Gas flow apparatus and method for EUV light source

Abstract

A liner for a radiation source container for generating extreme ultraviolet (EUV) light includes a wall having an inner surface. The inner surface extends from the collector end toward the intermediate focal end. The inner surface has an exhaust opening that penetrates the inner surface and begins at a distance D along the inner surface from the collector end toward the intermediate focal end. Each gas inlet is located at various positions from near the collector end toward the distance D along the inner surface. At least some of the gas inlets are configured to supply a gas flow rate that varies depending on the position along the distance D in order to reduce deposition on the inner surface. A process or method for operating the EUV light source is also disclosed.

Description

Technical Field

[0001] (Cross - reference to Related Applications)

[0001] This application claims priority to U.S. Patent Application No. 63 / 493,060, entitled "GAS FLOW APPARATUS AND METHOD FOR EUV LIGHT SOURCE", filed on March 30, 2023; U.S. Patent Application No. 63 / 627,878, entitled "GAS FLOW APPARATUS AND METHOD FOR EUV LIGHT SOURCE", filed on February 1, 2024; and U.S. Patent Application No. 63 / 555,572, entitled "GAS FLOW APPARATUS AND METHOD FOR EUV LIGHT SOURCE", filed on February 20, 2024. These applications are hereby incorporated by reference in their entirety.

[0002]

[0002] The present disclosure relates to an apparatus and method for controlling the flow of products generated by irradiation of a target within a radiation source vessel for generating extreme ultraviolet ( "EUV") radiation within the vessel, and more particularly, to an apparatus and method for providing a gas flow within the vessel to assist in guiding or controlling such product flow.

Background Art

[0003]

[0003] For example, extreme ultraviolet radiation, such as electromagnetic radiation having wavelengths of about 50 nm or less (sometimes also called soft X-rays), including radiation with a wavelength of about 13.5 nm, can be used in photolithography processes for semiconductor manufacturing or inspection processes for quality control. Methods for generating EUV radiation include converting a target material into a plasma state. The target material contains at least one element having one or more emission lines in the EUV portion of its electromagnetic spectrum, such as xenon, lithium, or tin. The target material may be a solid, liquid, or gas. One such method, often called laser-generated plasma ("LPP"), can generate the desired plasma by irradiating a target containing one or more EUV-emitting elements with one or more light pulses using a "source" laser, which is typically a CO2 laser emitting infrared light with a wavelength of around 10,600 nanometers (nm). The plasma is usually generated in a sealed "radiation source container," which is typically a vacuum chamber.

[0004]

[0004] When plasma is generated from the target material inside the radiation source container, vapor, ions, particulate matter, and other debris are generated, which can accumulate on surfaces inside the radiation source container, including optical surfaces, and contaminate the surfaces. Therefore, it is necessary to remove one or more residual target materials from the radiation source container to reduce or eliminate surface contamination inside the radiation source container. [Overview of the project]

[0005]

[0005] In some common embodiments, liners are provided for radiation source containers for generating extreme ultraviolet (EUV) light. The liner includes a wall having an inner surface, the inner surface extending from a collector end of the inner surface toward an intermediate focal end of the inner surface, and the inner surface having a discharge opening extending through the inner surface, the discharge opening beginning at a distance along the inner surface toward the intermediate focal end, and gas inlets positioned at each location from near the collector end toward a distance along the inner surface. At least some of the gas inlets are configured to supply a gas flow rate that varies depending on each location along the distance.

[0006]

[0006] The embodiments may include one or more of the following:

[0007]

[0007] The gas inlets may be configured to guide the debris flow starting near the primary focal point and toward the discharge opening. A gas inlet located in a first elongated area on the inner surface of the liner may provide a flow rate that increases along the direction extending from the collector end, and a gas inlet located in a second elongated area on the inner surface of the liner may provide a flow rate that decreases along the direction extending from the collector end. The second elongated area may extend from near the collector end to near the nearest edge of the discharge opening, and the first elongated area may extend from near the collector end to near the opposite side of the nearest edge of the discharge opening.

[0008]

[0008] The volume inside the liner has a cross-section that decreases as it approaches the intermediate focal point from the collector end, and the second elongated area may be positioned on the opposite side of the first elongated area. The inside of the liner has a conical shape with a circular cross-section, and the cross-section decreases as it approaches the intermediate focal point from the collector end, and the second elongated area may be positioned on the opposite side of the first elongated area.

[0009]

[0009] The gas inlets are configured to supply a gas flow rate that increases in stages along a distance in a first elongated area, with each stage comprising two or more gas inlets. The gas inlets may be configured to supply a gas flow rate that increases nonlinearly along a distance in a first elongated area, with each stage comprising two or more gas inlets. At least some gas inlets may have flow limits that vary depending on their respective positions. At least some gas inlets may be in the form of holes of different diameters that penetrate the wall of the liner. At least some gas inlets may be in the form of holes that penetrate the wall of the liner, to which flow limiters having different limits may be connected. At least some of the gas inlets may be supplied in groups of two or more by each of two or more flow controllers, with the two or more flow controllers being configured to supply flow at different flow rates according to each position in each group.

[0010]

[0010] The liner further includes a plurality of gas supply plenums, and each gas inlet may be connected to one of the plurality of gas supply plenums. Each of the plurality of gas supply plenums may be supplied by each flow controller. Each gas inlet may direct flow in each major flow direction at a 90-degree angle with respect to the inner surface at each location of the gas inlet. The gas inlets may direct flow in each major flow direction at different angles with respect to the inner surface at each location of the gas inlet. The gas inlets may direct flow in each flow direction that varies from approximately 90 degrees with respect to the inner surface at each location of the gas inlet as the distance from the collector end increases.

[0011]

[0011] In an additional general embodiment, a method for operating an extreme ultraviolet (EUV) light source is provided. The method includes flowing gas from inlets located at various positions along the inner surface of a radiation source container, the inner surface extending from the collector end of the inner surface toward the intermediate focal end of the inner surface; flowing gas from inlets located in a first elongated area on the inner surface at a flow rate that increases with distance from the collector end; and flowing gas from inlets located in a second elongated area on the inner surface at a flow rate that decreases with distance from the collector end. The second elongated area extends from near the collector end toward the nearest edge of the discharge opening on the inner surface, and the first elongated area extends from near the collector end toward or toward the opposite side of the nearest edge of the discharge opening.

[0012]

[0012] The embodiments may include one or more of the following:

[0013]

[0013] Flowing gas at an increasing flow rate may include using a first set of flow controllers connected to inlets located within a first elongated area. Flowing gas at a decreasing flow rate may include using a second set of flow controllers connected to inlets located within a second elongated area. Flowing gas at a decreasing flow rate may include using flow limiters located at or connected to inlets within the first elongated area, with the limit increasing in proportion to the distance of these inlets from the collector end. Flowing gas at an increasing flow rate may include using flow limiters located at or connected to inlets, with the limit decreasing in proportion to the distance of these inlets from the collector end.

[0014]

[0014] In a more general embodiment, a method for operating an extreme ultraviolet (EUV) light source is provided. The method includes flowing a gas into the radiation source container of the EUV light source and generating pressure oscillations having a frequency in the range of 40 Hz to 40 kHz within the flowing gas.

[0015]

[0015] The embodiments may include one or more of the following:

[0016]

[0016] Generating pressure oscillations in a flowing gas may include generating oscillations in an oscillator that is in direct or indirect contact with the flowing gas. The oscillator may be connected to a coil that is connected to a supply of fluctuating current and positioned in a magnetic field. Flowing the gas may include flowing a forward flow of gas. Flowing the gas may include flowing gas from inlets located at various positions along the inner surface of the radiation source container, the inner surface may extend from the inner surface collector end toward the inner surface intermediate focal end. Flowing the gas may include changing the flow rate, and generating pressure oscillations in the gas may include generating pressure oscillations while changing the gas flow rate.

[0017]

[0017] Flowing gas may involve increasing the gas flow rate, and generating pressure oscillations in the gas may involve generating pressure oscillations during or immediately before increasing the gas flow rate. Generating pressure oscillations in flowing gas may, at least in part, involve generating pressure oscillations in flowing gas during a transition from one operating state to another for the radiation source container. Generating pressure oscillations in flowing gas may, at least in part, involve generating pressure oscillations in flowing gas during a transition from a misoperation to a hit operation for the radiation source container. Generating pressure oscillations in flowing gas may, at least in part, involve generating pressure oscillations in flowing gas during a transition from a hit operation to a misoperation for the radiation source container.

