Airflow apparatus and method for EUV light sources

Abstract

A liner for a source container for extreme ultraviolet (EUV) light generation includes a wall having an inner surface extending toward an intermediate focus end of the inner surface away from a collector end of the inner surface. The inner surface has an exhaust opening extending therethrough at a distance D along the inner surface from the collector end toward the mid-focus end, and respective airflow inlets are provided at respective locations from near the collector end to near the distance D along the inner surface, wherein at least some of the gas flow inlets are configured to supply a gas flow rate that varies therewith along a respective position of the distance D to reduce deposition on the inner surface. A process or method of operating an EUV light source is also disclosed.

Description

Cross-references to related applications

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

[0002] This disclosure relates to apparatus and methods for controlling the flow of products generated within a source container used to generate extreme ultraviolet (“EUV”) radiation by irradiation of a target, and more particularly to apparatus and methods for providing a gasflow within the container to assist in guiding or controlling the flow of such products. Background Technology

[0003] Extreme ultraviolet (EUV) radiation, such as electromagnetic radiation with wavelengths of about 50 nm or shorter (sometimes referred to as soft X-rays), including radiation with wavelengths of about 13.5 nm, can be used for photolithography processes in semiconductor manufacturing or for inspection processes in quality control. Methods for generating EUV radiation involve converting a target material into a plasma state. The target material includes at least one element, such as xenon, lithium, or tin, which has one or more emission lines in the EUV portion of the electromagnetic spectrum. The target material can be solid, liquid, or gas. In a method commonly referred to as laser-generated plasma (“LPP”), the desired plasma can be generated by irradiating a target material containing one or more EUV line-emitting elements with one or more light pulses using a “source” laser (typically a CO2 laser that emits infrared light with wavelengths of about 10,600 nanometers (nm)). The plasma is typically generated in a sealed “source container,” which is usually a vacuum chamber.

[0004] Generating plasma from target material within a source container can produce vapors, ions, and microparticles and other debris that can deposit and contaminate surfaces (including optical surfaces) inside the source container. Therefore, it is necessary to remove (multiple) residual target material from the source container to reduce or eliminate surface contamination within the source container. Summary of the Invention

[0005] In some general aspects, a liner is provided for a source container for generating extreme ultraviolet (EUV) light, the liner comprising: a wall having an inner surface extending toward a collector end of the inner surface away from a central focal end of the inner surface, the inner surface having an exhaust opening extending through the inner surface toward the central focal end from a distance along the inner surface from the collector end; and corresponding airflow inlets disposed at corresponding positions from near the collector end to near the distance along the inner surface; wherein at least some of the airflow inlets are configured to supply a gas flow rate that varies with the corresponding position of the at least some of the airflow inlets along the distance.

[0006] The implementation may include one or more of the following.

[0007] The airflow inlets can be configured to direct debris flow originating near the focal point toward the exhaust opening. An airflow inlet located within a first elongated region on the inner surface of the liner can provide an increasing flow velocity in the direction extending from the collector end, and an airflow inlet located within a second elongated region on the inner surface of the liner can provide a decreasing flow velocity in the direction extending from the collector end. The second elongated region can extend from near the collector end to near the nearest edge of the exhaust opening, and the first elongated region can extend from near the collector end to near a location opposite the nearest edge of the exhaust opening.

[0008] The volume within the inner surface of the liner may have a cross-section that decreases from the collector end toward the intermediate focal end, and the second elongated region may be positioned opposite the first elongated region. The inner surface of the liner may be conical with a circular cross-section that decreases from the collector end toward the intermediate focal end, and the second elongated region may be positioned opposite the first elongated region.

