrical body the lower perimeter. 32. The apparatus of claim 29, wherein an outer side of each of the airfoil members is rounded. 33. The device of claim 28, wherein the internal component comprises titanium or a titanium alloy. 34. The device of claim 28, wherein the inner member has a spherical upper surface of radius R and wherein the seat wall has a complementary spherical surface of radius R. 35. The apparatus of claim 28, further comprising a heater in thermal contact with the valve body and adapted to maintain the temperature of the valve body and the internal components at the melting point of the source material above. 36. The device of claim 28, wherein an inner surface of the cavity comprises molybdenum.

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