[0018]

[0018] In a more general embodiment, an EUV source is provided. The EUV source includes a radiation source container, a gas conduit, chamber, or manifold connected to the radiation source container for delivering gas from a gas source into the interior of the radiation source container, and an oscillator positioned within a portion of the gas conduit, chamber, or manifold for providing pressure vibrations within the gas in the gas conduit, chamber, or manifold.

[0019]

[0019] The embodiments may include one or more of the following:

[0020]

[0020] The gas source is configured to increase or decrease the gas flow into the radiation source container, and the EUV source further includes a controller connected to the oscillator, the controller may be configured at least in part to vibrate the oscillator during a transition from one operating state to another for the radiation source container. The gas source is configured to increase or decrease the gas flow into the radiation source container, and the EUV source further includes a controller connected to the oscillator, the controller may be configured at least in part to vibrate the oscillator while increasing or decreasing the gas flow into the radiation source container.

[0021]

[0021] In yet another general embodiment, a method for operating an EUV light source is provided. The method includes passing a flow of gas and plasma-generating byproducts into the outlet of the radiation source vessel of the EUV source, and generating one or more pulse trains of gas and / or plasma-generating gas byproducts inside and / or into the outlet, wherein the pulse trains are at least partially directed in the direction of the flow.

[0022]

[0022] In yet another general embodiment, the EUV source includes a radiation source vessel including an outlet, and an oscillator configured to generate pressure oscillations that propagate through an aperture into the outlet. The aperture is configured to generate a pulse train directed at least partially toward or toward the outlet, away from the main volume of the radiation source vessel.

[0023]

[0023] Details of one or more embodiments are described in the attached drawings and the following description. Other features will also become apparent from these descriptions and drawings, and from the claims. [Brief explanation of the drawing]

[0024] [Figure 1]

[0024] This is a schematic cross-sectional view of an embodiment of the EUV light source. [Figure 2]

[0025] This is a schematic cross-sectional view of an EUV light source that works in conjunction with an exposure system. [Figure 3A]

[0026] It is a schematic cross-sectional view of a part of a radiation source container and a collector according to an aspect of the present disclosure. [Figure 3B]

[0026] It is a schematic cross-sectional view of a part of a radiation source container and a collector according to an aspect of the present disclosure. [Figure 4A]

[0027] It is a cross-sectional view (xz plane) of an example of a liner. [Figure 4B]

[0027] It is a cross-sectional view (xz plane) of an example of a liner. [Figure 5]

[0028] It is a schematic cross-sectional view (yz plane) of another example of a liner. [Figure 6]

[0029] It is a schematic cross-sectional view of another example of a liner cut along the xy plane perpendicular to the plane of FIG. 5. [Figure 7]

[0030] It is a schematic cross-sectional view (yz plane) of another example of a liner. [Figure 8]

[0031] It is a schematic cross-sectional view of another example of a liner cut along the xy plane perpendicular to the plane of FIG. 7. [Figure 9]

[0032] It is a schematic cross-sectional view (yz plane) of another example of a liner. [Figure 10]

[0033] It is a schematic cross-sectional view of another example of a liner cut along the xy plane perpendicular to the plane of FIG. 9. [Figure 11]

[0034] It is a close-up cross-sectional view of an example of a liner wall. [Figure 12]

[0035] It is a close-up cross-sectional view of another example of a liner wall. [Figure 13]

[0036] It is a close-up cross-sectional view of another example of a liner wall. [Figure 14]

[0037] It is a close-up cross-sectional view of another example of a liner wall. [Figure 15]

[0038] It is a flowchart of the process of the present disclosure. [Figure 16]

[0039] This is a schematic cross-sectional view of a portion of a radiation source vessel and related or connected structures, in accordance with additional aspects of the present disclosure. [Figure 17]

[0040] This is a schematic cross-sectional view of an embodiment of a conduit, chamber, or manifold equipped with a vibrator. [Figure 18]

[0041] This is a schematic cross-sectional view of an alternative embodiment of the manifold. [Figure 19]

[0042] This is a flowchart of the process for operating the EUV source in relation to the principles discussed with reference to Figures 16 to 18. [Modes for carrying out the invention]

[0025]

[0043] Figure 1 is a simplified schematic cross-sectional view of some components of an embodiment of the LPP EUV light source 110. As indicated by the reference coordinate axes in this figure, Figure 1 is shown in the xz plane. x is positive upwards in the plane of the paper, z is positive to the right in the plane of the paper, and the z axis is aligned with the optical axis A of the collector 120 described below.

[0026]

[0044] As shown in Figure 1, the EUV light source 110 includes a source laser 112. This source laser 112 generates a pulsed light beam 113 (e.g., a pulsed laser beam) and delivers this pulsed light beam 113 from the source laser 112 into the interior 114 of the source container 111 to individually irradiate targets 115 within the irradiation area 116. The light beam 113 can be delivered from the source laser 112 by a beam delivery system 126. The delivery system 126 includes or can work in conjunction with a focusing unit 126a which includes one or more optical elements (not shown) for focusing the pulses of the light beam 113 to a focal point or beam waist near the irradiation area 116.

[0027]

[0045] The EUV light source 110 includes a target delivery system 117 that delivers a target 115 to an irradiation site 116 inside the radiation source container 111. The target 115 moves downward in the plane of the paper (in the negative x-direction) from the target delivery system 117 to the irradiation site 116. At the irradiation site 116, a portion of the target 115 interacts individually with one or more light pulses (of the light beam 113) to generate a plasma 118 that produces EUV light. A portion of the generated EUV light is shown as EUV light 119, but it should be understood that EUV light is emitted in all directions from the plasma 118. The emission, including light such as light 119 from the plasma 118, the position of the target 115, and other data can be monitored by one or more metronome devices 150, and the information collected by one or more metronome devices 150 can be used for the control and operation of the EUV light source 110.

[0028]

[0046] Target 115 is, but is not limited to, an EUV-emitting target material such as tin, lithium, xenon, or a combination thereof, or includes such an EUV-emitting target material. Target 115 can be in the form of a droplet, or a solid particle or solid particles contained within a droplet. For example, elemental tin may be provided as a target in the form of pure tin, tin compounds such as SnBr4, SnBr2, SnH4, tin alloys such as tin-gallium alloys, tin-indium alloys, or tin-indium-gallium alloys, or combinations thereof.

[0029]

[0047] The EUV light source 110 may also include a collector 120. An aperture 125 is formed in the collector 120, and the light beam 113 of the light pulse generated by the radiation source laser 112 can reach the irradiation site 116 through the aperture 125. The collector 120 may be a perinormal incident collector mirror having an optical axis A and a reflecting surface 121. The reflecting surface 121 may be in the form of a long sphere (i.e., an ellipse rotated around its major axis), and the collector 120 has a first focal point or primary focal point 122 in or near the irradiation site 116 and a second focal point at a so-called intermediate focal point 123, with the optical axis A (described above) defined as a line extending between them.

[0030]

[0048] The radiation source container 111 includes an inner surface 156 that at least partially surrounds a volume through which EUV light 124 is transmitted by the collector 120 from the primary focus 122 to the intermediate focus 123 (i.e., within a conical volume around the optical axis A) during use of the EUV light source 110 and the radiation source container 111. The inner surface 156 can be the inner surface of a liner 127 or the wall 127w of the liner 127. The liner 127 can be a part (or more parts) of the radiation source container 111 that surrounds the volume through which EUV light 124 is transmitted. Thus, the inner surface 156 can be considered the inner surface of the radiation source container 111, and more specifically, the inner surface of the liner 127. The EUV light 124 from the collector 120 is output from the EUV light source 110 at the intermediate focus 123 and can be input to a device that utilizes the EUV light 124, such as an exposure apparatus.

[0031]

[0049] To reflect the EUV light 119, the collector 120 can be in the form of a multilayer mirror (MLM). The reflective surface 121 has a stepped multilayer coating including alternating layers of molybdenum and silicon, and optionally also has one or more high-temperature diffusion barrier layers, smoothing layers, capping layers, and / or etch-stopping layers. It is also possible to use a surface shape other than an elongated sphere for the reflective surface 121. For example, the reflective surface 121 may alternatively be in the form of a parabola rotated around its long axis. In this embodiment, the reflective surface 121 can be configured to emit a beam of EUV light 124 having a ring shape or other cross-section at the intermediate focal point 123. In other embodiments, the reflective surface 121 may utilize coatings and layers other than or added to those described above.