[0009] The airflow inlets can be configured to supply a gas flow rate along a distance within a first elongated region, the gas flow rate increasing in steps, each step comprising two or more airflow inlets. The airflow inlets can be configured to supply a gas flow rate along a distance within the first elongated region, the gas flow rate increasing non-linearly in a direction extending from the collector end. At least some of the airflow inlets can have corresponding flow limits that vary with their respective locations. At least some of the airflow inlets can be in the form of orifices through the wall of the liner, the orifices varying in diameter. At least some of the airflow inlets can be in the form of orifices through the wall of the liner, with flow restrictors connected to the orifices having varying limits. At least some of the airflow inlets can be supplied by corresponding two or more flow controllers in two or more corresponding groups, the two or more flow controllers being configured to supply flow at corresponding rates according to the corresponding locations of the corresponding groups.

[0010] The liner may also include multiple gas supply chambers (plenums), and each gas supply inlet may be connected to one of the multiple gas supply chambers. Each of the multiple gas supply chambers may be supplied via a respective flow controller. The gas supply inlet may guide the flow in a corresponding primary flow direction, which forms a 90° angle with respect to the inner surface at the corresponding location of the corresponding gas supply inlet. The gas supply inlet may guide the flow in a corresponding primary flow direction having an angle that varies relative to the inner surface at the corresponding location of the corresponding gas supply inlet. The gas supply inlet may guide the flow in a corresponding flow direction, which typically varies at the corresponding location of the gas supply inlet from a 90° angle with the inner surface as the distance from the collector end increases.

[0011] In another general aspect, a method of operating an extreme ultraviolet (EUV) light source is provided, the method comprising: flowing gas from an inlet disposed at a corresponding location on an inner surface of a source container, the inner surface extending from a collector end toward a central focal end of the inner surface; flowing gas at a flow rate increasing with distance from the collector end from an inlet located in a first elongated region on the inner surface; and flowing gas at a flow rate decreasing with distance from the collector end from an inlet located in a second elongated region on the inner surface; wherein the second elongated region extends from near the collector end to near the nearest edge of an exhaust opening in the inner surface, and wherein the first elongated region extends from near the collector end to a location opposite or near the nearest edge of the exhaust opening.

[0012] The implementation may include one or more of the following.

[0013] Flowing gas at an increased flow rate may include using a first plurality of flow controllers connected to an inlet located within a first elongated region. Flowing gas at a decreased flow rate may include using a second plurality of flow controllers connected to an inlet located within a second elongated region. Flowing gas at a decreased flow rate may include using a flow restrictor at or connected to the inlet, with the restriction increasing with distance from the inlet to the collector end within the first elongated region. Flowing gas at an increased flow rate may include using a flow restrictor at or connected to the inlet, with the restriction decreasing with distance from the inlet to the collector end.

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

[0015] The implementation may include one or more of the following.

[0016] Generating pressure oscillations within a flowing gas can 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 connected to a supply of varying current and positioned in a magnetic field. Flowing the gas can include: allowing a forward flow of gas. Flowing the gas can also include: allowing gas to flow from an inlet located at a corresponding position on the inner surface of a source container, the inner surface extending from a collector end toward a central focal end of the inner surface. Flowing the gas can also include: changing the flow rate of the gas, and generating pressure oscillations within the gas can include: generating pressure changes simultaneously with changing the flow rate of the gas.

[0017] Making the gas flow can include increasing the flow rate of the gas, and generating pressure oscillations within the gas can include generating pressure oscillations during or just before increasing the flow rate of the gas. Generating pressure oscillations within the flowing gas can include generating pressure oscillations within the flowing gas at least partially during a transition from one operating state of the source container to another operating state of the source container. Generating pressure oscillations within the flowing gas can include generating pressure oscillations within the flowing gas at least partially during a transition from a miss operation of the source container to a hit operation of the source container. Generating pressure oscillations within the flowing gas includes generating pressure oscillations within the flowing gas at least partially during a transition from a hit operation of the source container to a miss operation of the source container.

[0018] In a more general aspect, an EUV source is provided, comprising: a source container; a gas conduit, cavity, or manifold connected to the source container for delivering gas from a gas source into the interior of the source container; and an oscillator positioned within a portion of the gas conduit, cavity, or manifold for providing pressure oscillation within the gas in the gas conduit, cavity, or manifold.