[0032]

[0050] The collector 120 can be expensive to manufacture. The efficiency and power of the light generated by the EUV light source 110 depend on the quality of the reflective surface 121 of the collector 120. For these and other reasons, it is desirable to protect the collector 120 from damage to the reflective surface 121 or other performance degradation.

[0033]

[0051] However, in order to collect and redirect the EUV light 119 and deliver the EUV light 124 to the intermediate focus 123, the collector 120 must be positioned in close proximity to the plasma 118 within the radiation source vessel 111. Therefore, the structure within the radiation source vessel 111, including the collector 120, may be exposed to high-energy ions and / or particles and vapors of the target material or the target material. These target material particles and high-energy ions and vapors are essentially debris or by-products resulting from the photo-induced evaporation or ablation process of the target material, or target material that is not irradiated by the laser. These target material particles and high-energy ions and vapors can contaminate the exposed reflective surface 121 of the collector. Furthermore, these target material particles and high-energy ions and vapors may cause physical damage and localized heating of the reflective surface 121 of the collector 120.

[0034]

[0052] Figure 2 shows an embodiment of the EUV light source 210 together with the exposure apparatus 271. The exposure apparatus 271 receives the EUV light 224 generated by the EUV light source 210 and reflects the EUV light 224 with one or more illumination mirrors 272 to illuminate a reflection pattern or reticle 273. The EUV light 224 reflected from the pattern or reticle 273 is further reflected and reduced by one or more reduction mirrors 274 and irradiated onto a substrate or wafer 275 (or onto one or more photosensitive layers on a substrate or wafer 275, not shown) to create a patterned structure inside or on the substrate or wafer 275.

[0035]

[0053] Figure 3A is a schematic cross-sectional view of the radiation source container 311 of the EUV light source 110 in Figure 1, or of an EUV light source in a different radiation source container and EUV light source, and is a yz-plane view showing the y and z directions. The gravity vector G pointing downward in the plane of the paper indicates that the radiation source container 311 may be operating at a certain angle with respect to gravity as illustrated, but is not limited to any specific angle shown in Figure 3A. Various gas flows that may be used in the radiation source container 310 are represented by white arrows.

[0036]

[0054] Referring to Figure 3A, a gas flow, such as a flow of hydrogen (H2) gas at a pressure in the range of approximately 50 to approximately 300 Pascals (Pa), can be used as a buffer gas for debris and / or vapor control within the radiation source vessel 311. Assuming that a vacuum is required inside the radiation source vessel 311 314 to avoid excessive absorption of EUV light by the gas molecules, it would be difficult or impossible to adequately protect the collector 320 from target material debris and vapor emitted from the irradiation site 316 without using a gas flow. Hydrogen (H2) is relatively transparent to EUV radiation with a wavelength of approximately 13.5 nm.

[0037]

[0055] H2 gas is introduced into the radiation source container 311 or into the liner 327 of the radiation source container 311 to slow down and guide high-energy debris (ions, atoms, and clusters) of the target material generated by the irradiation of the target at the irradiation site 316 (not shown in Figure 3A) and the resulting plasma 318. The debris is slowed down by collisions with gas molecules. A forward flow 336 of H2 gas at the central aperture 325 of the collector 320 can be used for this purpose. The forward flow 336 can be guided by a cone tube or nozzle 337, etc., from the central aperture 325 of the collector 320 towards the irradiation site 316 where the plasma 318 is repeatedly generated. This direction is opposite to the debris trajectory from the irradiation site 316 to the collector 320, and therefore the forward flow 336 acts to reduce damage to the collector 320 caused by the deposition, injection, and accumulation of the sputtered target material.

[0038]

[0056] The lateral flow 339 can be directed along the surface of the collector 320 (from an outlet not shown). A so-called showerhead flow is a gas flow through multiple parallel apertures that are generally perpendicular to the surface to be protected, and for example, showerhead flows S1 and S2 can be provided to the area of ​​the radiation source container 311 closest to the collector 120. In additional areas, such as the area near the intermediate focus 323, a protective gas flow having a flow component parallel to or directed parallel to the surface to be protected can be introduced through apertures directed to have a component along or parallel to the surface to be protected. For example, gas flows such as F1, F2, F3, and F4, which can take the form of a curtain flow, can be introduced to protect the inner surface 356 of the radiation source container 311 or liner 327 in the area near the intermediate focus 323.

[0039]

[0057] The backflow 338 is one or more gas flows used to prevent material from leaving the radiation source container 311 in the region of the intermediate focus 323. The backflow 338 flows from the area of ​​the intermediate focus 323 towards the irradiation site 316. This backflow 338 can also be called the “intermediate focus protection” gas flow 338.

[0040]

[0058] A stable induced flow 340, flowing away from the collector 320, can be formed primarily by the forward flow 336, and further together with the lateral flow 339 and showerhead flows S1 and S2 (and others optionally not shown). In Figure 3A, an example of the induced flow 340 is defined by a solid curve. This induced flow 340 helps carry out material containing vapor, ions, particulate matter, and nanoparticles generated from the target 315 during plasma generation from the collector 320. A counterflow 341, moving from the intermediate focus 323 towards the collector 320, can be formed primarily by the reverse flow 338, and further together with flows F1, F2, F3, and F4 (and others optionally not shown). In Figure 3A, an example of the counterflow is defined by a dotted curve. The induced flow 340 and the counterflow 341 merge in a confluence region 342 near the discharge opening 355 in the discharge port 333 of the liner 327. The discharge port 333 can be connected to one or more vacuum pumps (not shown) to remove the combined flow from the radiation source container 311. The induced flow 340 helps to guide the target material byproducts into the discharge opening 355 without substantially contacting the liner 327, the liner wall 327w, and / or one or more inner surfaces 356 of the radiation source container 311.

[0041]

[0059] To facilitate the movement of the induced flow toward the discharge opening 355 and exit from the discharge opening 355, the relative gas flow rates from the showerhead flows S1 and S2 may vary along the inner surface 356 of the liner 327 in the direction of the optical axis A' (along the z-axis) extending from the aperture 325 to the intermediate focal point 323. In Figure 3A, the relative varying flow rates are symbolically represented by the relative variation in the lengths of the white arrows for the showerhead flows S1 and S2. Accordingly, according to one aspect of the present disclosure, a liner 327 is provided for a radiation source container 311 for generating extreme ultraviolet (EUV) light. The liner 327 includes a wall 327w, the inner surface 356 of the wall 327w extending from the collector end 356c of the inner surface 356 toward the intermediate focal end 356if of the inner surface 356. The discharge opening 355 extends through the inner surface 356 and begins at a distance D along the inner surface 356 from the collector end 356c toward the intermediate focal end 356if. Distance D is substantially perpendicular to the collector end 356c. The inner surface 356 also has gas inlets 328 (at the positions where the arrows of the showerhead flows S1 and S2 penetrate the liner wall 327w). (See also Figures 4A and 4B discussed below.) Each gas inlet 328 is located at various positions along the inner surface 356 from or near the collector end 356c to or near distance D. At least some of the gas inlets 328 are configured to supply gas flow at varying flow rates depending on their position along distance D in order to reduce deposits on the inner surface 356. In embodiments such as that shown in Figure 3A, the gas inlet 328 is configured to guide the debris flow in the form of a guided flow 340 that starts at or near the primary focal position 316 and proceeds toward the discharge opening 355. The flow rates of the showerhead flow S1 and showerhead flow S2 are asymmetrical along the direction of the optical axis A'. In some embodiments, the showerhead flow S1 maintains a constant flow rate, while the flow rate of the showerhead flow S2 decreases as it moves from the collector end 356c of the inner surface 356 toward or toward a distance D along the inner surface 356. In some embodiments, the showerhead flow S2 maintains a constant flow rate, while the flow rate of the showerhead flow S1 increases toward the collector end 356c of the inner surface 356.In some embodiments, the flow rate of the showerhead stream S1 decreases linearly as it moves from the collector end 356c of the inner surface 356 toward or toward a distance D along the inner surface 356, and the flow rate of the showerhead stream S2 increases linearly from the collector in the direction extending from the collector end 356c of the inner surface 356.

[0042]

[0060] Figure 3B shows the same schematic cross-section of a portion of the EUV light source 310 shown in Figure 3A, but the flow rates of the showerhead flows S1 and S2 are different from those shown in Figure 3A. In at least one embodiment, as shown in Figure 3B, the variation in flow rate along the inner surface 356 of the liner 327 with respect to the distance D from the collector end 356c does not have to be linear, but can have a nonlinear variation (i.e., can vary nonlinearly). For example, the flow rate can increase exponentially or decrease logarithmically with respect to the distance D (or take other forms). Also, if the flow variation increases on the inner surface 356 of the liner 327 opposite the discharge opening 355 (i.e., showerhead flow S1), it does not necessarily have to increase beyond the distance D from the collector end 356c of the inner surface 356 of the liner 327, but can optionally decrease from a point at or beyond the distance D, as shown in the showerhead flow S1 in Figure 3B. In some embodiments, the flow rates of the showerhead flow S1 and S2 can be any combination of linear and nonlinear distributions. In some examples, the fluctuation of the flow rate of the showerhead flow S1 is nonlinear, and the fluctuation of the flow rate of the showerhead flow S2 is linear. In some examples, the flow rates at the bottom of the showerhead flows S1 and S2 are distributed nonlinearly, and the flow rates at the top of the showerhead flows S1 and S2 are distributed linearly.

[0043]

[0061] Figures 4A and 4B are schematic cross-sectional views of the lower part of liner 427, such as liner 327 in Figures 3A and 3B and liner 127 in Figure 1. The figures in Figures 4A and 4B are in the same xz plane as Figure 1, but are shown in the orientation indicated (positive z is upward in the plane of the figure). Also, Figures 4A and 4B differ from Figure 1 in that, similar to the cross-section of the liner, the area of ​​the inner surface 456 at the bottom of liner 427 is visible. The figures in Figures 4A and 4B are different from each other; Figure 4B is viewed from the negative y direction along the y axis, so a part of the discharge opening 455 is visible, whereas Figure 4A is viewed from the opposite side of the inner surface 456 (the opposite half of the inner surface 456) from the opposite direction, so the part of the discharge opening 455 is not visible.

[0044]

[0062] Referring to Figures 4A and 4B, the liner 427 includes a plurality of gas inlets 428 extending through the liner wall 427w. At least of the gas inlets 428 located within a first elongated area EA1 of the inner surface 456 of the liner 427 provide a flow rate that increases with distance along the distance D from the collector end 456c of the inner surface 456. At least of the gas inlets 428 located within a second elongated area EA2 of the inner surface 456 of the liner 427 provide a flow rate that decreases with distance along the distance D from the collector end 456c. As shown in the figures, the second elongated area EA2 extends from near the collector end 456c to near the nearest edge of the discharge opening 455, and the first elongated area EA1 extends from near the collector end 456c to near the opposite side of the nearest edge of the discharge opening 455. One or more such extension directions can be generally direction D, i.e., one or more directions that are generally coplanar with the optical axis A in Figure 1. In this context, “near” the end 456c is understood to be within the range from as close as possible to the end 456c of the inner surface 456 to 10% of the distance D from the end 456c of the inner surface 456. Similarly, “near” the nearest edge of the discharge aperture is understood to be within the range from as close as possible to the nearest edge of the discharge aperture 455 to 10% of the distance D from the nearest edge of the discharge aperture 455. As shown in Figures 4A and 4B, the volume within the inner surface 456 of the liner 427 has a cross-section that decreases as it approaches the collector end 456c of the inner surface 456 and the intermediate focal end (not shown). The inner surface 456 of the liner 427 may also have a conical shape with a circular cross-section. This can be seen in Figures 4A and 4B, as well as in Figures 5 and 6 (and other figures) which will be discussed below.

[0045]

[0063] The circumferential widths of the elongated areas EA1 and EA2 do not need to be exactly as shown. The circumferential widths of the two elongated areas EA1 and EA2, when measured in an angular range along the circumference of the liner 427, can be, for example, from 20 or 30 degrees to approximately or substantially 180 degrees, and these two areas do not need to have the same or constant circumferential / angular width overall along the distance / direction D (Figures 3A and 3B). As shown in Figures 4A and 4B, the second elongated area EA2 can be on the opposite side of the first elongated area EA1 on the inner surface 456 (in other words, opposite the first elongated area EA1, or positioned 180 degrees from the first elongated area EA1). In at least one embodiment, the flow rate distribution of the first elongated area EA1 is symmetrical with respect to the center line C1, and the flow rate distribution of the second elongated area EA2 is symmetrical with respect to the center line C2.

[0046]

[0064] Figure 5 is a schematic cross-sectional view similar to Figures 4A and 4B, in that it shows the inner surface of half of the liner 527, but this figure is in the same plane as the cross-sections of Figures 3A and 3B, cut at a 90-degree angle to Figures 4A and 4B, with the positive z direction extending upward in the plane of the paper. In the embodiment shown in Figure 5, the flow rates provided by the inlet 528 (represented as the base of the arrows extending from the inner surface 556) (these flow rates are represented by the length of the arrows extending from the inner surface 556 of the liner 527) increase or decrease linearly with respect to the distance from the collector end 556c of the inner surface 556. (For clarity, this figure shows only the flow at or near the left and right edges of the inner surface 556.) Also, in the liner 527 of Figure 5, the primary flow direction generated from the inlet is at a 90-degree angle to the inner surface 556 at each position of each inlet in the plane of the figure, as indicated by the right angle RA in the lower left of the figure.

[0047]

[0065] Figure 6 shows a cross-section of the liner 627, shown as a section cut along line 6-6 of Figure 5, although the cross-sectional configurations shown in Figures 5 and 6 can be implemented independently. For example, a liner configured as shown in Figure 7 and / or Figure 9 (discussed below) may have the same or similar cross-sectional xy planes as the liner 627 in Figure 6. Referring to Figure 6, in the embodiment, the flow rate can be gradually reduced (or increased) as the distance progresses along the circumference of the inner surface of the liner in a plane perpendicular to the optical axis A (Figure 1), for example, from the first elongated area EA1 in Figure 4A to the second elongated area in Figure 4B (or vice versa). In the embodiment of the liner 627 shown in Figure 6, the flow rate provided gradually decreases linearly depending on the position along the circumference of the liner 627, from position P1 opposite the discharge opening (not shown in this figure; see Figure 5) to position P2 circumferentially aligned with the discharge opening (not shown in this figure; see Figure 5). In liner 627, the primary flow direction generated from the inlet in this embodiment is at a 90-degree angle with respect to the inner surface 656 at each position of each inlet in the plane (xy-plane) of the figure. This is shown, for example, by the primary flow direction at the lower center inlet of the cross section in Figure 6 being perpendicular RA1 with respect to the inner surface 656 at that position.

[0048]

[0066] Figure 7 shows another embodiment of the liner 727 in a schematic cross-sectional view similar to that of Figure 5. In the liner 727, at least a portion of the main flow direction generated from the inlet varies from an angle of 90 degrees with respect to the inner surface 756 at each position of each inlet (deviating in various ways from the 90-degree angle). Specifically, in the liner 727, the main flow direction generated by the inlet varies from an angle of 90 degrees with respect to the inner surface 756 at each position of each gas inlet, increasing toward the discharge opening 755. The variation in this embodiment is in the plane of the figure, in other words, in the plane containing the optical axis A (Figure 1), and increases as the distance from the collector end 756c of the inner surface 756 increases. In the illustrated embodiment, the inlet closest to the collector end 756c of the inner surface 756 is perpendicular to the inner surface 756, as shown by the right angle RA2 in the lower left of the figure. As the distance from the collector end 756c increases, the inlet gradually "bends" toward the discharge opening 755. For example, the entrance in the upper left of the diagram is fluctuating (i.e., changing) by an angle θ1 from the right angle RA3.