[0019] The implementation may include one or more of the following.

[0020] The gas source can be configured to increase and decrease the gas flow into the interior of the source container, and the EUV source may further include a controller connected to an oscillator, wherein the controller is configured to cause the oscillator to oscillate at least partially during a transition from one operating state of the source container to another operating state of the source container. The gas source can be configured to increase and decrease the gas flow into the interior of the source container, and the EUV source may include a controller connected to an oscillator, wherein the controller is configured to cause the oscillator to oscillate at least partially during an increase or decrease in the gas flow into the interior of the source container.

[0021] In yet another general aspect, a method of operating an EUV source is provided, the method comprising: passing a flow of gas and plasma-generated byproducts through the interior of an exhaust port of a source container of the EUV source; and generating one or more pulse sequences of gas and / or plasma-generated gas byproducts within and / or inside the exhaust port, the pulse sequences being oriented at least partially in the direction of the flow.

[0022] In yet another general aspect, an EUV source includes: a source container including an exhaust port; and an oscillator configured to generate pressure oscillations propagating through an aperture into the exhaust port; wherein the aperture is configured to generate a pulse sequence that is oriented at least partially in a direction entering or along the exhaust port away from the main volume of the source container.

[0023] Details of one or more embodiments are set forth in the accompanying drawings and the following description. Other features will be apparent from the specification, the drawings, and the claims. Attached Figure Description

[0024] Figure 1 This is a cross-sectional schematic diagram of the realization of the EUV light source.

[0025] Figure 2 This is a cross-sectional schematic diagram of the collaboration between the EUV light source and the exposure device.

[0026] Figure 3A and Figure 3BThis is a cross-sectional schematic diagram of a portion of the source container and collector according to aspects of this disclosure.

[0027] Figure 4A and Figure 4B This is a cross-sectional view of the lining implementation (in the xz plane).

[0028] Figure 5 This is a schematic cross-sectional view of another implementation of the liner (in the yz plane).

[0029] Figure 6 It is perpendicular to Figure 5 A schematic diagram of another implementation of the lining, taken from the xy plane of the plane.

[0030] Figure 7 This is a schematic cross-sectional view of another implementation of the liner (in the yz plane).

[0031] Figure 8 It is perpendicular to Figure 7 A schematic diagram of another implementation of the lining, taken from the xy plane of the plane.

[0032] Figure 9 This is a cross-sectional schematic diagram (in the yz plane) of another embodiment of the liner.

[0033] Figure 10 It is perpendicular to Figure 9 A schematic diagram of another implementation of the lining, taken from the xy plane of the plane.

[0034] Figure 11 This is a close-up cross-sectional view of the inner lining wall.

[0035] Figure 12 This is a close-up cross-sectional view of another realization of the inner lining wall.

[0036] Figure 13 This is a close-up cross-sectional view of another realization of the inner lining wall.

[0037] Figure 14 This is a close-up cross-sectional view of another realization of the inner lining wall.

[0038] Figure 15 This is a flowchart of the process disclosed herein.

[0039] Figure 16 It is a cross-sectional schematic diagram of a portion of the source container and its associated or connecting structures according to other aspects of this disclosure.

[0040] Figure 17 This is a cross-sectional schematic diagram of an embodiment of a conduit, lumen, or manifold with an oscillator.

[0041] Figure 18 This is a cross-sectional schematic diagram of an alternative implementation of the manifold.

[0042] Figure 19 For operation and about Figures 16 to 18 The flowchart of the EUV source process related to the discussed principles is shown. Detailed Implementation

[0043] Figure 1 This is a simplified cross-sectional schematic diagram of some components used in the implementation of the LPP EUV light source 110. As shown by the reference coordinate axes in the figure, Figure 1 Shown in the xz plane, where x is positive in the upward direction of the page plane and z is positive in the right direction of the page plane, with the z axis aligned with the optical axis A of the collector 120, which will be described below.

[0044] like Figure 1 As shown, the EUV source 110 includes a source laser 112 for generating a pulsed beam 113 (e.g., a pulsed laser beam) and delivering the pulsed beam 113 from the source laser 112 into the interior 114 of the source container 111 to individually irradiate a target 115 within an irradiation site 116. The beam 113 can be delivered from the source laser 112 via a beam delivery system 126. The delivery system 126 may include a focusing unit 126a or cooperate with the focusing unit 126a, which includes one or more optical elements (not shown) for focusing the pulses of the beam 113 to a focal point or beam waist at or near the irradiation site 116.

[0045] EUV source 110 includes a target delivery system 117 that delivers a target 115 into the interior 114 of source container 111 to reach irradiation site 116. The target 115 travels downwards from the target delivery system 117 to irradiation site 116 in the plane of the page (in the negative x direction). At irradiation site 116, portions of the target 115 independently interact with one or more light pulses (of beam 113) to generate plasma 118, which produces EUV light, some of which is indicated by EUV light 119; however, it should be understood that EUV light radiates from plasma 118 in all directions. The radiation of light, including light 119 from plasma 118, the position of the target 115, and other data can be monitored by one or more metrology devices 150, and the information collected by the one or more metrology devices 150 can be used for the control and operation of EUV source 110.

[0046] Target 115 is or includes EUV emission target materials, such as, but not necessarily limited to, tin, lithium, xenon, or combinations thereof. Target 115 may be in the form of droplets, or alternatively, solid particles or solid particles contained within droplets. For example, elemental tin may be presented 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.

[0047] The EUV light source 110 may also include a collector 120. The collector 120 is formed with an aperture 125 to allow a beam 113 of light pulses generated by the source laser 112 to pass through the aperture 125 and reach the irradiation site 116. The collector 120 may be a near-normal incident collector mirror having an optical axis A and a reflecting surface 121. The reflecting surface 121 may be in the form of an elongated sphere (i.e., an ellipse rotating about its principal axis), such that the collector 120 has a first focal point or principal 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 (as described above) defined as a line extending between them.

[0048] Source container 111 includes an inner surface 156 that at least partially surrounds a volume in which EUV light 124 is transmitted by collector 120 from principal focal point 122 to intermediate focal point 123 along optical axis A (i.e., within the volume of a cone surrounding optical axis A) when EUV light source 110 and source container 111 are in use. Inner surface 156 may be the inner surface of liner 127 or the wall 127w of liner 127. Liner 127 may be a portion (or portions) of source container 111 that surrounds the volume in which EUV light 124 is transmitted within source container 111. Therefore, inner surface 156 can be considered as the inner surface of source container 111, or more specifically, the inner surface of liner 127. EUV light 124 from collector 120 can be output from EUV light source 110 at intermediate focal point 123 and input to devices utilizing EUV light 124, such as exposure apparatus.

[0049] To reflect EUV light 119, the collector 120 may be in the form of a multilayer mirror (MLM), with the reflective surface 121 having a hierarchical multilayer coating with alternating layers of molybdenum and silicon, and in some cases, one or more high-temperature extension barrier layers, smoothing layers, capping layers, and / or etch-stop layers. Other surface shapes besides elongated spheres may also be used for the reflective surface 121. For example, the reflective surface 121 may alternatively be in the form of a parabola rotating about its principal axis. In implementations, the reflective surface 121 may be configured to deliver a beam of EUV light 124 having an annular or other cross-section at the intermediate focus 123. In other implementations, the reflective surface 121 may utilize coatings and layers other than those described above.

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

[0051] However, collector 120 must be placed within source container 111 and close to or near plasma 118 to collect and redirect EUV light 119 and deliver EUV light 124 to intermediate focus 123. Therefore, structures within source container 111 (including collector 120) may be exposed to high-energy ions and / or particles and vapors of target material, or containing particles and vapors of target material. Target material particles, high-energy ions, and vapors are essentially debris or byproducts from photo-based evaporation or ablation processes of target material or un-laser-irradiated target material. These particles of target material and high-energy ions and vapors can contaminate the exposed reflective surface 121 of the collector. Target material particles, as well as energetic ions and vapors, can also cause physical damage and localized heating of the reflective surface 121 of collector 120.