[0049]

[0067] Figure 8 is a diagram of an embodiment of the liner 827 shown as a cross-section of Figure 7, cut along the line 8-8 of Figure 7, although the cross-sectional configurations shown in Figures 7 and 8 can be implemented independently. For example, a liner configured as shown in Figure 5 (described above) and / or Figure 9 (discussed below) may have the same or similar cross-sections in the xy plane as the liner 827 of Figure 8. In the liner 827 of Figure 8, the primary flow direction provided by the inlet varies to deviate from 90 degrees relative to the inner surface 856, depending on the distance along the circumference of the inner surface 856 of the liner 827. The variation in this embodiment is in the plane of the figure (xy plane), in other words, in the plane perpendicular to the optical axis A (Figure 1). In liner 827, the primary flow direction provided by the inlet varies at each position of each gas inlet from an angle of 90 degrees relative to the inner surface 856 towards the discharge opening as the circumferential distance from position P1 (opposite the circumferential position of the discharge opening) and position P2 (circumferentially aligned with the discharge opening) increases. The discharge opening is not visible in Figure 8; see, for example, Figure 7. Substantial, each primary flow direction "bends" in the plane of the figure (xy plane) (and also in a plane roughly parallel thereto, i.e., perpendicular to the optical axis A in Figure 1) from 90 degrees relative to the inner surface 856 towards the discharge opening. This is shown, for example, at the lower center of the cross section in Figure 8, where the primary flow direction of the inlet at this lower center varies (i.e., changes) by an angle θ2 from a right angle RA4 toward the discharge opening (not shown; see, for example, the discharge opening 755 in Figure 7).

[0050]

[0068] Figure 9 shows another embodiment of the liner 927 in a schematic cross-sectional view similar to that of Figures 5 and 7. In the liner 927, the flow rate generated by the inlet increases in steps depending on the distance from the collector end 956c of the inner surface 956, with each step including two or more gas inlets. As schematically shown in Figure 9, multiple plenums P1 to P8 can be used to provide increasing and decreasing flow rates. Each plenum P i A group consisting of multiple entrances is given, and each plenum P iThis refers to each of the multiple mass flow controllers M1 to M8. i The mass flow controllers M1-M4 and M5-M8 can be supplied with gas flows GF1 and GF2, respectively, from sources not shown. During operation, the mass flow controllers M1-M8 can be signaled or pre-set to generate a desired flow rate that increases (and decreases) with respect to the inner surface 956 from the collector end 956c, as described above with reference to Figures 4A and 4B with respect to the liner 427.

[0051]

[0069] Figure 10 is a diagram of an embodiment of liner 1027 in which there is no gas flow device outside the liner wall of Figure 9, shown as a cross section of Figure 9 cut along line 10-10 of Figure 9. However, the cross-sectional configurations shown in Figures 9 and 10 can be implemented independently. For example, a liner configured as shown in Figure 5 and / or Figure 7 (mentioned above) may have the same or similar cross-sectional xy plane as liner 1027 of Figure 10. In liner 1027 of Figure 10, a stepwise variation in flow rate occurs depending on the circumferential position on the inner surface 1056 of liner 1027. Within a first area A1 (shown in the figure by a circumferential bracket), a certain flow rate (shown in the figure by the relative length of the arrow) is provided, and this area A1 may correspond to the first elongated area EA1 in Figure 4A. Within a second area A2 (shown in the figure by another circumferential bracket), a different flow rate is provided, and this area A2 may correspond to the second elongated area EA2 in Figure 4B. Within the first connection area CA1 and the second connection area CA2, a third flow rate is provided that is less than the flow rate of the first area A1 and greater than the flow rate of the second area A2. In this embodiment, each of the four areas A1, A2, CA1, and CA2 includes seven inlets. Thus, in the embodiment of Figure 10, the flow rate varies in stages in groups of seven inlets, so there are a total of four stages around the circumference of liner 1027. It should be noted that this is in contrast to the embodiments of liners 627 and 827 discussed with reference to Figures 6 and 8, where the flow rate varies from inlet to inlet.

[0052]

[0070] For example, embodiments of the liner wall that can be used as embodiments of the liner 327w in Figures 3A and 3B are shown in the cut-off cross-sections of the leading edge in Figures 11 to 14. Figure 11 shows a partial cross-sectional view of the liner wall 1227w, where the inlet 1128 takes the form of a through-hole that extends through the wall 1127w and becomes progressively smaller (from left to right in the figure). Using through-holes of different diameters is one method for generating flow that varies depending on the location along the liner wall, such as the liner wall 1127w. Figure 12 shows a partial cross-sectional view of the liner wall 1227w, where the plenum structure 1229 forms multiple plenums Pn along the wall 1127w in a direction from left to right in the figure. Supplying gas flows with different pressures or flow rates (supplies are not shown; see, for example, Figure 9) to the continuous plenums Pn is another method for generating flow that varies depending on the location along the liner wall, such as the liner wall 1227w. Figure 13 shows a partial cross-sectional view of a liner wall 1327w, where different flow limits (or flow limiters) are positioned at and / or connected to the inlet 1328 along the left-to-right direction in the figure. In this example, the limiters are in the form of insertions 1330 having through holes 1331 of different diameters. Figure 14 shows a partial cross-sectional view of a liner wall 1427w, where different flow limits (or flow limiters) in the form of insertions 1431 are used together with a plenum structure 1429 that generates multiple plenums Pn along the wall. Combining a continuous plenum Pn with gas flows having different pressures or flows (the supply is not shown; see, for example, Figure 9) and different flow limits or limiters is another method for generating flows that vary with distance (or location) along a liner wall such as a liner wall 1427w. Alternatives not shown in Figures 13 and 14 include flow limiters positioned upstream of inlets 1328 and 1428, and flow limiters positioned downstream of inlets 1328 and 1428 (and other protruding nozzles not shown).

[0053]

[0071] Figure 15 shows the process P100 for operating the EUV light source. As shown in Figure 15, the process includes flowing gas from inlets (328 in Figures 3A and 3B, 428 in Figures 4A and 4B) located at various positions along the inner surface (356 in Figures 3A and 3B, 456 in Figures 4A and 4B) of the radiation source container and / or liner wall (327w in Figures 3A and 3B, 427w in Figures 4A and 4B) (S10), flowing gas from an inlet located within a first elongated area (EA1 in Figure 4A) at a flow rate that increases with distance (distance D in Figures 3A and 3B) from the inner collector end (356c in Figures 3A and 3B, 456c in Figures 4A and 4B) (S20), and flowing gas from an inlet located within a second elongated area (EA2 in Figure 4B) at a flow rate that decreases with distance from the collector end (S30). In some embodiments, operation S10 is optional. In some embodiments, operations S20 and S30 can be performed in parallel or in reverse order. In some embodiments, operations S20 and S30 are performed in a loop until a predetermined threshold is satisfied, such as a tin deposition thickness considering a specific number of pulses. Within process P100, the second elongated area extends from near the collector end to near the nearest edge of the inner discharge opening (355 in Figures 3A and 3B, and 455 in Figures 4A and 4B), and the first elongated area extends from near the collector end to near the opposite side of the nearest edge of the discharge opening (see Figures 4A and 4B above). Embodiments of process P100 may include one or more of the following:

[0054]

[0072] Process P100 may further include, at least in part, flowing gas at an increasing flow rate by using a first set of flow controllers (M1-M4 in Figure 9) connected to an inlet located within a first elongated area. Process P100 may further include, at least in part, flowing gas at a decreasing flow rate by using a second set of flow controllers (M5-M8 in Figure 9) connected to an inlet located within a second elongated area. Process P100 may further include, at least in part, flowing gas at a decreasing flow rate by using a flow limiter / limiter (e.g., insertion part 1330 in Figure 13, 1430 in Figure 14) positioned or connected to the inlet such that the limit increases with distance from the collector end within the first elongated area (e.g., distance D in Figures 3A and 3B). Similarly, process P100 may further include, at least in part, flowing gas at an increasing flow rate by using a flow limiter positioned or connected to the inlet such that the limit decreases with distance from the collector end.

[0055]

[0073] Additional aspects of this disclosure address contamination of the inner surface of the source container of an EUV light source during transient operation. Referring to Figure 1, when an EUV light source such as the EUV light source 110 in Figure 1 is generating EUV light, a continuous target 115 is irradiated by the pulsed light beam 113 of the source laser 112 to generate plasma 118 at the irradiation site 116. This initial operating state of the EUV light source 110 can be called the “hit” operation or “hit” mode. However, there are times during the operation of the EUV light source 110 when the generation of EUV light is undesirable. This is, for example, when the associated exposure apparatus is moving between pattern positions on the wafer or moving from one wafer to the next. In such cases, the timing of the pulses of the pulsed light beam 113 can be adjusted or shifted so that the pulses do not hit the target 115, and therefore the target is not irradiated by the pulses. The target can simply pass through the irradiation site 116 without being irradiated and be received by a target trap (not shown). This second operating state of an EUV light source, in which EUV light is not generated, can be called "miss" operation or "miss" mode.