[0052] Figure 2 This diagram illustrates the implementation of the EUV light source 210, which includes an exposure apparatus 271. The exposure apparatus 271 receives EUV light 224 generated by the EUV light source 210 and reflects it into one or more illumination mirrors 272 to illuminate a reflective pattern or mask 273. The EUV light 224 reflected from the pattern or mask 273 is further reflected and reduced by one or more reduction mirrors 274 and is then illuminated onto a substrate or wafer 275 (or one or more photosensitive layers on the substrate or wafer 275, not shown), thereby creating a patterned structure within or on the substrate or wafer 275.

[0053] Figure 3A In the yz plane with indicated directions, the source container 311 of the EUV light source (such as...) Figure 1 A graphical cross-section of various aspects of the source container 111 of the EUV light source 110 (or other source containers and EUV light sources). The downward-oriented gravity vector G in the plane of the page shows that the source container 311 can be operated at an angle relative to gravity (as shown), but is not limited to... Figure 3A The angle depicted or any specific angle. Various gas flows that can be used in source container 310 are indicated by outline arrows.

[0054] refer to Figure 3A A gas stream (such as a hydrogen (H2) gas stream) with a pressure in the range of approximately 50 to 300 Pascals (Pa) can be used within the source container 311 as a buffer gas for debris and / or vapor control. Given the need for a vacuum within the interior 314 of the source container 311 to avoid excessive absorption of gas molecules by EUV light, 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 the gas stream. Hydrogen (H2) is relatively transparent to EUV radiation with a wavelength of approximately 13.5 nm.

[0055] H2 gas can be introduced into source container 311, or into or within the liner 327 of source container 311, to slow down and guide the gas from the target ( Figure 3A (Not shown) Irradiation and high-energy fragments (ions, atoms, and clusters) of the target material generated by plasma 318 produced at the irradiation site 316. The fragments are 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 from the central aperture 325 of the collector 320 towards the irradiation site 316 where plasma 318 is repeatedly generated by a conical tube or nozzle 337, etc. This direction is opposite to the trajectory of the fragments from the irradiation site 316 towards the collector 320, so the forward flow 336 helps to reduce damage to the collector 320 caused by vapor deposition, injection, and sputtering of target material.

[0056] A transverse flow 339 can be guided along the surface of collector 320 (from an outlet not shown). So-called nozzle flows, where gas flows through multiple parallel orifices substantially perpendicular to the surface to be protected, such as nozzle flows S1 and S2, can be provided in the region of source container 311 closest to collector 120. In other regions, such as near the intermediate focus 323, protective airflow parallel to the surface to be protected, or protective airflow having a component guided parallel to the surface to be protected, can be introduced through orifices pointing in a direction having a component along or parallel to the surface to be protected. For example, airflows in the form of curtain flows, such as airflows F1, F2, F3, and F4, can be introduced to protect the inner surface 356 of source container 311 or liner 327 in the region near or closer to the intermediate focus 323.

[0057] The reverse flow 338 is one or more airflows used to prevent any material from leaving the source container 311 in the region of the intermediate focus 323. The reverse flow 338 flows from the region of the intermediate focus 323 toward the irradiation site 316, and this reverse flow 338 may also be referred to as the "intermediate focus protection" airflow 338.

[0058] A stable guide flow 340, flowing away from collector 320, can be formed primarily by a forward flow 336 together with a transverse flow 339 and nozzle flows S1 and S2 (and optional other flows not shown). An example of guide flow 340 is provided by... Figure 3A The solid curve in the figure defines the flow. This guiding flow 340 helps to contain and remove from the collector 320 the material generated from the target 315 during the generation of the plasma 318, including vapors, ions, and micro and nanoparticles. The reverse flow 341 moving from the intermediate focus 323 toward the collector 320 can be formed primarily by the reverse flow 338 together with flows such as flows F1, F2, F3, and F4 (and optionally others not shown). Examples of reverse flows are provided by... Figure 3A The dashed curve in the diagram defines the flow. The guiding flow 340 and the reverse flow 341 merge in a merging region 342 near the exhaust opening 355 within the exhaust port 333 of the liner 327. The exhaust port 333 may be connected to one or more vacuum pumps (not shown) to remove the merged flow from the source container 311. The guiding flow 340 facilitates flow into the exhaust opening 355, while target material byproducts substantially do not contact any of the inner surfaces 356(s) of the liner 327, the liner wall 327w, and / or the source container 311.

[0059] To assist in guiding the flow towards and out of the exhaust opening 355, the relative gas velocity from the nozzle flows S1 and S2 can be varied along the inner surface 356 of the liner 327 in the direction of the optical axis A' extending from the aperture 325 to the intermediate focal point 323, which is along the z-axis. Figure 3AIn this context, the relatively varying flow velocities are symbolically represented by the relatively varying lengths of the outline arrows in nozzle flows S1 and S2. Therefore, according to one aspect of this disclosure, a liner 327 is provided for a source container 311 for generating extreme ultraviolet (EUV) light. The liner 327 includes a wall 327w having an inner surface 356 extending toward a collector end 356c away from the intermediate focal end 356if of the inner surface 356. An exhaust opening 355 extends through the inner surface 356 from the collector end 356c along the inner surface 356 at a distance D along the inner surface 356 toward the intermediate focal end 356if. The distance D is substantially perpendicular to the collector end 356c. The inner surface 356 also has corresponding airflow inlets 328 (located where the arrows of nozzle flows S1 and S2 pass through the liner wall 327w). (See also the discussion below) Figure 4A and Figure 4B The corresponding airflow inlets 328 are located at a distance D along the inner surface 356 from or near the collector end 356c of the inner surface 356 to a corresponding location near or along the inner surface 356. At least some of the airflow inlets 328 are configured to supply airflow at a rate varying with their corresponding location along the distance D, in order to reduce deposition on the inner surface 356. In such cases... Figure 3A In the implementation shown, the airflow inlet 328 is configured to guide the debris flow originating from or near the master focal position 316 toward the exhaust opening 355 in the form of a guide flow 340. The velocity distributions of nozzle flow S1 and nozzle flow S2 are asymmetrical along the optical axis A'. In some embodiments, nozzle flow S1 maintains the same velocity, while the velocity of nozzle flow S2 decreases from the collector end 356c of the inner surface 356 toward a distance D or near a distance D. In some embodiments, nozzle flow S2 maintains the same velocity, while the velocity of nozzle flow S1 increases away from the collector end 356c of the inner surface 356. In some embodiments, the flow velocity of nozzle flow S1 decreases linearly from the collector end 356c of the inner surface 356 toward a distance D or near a distance D along the inner surface 356, and the flow velocity of nozzle S2 increases linearly from the collector in the direction extending from the collector end 356c of the inner surface 356.

[0060] Figure 3B It shows the relationship with Figure 3A A schematic cross-section of the same EUV light source 310, except for the flow velocities in nozzle streams S1 and S2. Figure 3A The differences are shown. In at least one embodiment, as... Figure 3BAs shown, the flow velocity along the inner surface 356 of the liner 327 does not need to be linear with respect to the distance D from the collector end 356c, but it can have a non-linear variation (or can vary non-linearly). For example, the flow velocity can increase exponentially or decrease logarithmically with respect to distance D (or take other forms). Furthermore, when the flow velocity at the exhaust opening 355 increases on the inner surface 356 opposite to the liner 327, the change in flow (i.e., in the nozzle flow S1) does not necessarily need to increase beyond the distance D from the collector end 356c of the inner surface 356 of the liner 327, but it can optionally also begin to decrease from distance D or beyond a point, such as... Figure 3B The flow rate of the nozzle flow S1 is shown in the diagram. In some embodiments, the flow rates of the nozzle flow S1 and the nozzle flow S2 can be any combination of linear and nonlinear distributions. In some cases, the flow rate of the nozzle flow S1 changes nonlinearly, and the flow rate of the nozzle flow S2 changes linearly. In some cases, the flow rates of the lower portions of the nozzle flows S1 and S2 are nonlinearly distributed, and the flow rates of the upper portions of the nozzle flows S1 and S2 are linearly distributed.