[0056]

[0074] In EUV light sources such as the EUV light source 110 in Figure 1 and similar radiation sources, transitions from misfires to hits, or from hits to misfires, can cause transitions in the gas flow pattern ("transient states" or "transient flow conditions") within the radiation source container 111. These transitions can have negative effects. For example, a transition from a misfire to a hit may cause plasma 118 to appear relatively suddenly at the irradiation site 116, temporarily pushing the target debris and target vapor toward the inner surface of the radiation source container 111 and / or generating vortices in the gas-plasma mixture within the radiation source container 111. As a result, the target debris and vapor may come into contact with and accumulate on the inner surface of the radiation source container 111.

[0057]

[0075] As shown in Figures 3A and 3B, and as discussed with reference to these figures, gas flows such as showerhead flows S1 and S2 and forward flow 336 are used to protect the internal surfaces of the radiation source containers 111 and 311 from target debris and vapor. Although various gas flows can, in principle, be adjusted to satisfy the changing conditions inside the radiation source container 111, the transition from mismode to hit mode and its effects generally occur much faster than the shortest response time of any gas flow change.

[0058]

[0076] Figure 16 is a schematic cross-sectional view of a portion of the EUV light source vessel 1611, which includes relevant and / or connected structures that are particularly useful during transient flow conditions within the interior 1614 of the light source vessel 1611. As generally described with respect to Figures 3A and 3B, the gas can flow into the interior 1614 of the light source vessel 1611 in various flow forms, including showerhead flows S1 and S2, forward flows 1636, lateral flows 1639, reverse flows 1638, and other flows F1-F4 at the top of the light source vessel 1611. These gas flows, in some cases together with other gas flows (not shown), prevent or reduce the accumulation of target debris and vapor on surfaces inside the light source vessel 1611, such as the inner surface 1656 of the light source vessel 1611 and the surface of the collector 1620, and guide and / or entrain the target debris and vapor and plasma residue, moving them from the light source vessel to the outlet 1633 via the discharge opening 1655. In Figure 16, gas supplies GS1, GS2, and GS3 supply gas to the showerhead flows S1 and S2 and the forward flow 1636, respectively.

[0059]

[0077] As described above, various gas flows flowing into the radiation source container 1611 can be adjusted (e.g., by gas supplies GS1, GS2, and GS3) to satisfy the changing conditions within the radiation source container 1611. However, the effect of such flow changes on the flow pattern within the radiation source container occurs slowly compared to the effect caused by the operational transition of the EUV radiation source from mis-operation to hit operation or from hit operation to mis-operation. However, as seen in Figure 16, one or more flows, such as showerhead flows S1 and S2 and forward flow 1636, can be supplied into the radiation source container 1611 via conduits, chambers, or manifolds M1, M2, and / or M3 in which oscillators O1, O2, and / or O3 are positioned or connected. Oscillators O1, O2, and O3 can have a very rapid effect on the flow pattern within the radiation source container 1611.

[0060]

[0078] By vibrating oscillators O1, O2, or O3, pressure oscillations are induced within the corresponding conduits, chambers, or manifolds M1, M2, or M3. These pressure oscillations can generate changes such as an increase in the kinetic energy or momentum of the gas flow generated at or near the outlet of the conduits, chambers, or manifolds M1, M2, or M3 and injected into the interior 1614 of the radiation source container 1611, without changing the average flow rate from the conduits, chambers, or manifolds (represented by multiple parallel arrows in Figure 16). This will be further discussed below with reference to Figure 17.

[0061]

[0079] The transducers O1, O2, and O3 can be similar to speaker cones for subwoofers or other speaker cones. Such transducers are lightweight, powerful, and responsive enough to reproduce music and other sounds with high fidelity, and can therefore start vibrating very quickly and generate pressure fluctuations in the surrounding gas. Pressure waves (or sound waves) propagate through the gas at the speed of sound. Thus, by using one or more transducers O1, O2, and O3 in this way, the momentum and energy of the gas generated in the radiation source container 1611 from various flows (in this embodiment from showerhead flows S1 and S2 and forward flow 1636) can be changed very quickly, that is, not at a slow speed where the effect of increased gas flow can be felt, but at almost the speed of sound.

[0062]

[0080] Furthermore, as shown in Figure 16, the controller CTR can communicate with oscillators O1, O2, and O3, for example, via associated drive signal sources DR1, DR2, and DR3. Using oscillator chambers OC1, OC2, and OC3 together with oscillators O1, O2, and O3, a space and volume can be provided in which the oscillators can move sufficiently freely and interact with a sufficient volume of gas to generate the desired pressure oscillation. The controller CTR can be configured, at least in part, to drive one or more oscillators O1, O2, and O3 during a transition from one operating state to another of the radiation source vessel. The controller CTR can be configured, at least in part, to drive oscillators O1, O2, and O3 while increasing or decreasing the flow of one or more gases into the interior 1614 of the radiation source vessel 1611. The controller CTR can also communicate with gas supplies GS1, GS2, and GS3, as shown in Figure 16, to detect or control the increase or decrease in gas flow. It should be noted that controllers (CTRs) can take many forms, such as not being a centralized controller but rather a distributed control system with mutual communication capabilities, and can be implemented using hardware, software, or a combination thereof.

[0063]

[0081] In addition to or alternative to the features described above, one or more outlets or apertures (corresponding to the positions where the dashed arrows cross the interior of the outlet 1633) located inside or near the discharge opening 1655 and / or discharge port 1633 can be connected directly or via a conduit, chamber, or manifold M5 as shown in the figure to the transducer chamber OC4. The vibration of the membrane or other actuators within this transducer chamber can be generated by a drive signal source DR7, which can be controlled by the controller CTR.

[0064]

[0082] Vibrations of the membrane or other actuators can generate pulse trains PT of gas within or into the source vessel 1611 (within or into the outlet 1633 of the source vessel), as indicated by dashed arrows. In Figure 16, pulse trains PT are indicated by dashed arrows, representing the pulsed nature of the flow within the pulse trains PT. One or more pulse trains PT are directed at least partially toward the interior of the outlet 1633 (in that direction) away from the main volume of the source vessel 1611. In other words, pulse trains PT are directed at least partially toward the flow of gas and plasma generation byproducts passing through the interior of the outlet 1633. Due to the effect of pressure vibrations on the gas present in the oscillator chamber OC4 and manifold M5 (if present), pulse trains PT can be generated without net flow into the source vessel 1611 or its outlet 1633. Optionally, if desired, a small gas flow (not shown) can be provided into the transducer chamber OC4 or into the conduit, chamber, or manifold M5 to keep their inner surfaces clean.

[0065]

[0083] The pulse train PT can be switched on and / or varied almost instantaneously in response to changes in the drive signal from the drive signal source DR7. By switching on or increasing the intensity of the pulse train PT, gas and encompassed plasma generation byproducts can be moved into the outlet 1633 and, if necessary, help to draw gas and encompassed byproducts into the exhaust opening 1655. This resulting increase in draw-in into the exhaust opening 1655 can be used, for example, during, / or immediately before, and / or immediately after the transition of the associated EUV light source from misoperation to hit operation and / or vice versa. In particular, the increase in draw-in into the exhaust opening 1655 can be used to prevent or reduce target vapor and target debris from passing through the exhaust opening 1655 and reaching the space above the exhaust opening 1655.

[0066]

[0084] Figure 17 is a schematic cross-sectional view of a conduit, chamber, or manifold forming a chamber or housing EN in which an embodiment of the transducer O is mounted. The housing EN includes an aperture AP through which gas can flow out of the housing. A gas supply GF into the housing EN can provide a steady flow into the housing and out of the housing via the aperture AP. (It should be noted that the gas supply GF is optional in the transducer chamber OC4 and / or conduit, chamber, or manifold M5 in Figure 16.) With or without flow from the gas supply GF, when the transducer O is driven by an actuator, the resulting pressure oscillations within the housing EN can cause gas pulses to be emitted from the aperture AP.

[0067]

[0085] The actuator shown in this embodiment is a voice coil having a coil CL and a magnet assembly MA including a permanent magnet PM mounted on a magnetic flux guide FG. The magnet assembly MA provides a magnetic field having lines of force (not shown) perpendicular to the direction of the current (not shown) in the coil CL, and a force that varies in accordance with the current in the coil CL is applied to the oscillator O, causing the position of the oscillator O to shift.