[0061] Figure 4A and Figure 4B For lining 427 (such as Figure 3A and Figure 3B Lining 327 and Figure 1 A schematic cross-sectional view of the lower portion of the lining 127. Figure 4A and Figure 4B The view is in relation to Figure 1 It is intercepted in the same xz plane, but in the orientation indicated (positive z-direction in the plane of the figure). Figure 4A and Figure 4B The view also has Figure 1 The difference also lies in the fact that the area of ​​the inner surface 456 of the lower part of the liner 427 and the cross-section of the liner are visible. Figure 4A and Figure 4B The views differ from each other in that, Figure 4B Viewed along the y-axis in the negative y-direction, the portion of the exhaust opening at 45° is visible, while Figure 4A Viewing the opposite side (half) of the inner surface 456 from the opposite direction, the portion without the exhaust opening 455 is visible.

[0062] refer to Figure 4A and Figure 4BThe liner 427 includes a plurality of airflow inlets 428 extending through the liner wall 427w. At least those airflow inlets 428 located within a first elongated region EA1 on the inner surface 456 of the liner 427 provide a flow velocity that increases with distance D along a distance D from the collector end 456c of the inner surface 456. At least those airflow inlets 428 located within a second elongated region EA2 on the inner surface 456 of the liner 427 provide a flow velocity that decreases with distance D along a distance D from the collector end 456c. As shown, the second elongated region EA2 extends from near the collector end 456c to near the nearest edge of the exhaust opening 455, and the first elongated region EA1 extends from near the collector end 456c to near a location opposite the nearest edge of the exhaust opening 455. The direction of (a plurality of) such extensions may be substantially in direction D, i.e., substantially in the direction of... Figure 1 The optical axis A is coplanar in one or more directions. In this context, "nearby" for end 456c should be understood as anything falling within a range of up to 10% of the distance D from the end 456c as close as possible to the inner surface 456. Similarly, "nearby" of the nearest edge of the exhaust opening should be understood as anything falling within a range of up to 10% of the distance D from the nearest edge of the exhaust opening 455 as close as possible to the nearest edge of the exhaust opening 455. Figure 4A and Figure 4B As shown, the volume within the inner surface 456 of the liner 427 has a cross-section that decreases from the collector end 456c of the inner surface 456 toward the intermediate focal end (not shown). The inner surface 456 of the liner 427 may also be conical, having a circular cross-section, as shown in... Figure 4A and Figure 4B And the following will be discussed Figure 5 A and Figure 6 As shown in (and other figures).

[0063] The circumferential widths of the elongated regions EA1 and EA2 need not be exactly the same as those shown in the figure. The circumferential widths of the two elongated regions EA1 and EA2 (measured in terms of the angular range around the circumference of the lining 427) can range, for example, from 20 or 30 degrees up to almost or substantially 180 degrees, and the two regions need not be identical or have a constant circumferential / angular width along the distance / direction D. Figure 3A , Figure 3B The second elongated region EA2 can be located on the opposite side of the first elongated region EA1 on the inner surface 456 (or in other words, facing the first elongated region EA1 on the inner surface 456 or positioned 180 degrees from the first elongated region EA1), such as... Figure 4A and Figure 4BAs shown in the figure. In at least one embodiment, the velocity distribution of the first elongated region EA1 is symmetrical about each other about the center line C1, and the velocity distribution of the second elongated region EA2 is symmetrical about each other about the center line C2.