[0068]

[0086] When a fluctuating current from the drive signal source DR is supplied to the coil CL, pressure oscillations occur within the housing, and the resulting oscillating jet is pushed out through the aperture AP (and pulled in accordingly, if a net flow exists). The fluctuations can take the form of a square wave or a combination of waveforms approximating a square wave. The residence time at the sharp transitions between the maximum and minimum characteristics of the square wave can be effective in increasing the energy and momentum of the generated gas flow, but other waveforms can also be used. Although not bound by theory, the drag on the intermittent jet flowing out from the side of the aperture AP and from the gas immediately outside the aperture AP slows down the radially outer portion of the intermittent jet, but not the central portion (or the slowing down is delayed in the central portion), which is thought to cause the jet to bend into the form of a vortex ring by poloidal flow (flow along the circumference of the cross-section of the small circle of a toroidal, i.e., "donut" shaped ring). When the flow through aperture AP is repeatedly slowed, stopped, and / or reversed due to the vibration of oscillator O, vortex rings can form, detach from aperture AP, and propagate away from the aperture in the propagation direction PD. Continuous pressure vibrations can generate continuous vortex rings, such as vortex rings VR-1 to VR-4, shown by circular arrows in Figure 17. Such vortex rings, in all or often cases, transfer large momentum and energy over a large distance from the aperture compared to the constant flow rate released from the aperture. Therefore, when the oscillator is vibrated at a frequency typically in the range of 40 Hz to 40,000 Hz, the energy and momentum of the flow from or originating at aperture AP can increase almost instantaneously. This is much faster than an increase in the flow rate of the gas supply GF can produce an effect. In the case of the pulse train PT in Figure 16, even when there is no net flow, vortex rings are generated from the gas in adjacent aperture AP and can often transfer momentum over a larger distance than the effect of a normal gas flow from the same aperture.

[0069]

[0087] Of course, oscillators other than membranes and actuators other than voice coils can be used. Instead of membranes, mechanically or hydraulically actuated pistons can be used to generate high-frequency vibrations of gas pressure. In addition, additional forms of electromechanical actuators, such as piezoelectric, electroactive polymer, and electrostatic actuators, can also be used.

[0070]

[0088] Figure 18 is a schematic cross-sectional view of an alternative embodiment of a manifold M4 having multiple apertures APS. The manifold is supplied from a gas supply GF that generates a gas flow through the apertures APS, indicated by the parallel arrows on the left side of the figure. Multiple vibrating membranes in the form of multiple voice coils VC1, VC2, VC3, VC4, and VC5 provide pressure oscillations within the manifold M4. The voice coils VC1-VC5 can be driven individually, in parallel, or in a combination of individual and parallel drive by one or more fluctuating current sources DR4, DR5, and DR6. A buffer BF is included in the manifold M4 and can help induce and / or confine pressure waves resulting from pressure fluctuations induced by the oscillations of the voice coils VC1-VC5.

[0071]

[0089] Figure 19 is a flowchart of several embodiments of process P1901 for operating an EUV source in relation to the principles discussed with reference to Figures 16 to 18. As shown in Figure 19, process P1901 includes flowing gas into the source vessel of the EUV light source (S1902) and generating pressure oscillations in the flowing gas having a frequency in the range of 40 Hz to 40 kHz. At frequencies lower than 40 Hz, the additional momentum generated for the gas may be less than desired, and at frequencies higher than 40 kHz, the effect of pulsing one or more flows may be reduced, resulting in a continuous flow effect and smaller additional momentum. The pressure oscillations may also be in the range of, for example, 100 Hz to 20 kHz or 100 Hz to 10 kHz. Generating pressure oscillations in one or more gas flows into the source vessel can generate vortices or other energy-containing flow patterns from the aperture opening into the source vessel. Energy-containing flow patterns can be generated almost instantaneously by pressure waves traveling at the speed of sound from a vibrating membrane or the like to the aperture opening into the radiation source container. This almost instantaneous additional energy flow pattern can be used during or near transitions in the operating state of the associated EUV light source. This is, for example, during, immediately before, and / or immediately after, an increase in gas flow rate into the radiation source container, during, immediately before, and / or immediately after, a transition from misoperation to hit operation and / or the reverse transition of the EUV light source. Using pressure oscillations in such situations can help to more quickly adjust or adapt flow conditions within the radiation source container to generate or maintain a desired flow pattern, while also preventing or reducing contamination of the surfaces inside the radiation source container.

[0072]

[0090] Embodiments of the present invention can be further described in the following numbered clauses. 1. Liner for a radiation source container for generating extreme ultraviolet (EUV) light, A wall having an inner surface, the inner surface extending from the collector end of the inner surface toward the intermediate focal end of the inner surface, and the inner surface having an exhaust opening extending through the inner surface, the exhaust opening starting at a distance along the inner surface toward the intermediate focal end, Each gas inlet is positioned at various locations from near the collector end to a distance along the inner surface, A liner comprising, wherein at least some of the gas inlets are configured to supply a gas flow rate that varies depending on each position along the distance. 2. The liner as described in Clause 1, wherein the gas inlet is configured to guide a debris flow that begins near the primary focal point and proceeds toward the discharge opening. 3. The liner according to Clause 1, wherein a gas inlet located in a first elongated area on the inner surface of the liner provides a flow rate that increases along the direction extending from the collector end, and a gas inlet located in a second elongated area on the inner surface of the liner provides a flow rate that decreases along the direction extending from the collector end. 4. The liner as described in Clause 3, wherein the second elongated area extends from near the collector end to near the nearest edge of the discharge opening, and the first elongated area extends from near the collector end to near the opposite side of the nearest edge of the discharge opening. 5. The liner according to Clause 3, wherein the volume within the inner surface of the liner has a cross-section that decreases as it approaches the intermediate focal point from the collector end, and a second elongated area is located opposite the first elongated area. 6. The liner according to Clause 3, wherein the inner surface of the liner has a conical shape with a circular cross-section, the cross-section becoming smaller as it approaches the intermediate focal point from the collector end, and a second elongated area is located opposite the first elongated area. 7. The liner according to Clause 3, wherein the gas inlets are configured to supply a gas flow rate that increases in stages along a distance within a first elongated area, with each stage comprising two or more gas inlets. 8. The liner according to Clause 3, wherein the gas inlet is configured to supply a gas flow rate that increases non-linearly along the direction extending from the collector end along a distance within a first elongated area. 9. The liner described in Clause 3, wherein at least some gas inlets have flow limits that vary depending on their respective locations. 10. The liner as described in Clause 9, wherein at least several gas inlets include holes of different diameters that penetrate the wall of the liner. 11. The liner according to Clause 3, wherein at least some gas inlets are supplied in two or more groups by two or more flow controllers, and the two or more flow controllers are configured to supply flow at each flow rate according to each position in each group. 12. The liner according to Clause 1, further comprising a plurality of gas supply plenums, each of which at least a number of gas inlets is connected to one of the plurality of gas supply plenums. 13. Each of the multiple gas supply plenums is supplied by each flow controller, as described in Clause 12. 14. Each gas inlet guides the flow in each major flow direction at a 90-degree angle to the inner surface at each position of each gas inlet, as described in Clause 1. 15. Each gas inlet guides the flow in each major flow direction at a different angle to the inner surface at each position of each gas inlet, as described in Clause 1. 16. A method for operating an extreme ultraviolet (EUV) light source, Flowing gas into the radiation source container of the EUV light source, To generate pressure oscillations with frequencies in the range of 40 Hz to 40 kHz within a flowing gas, A method that includes this. 17. The method according to Clause 16, wherein generating pressure oscillations in a flowing gas includes generating oscillations in a membrane that is in direct or indirect contact with the flowing gas. 18. The method according to clause 17, wherein the film is connected to a coil positioned in a magnetic field and connected to a supply of a fluctuating current. 19. The method of Article 16, which includes flowing gas in a forward flow. 20. The method according to Clause 16, wherein the flow of gas includes flowing gas from inlets located at various positions along the inner surface of the radiation source container, the inner surface extending from the inner surface collector end toward the inner surface intermediate focal end. 21. The method according to Clause 16, wherein flowing a gas includes changing the flow rate, and generating pressure oscillations in a gas includes generating pressure oscillations while changing the flow rate of the gas. 22. The method according to Clause 16, wherein flowing the gas includes increasing the flow rate of the gas, and generating pressure oscillations in the gas includes generating pressure oscillations during or immediately before increasing the flow rate of the gas. 23. The method according to Clause 16, wherein generating pressure oscillations in a flowing gas includes, at least in part, generating pressure oscillations in a flowing gas during a transition from one operating state to another for a radiation source vessel. 24. The method of Clause 16, which includes generating pressure oscillations in a flowing gas, at least in part, during a transition from misoperation to hit operation of a radiation source vessel. 25. The method of Clause 16, which includes generating pressure oscillations in a flowing gas, at least in part, during a transition from a hit operation to a miss operation of a radiation source vessel. 26. Radiation source container and, A gas conduit, chamber, or manifold connected to the radiation source container for delivering gas from the gas source into the interior of the radiation source container, A vibrator positioned within a portion of a gas conduit, chamber, or manifold to provide pressure vibrations within the gas in the gas conduit, chamber, or manifold, An EUV source equipped with [unclear / unclear]. 27. The EUV source according to Clause 26, wherein the gas source is configured to increase or decrease the gas flow into the interior of the radiation source vessel, and the EUV source further comprises a controller connected to an oscillator, the controller being configured at least in part to vibrate the oscillator during a transition from one operating state to another of the radiation source vessel. 28. The EUV source according to Clause 26, wherein the gas source is configured to increase or decrease the gas flow into the interior of the radiation source vessel, and the EUV source further comprises a controller connected to an oscillator, the controller being configured at least in part to vibrate the oscillator while increasing or decreasing the gas flow into the interior of the radiation source vessel. 29. A method for operating an EUV light source, The process involves passing a flow of gas and plasma generation byproducts through the outlet of the EUV source's radiation source container, Generating one or more pulse trains of gas and / or plasma generation gas byproducts inside and / or into the outlet, wherein the pulse trains are at least partially directed in the direction of flow, A method that includes this. 30. A radiation source container including an outlet, A vibrator configured to generate pressure vibrations that propagate through the aperture into the outlet, An EUV source comprising an aperture configured to generate a pulse train directed at least partially toward or toward the outlet, away from the main volume of the radiation source vessel.

[0073]

[0091] The above-described embodiments and other embodiments are within the scope of the following claims.

Claims

1. Liner for a radiation source container for generating extreme ultraviolet (EUV) light, A wall having an inner surface, wherein the inner surface extends from the collector end toward the intermediate focal end of the inner surface, and the inner surface has a discharge opening extending through the inner surface, the discharge opening starting at a distance along the inner surface from the collector end toward the intermediate focal end, Each gas inlet is positioned at a distance from near the collector end to near the distance along the inner surface, A liner comprising, wherein at least some of the gas inlets are configured to supply a gas flow rate that varies depending on each position along the distance.

2. The liner according to claim 1, wherein the gas inlet is configured to guide a debris flow that starts near the primary focal point and proceeds toward the discharge opening.

3. The liner according to claim 1, wherein a gas inlet located in a first elongated area on the inner surface of the liner provides a flow rate that increases along the direction extending from the collector end, and a gas inlet located in a second elongated area on the inner surface of the liner provides a flow rate that decreases along the direction extending from the collector end.

4. The liner according to claim 3, wherein the second elongated area extends from near the collector end to near the nearest edge of the discharge opening, and the first elongated area extends from near the collector end to near the opposite side of the nearest edge of the discharge opening.

5. The liner according to claim 3, wherein the volume within the inner surface of the liner has a cross-section that decreases as it approaches the intermediate focal point from the collector end, and the second elongated area is positioned on the opposite side of the first elongated area.

6. The liner according to claim 3, wherein the inner surface of the liner has a conical shape with a circular cross-section, the cross-section becomes smaller as it approaches the intermediate focal point from the collector end, and the second elongated area is positioned on the opposite side of the first elongated area.

7. The liner according to claim 3, wherein the gas inlet is configured to supply a gas flow rate that increases in stages along the distance within the first elongated area, and each stage includes two or more gas inlets.

8. The liner according to claim 3, wherein the gas inlet is configured to supply a gas flow rate that increases nonlinearly along the direction extending from the collector end along the distance within the first elongated area.

9. The liner according to claim 3, wherein at least some of the gas inlets have flow limits that vary according to their respective positions.

10. The liner according to claim 9, wherein at least some of the gas inlets include holes of different diameters that penetrate the wall of the liner.

11. The liner according to claim 3, wherein at least some of the gas inlets are supplied in two or more groups by two or more flow controllers, and the two or more flow controllers are configured to supply flow at a flow rate according to each of the positions in each of the groups.

12. The liner according to claim 1, further comprising a plurality of gas supply plenums, wherein each of the at least a plurality of gas inlets is connected to one of the plurality of gas supply plenums.

13. The liner according to claim 12, wherein each of the plurality of gas supply plenums is supplied by each flow controller.

14. The liner according to claim 1, wherein each of the gas inlets guides the flow in each major flow direction at an angle of 90 degrees with respect to the inner surface at each of the positions of each gas inlet.

15. The liner according to claim 1, wherein each of the gas inlets guides the flow in each major flow direction at different angles with respect to the inner surface at each of the positions of each gas inlet.

16. A method for operating an extreme ultraviolet (EUV) light source, The process involves flowing gas into the radiation source container of the aforementioned EUV light source, In the flowing gas, a pressure oscillation having a frequency within the range of 40 Hz to 40 kHz is generated. A method that includes this.

17. The method according to claim 16, wherein generating the pressure vibration in the flowing gas includes generating vibration in a membrane that is in direct or indirect contact with the flowing gas.

18. The method according to claim 17, wherein the film is connected to a coil that is connected to a supply of a fluctuating current and positioned in a magnetic field.

19. The method according to claim 16, wherein the flow of the gas includes flowing a forward flow of gas.

20. The method according to claim 16, wherein the flow of the gas includes flowing the gas from inlets located at various positions along the inner surface of the radiation source container, the inner surface extending from the collector end of the inner surface toward the intermediate focal end of the inner surface.

21. The method according to claim 16, wherein flowing the gas includes changing the flow rate, and generating pressure oscillations in the gas includes generating pressure oscillations while changing the flow rate of the gas.

22. The method according to claim 16, wherein flowing the gas includes increasing the flow rate of the gas, and generating the pressure oscillations in the gas includes generating the pressure oscillations during or immediately before increasing the flow rate of the gas.

23. The method according to claim 16, wherein generating the pressure oscillations in the flowing gas includes, at least in part, generating the pressure oscillations in the flowing gas during a transition from one operating state to another for the radiation source container.

24. The method according to claim 16, wherein generating the pressure oscillations in the flowing gas includes, at least in part, generating the pressure oscillations in the flowing gas during a transition from misoperation to hit operation of the radiation source container.

25. The method according to claim 16, wherein generating the pressure oscillations in the flowing gas includes, at least in part, generating the pressure oscillations in the flowing gas during a transition from a hit operation to a miss operation of the radiation source container.

26. The radiation source container and A gas conduit, chamber, or manifold connected to the radiation source container for supplying gas from the gas source into the interior of the radiation source container, A vibrator positioned within a portion of the gas conduit, chamber, or manifold to provide pressure vibrations within the gas in the gas conduit, chamber, or manifold, An EUV source equipped with [specific features / features].

27. The EUV source according to claim 26, wherein the gas source is configured to increase or decrease the gas flow into the interior of the radiation source container, and the EUV source further comprises a controller connected to the oscillator, the controller being configured at least partially to vibrate the oscillator during a transition from one operating state to another of the radiation source container.

28. The EUV source according to claim 26, wherein the gas source is configured to increase or decrease the gas flow into the interior of the radiation source container, and the EUV source further comprises a controller connected to the oscillator, the controller being configured at least partially to vibrate the oscillator while increasing or decreasing the gas flow into the interior of the radiation source container.

29. A method for operating an EUV light source, The flow of gas and plasma generation byproducts is passed through the interior of the outlet of the radiation source container of the EUV source, To generate one or more pulse trains of gas and / or plasma generation gas byproducts inside and / or into the outlet, wherein the pulse trains are at least partially directed in the direction of the flow, A method that includes this.

30. A radiation source container including an outlet, A vibrator configured to generate pressure vibrations that propagate through the aperture into the outlet, An EUV source comprising, wherein the aperture is configured to generate a pulse train directed at least partially toward or toward the outlet away from the main volume of the radiation source container.

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