[0064] Figure 5 It shows the relationship with Figure 4A and Figure 4B A similar schematic cross-section is shown, in which half of the inner surface of liner 527 is presented, but this view is different from... Figure 4A and Figure 4B It was cut off at a 90-degree angle, and in relation to Figure 3A and Figure 3B Within the same plane as the cross-section, the positive z-orientation extends upwards within the plane of the page. Figure 5 In the implementation shown, the flow rate provided by inlet 528 (represented by the bottom of the arrow extending from the inner surface 556) (the flow rate is indicated by the length of the arrow extending from the inner surface 556 of the liner 527) gradually increases or decreases linearly with distance from the collector end 556c of the inner surface 556. (For ease of viewing, only the flow at or near the left and right edges of the inner surface 556 is shown in the figure). Additionally, in Figure 5 In the liner 527, the main flow direction generated from the inlet forms a 90° angle with the inner surface 556 at the corresponding position of the corresponding inlet in the plane of the figure, as shown by the right angle RA in the lower left of the figure.

[0065] Figure 6 A cross-section of the liner 627 is shown, which is represented along... Figure 5 The cross-section taken by line 6-6 in the middle, although Figure 5 and Figure 6 The cross-sectional configurations shown can be implemented independently. For example, as Figure 7 and / or Figure 9 The liner configuration shown (discussed below) can have a shape that is parallel to the xy-plane. Figure 6 The cross-section of the lining 627 is the same as or similar to that of the lining. (Reference) Figure 6 In implementation, the gradual decrease (or increase) of the flow velocity can also be provided, for example, at a point perpendicular to the optical axis A ( Figure 1 The distance traveled within the plane of the lining around the perimeter of the inner surface, such as from Figure 4A The first slender region to Figure 4B The second slender region (or from) Figure 4B The second slender region to Figure 4A (The first slender region). In such a region Figure 6 In the implementation of the liner 627 shown, the provided flow rate originates from a position P1 opposite the exhaust opening (not visible in this view, see [link]). Figure 5Position P2, aligned with the circumference of the exhaust opening (not visible in this view, see [link]). Figure 5 The position of the circle surrounding the liner 627 gradually and linearly decreases. In the liner 627, the main flow direction generated from the inlet in this implementation forms a 90° angle with the corresponding position of the corresponding inlet on the inner surface 656 in the plane (xy plane) of the figure. For example, this is in… Figure 6 The inlet at the bottom center of the cross-section is shown, where the inlet has a main flow direction RA1 perpendicular to surface 656.

[0066] Figure 7 With similar Figure 5 A schematic cross-section illustrates another implementation of the form of the liner 727. In the liner 727, at least some of the mainstream directions generated from the inlet vary (variably deviate) from a 90° angle with the inner surface 756 at the corresponding locations of the respective inlets. Specifically, in the liner 727, the mainstream direction generated by the inlet generally varies progressively from a 90° angle with the inner surface 756 toward the exhaust opening 755 at the corresponding locations of the respective airflow inlets. In this implementation, this variation is in the plane of the figure, or in other words, within the plane containing the optical axis A ( Figure 1 Within the plane of the inner surface 756, this variation increases with increasing distance from the collector end 756c of the inner surface 756. In the implementation shown, the inlet of the collector end 756c closest to the inner surface 756 is perpendicular to the surface 756, as shown by the right angle RA2 at the lower left of the figure. The inlets farther from the collector end 756c are increasingly "bent" toward the exhaust opening 755. For example, the inlet at the upper left of the figure changes (is changed) by an angle θ1 from the right angle RA3.

[0067] Figure 8 The view is implemented in the form of liner 827, and is represented as along... Figure 7 The line 8-8 in the middle is cut off Figure 7 The cross-section, despite Figure 7 and Figure 8 The cross-sectional configurations shown can be implemented independently. For example, as Figure 5 (Discussed above) and / or Figure 9 The liner configuration shown (discussed below) can have a shape that is parallel to the xy-plane. Figure 8 The cross-section of the lining 827 is the same as or similar to that of the lining. Figure 8 In the liner 827, the variation is provided at a distance from the inner surface 856 at a 90-degree angle to the main flow direction provided by the inlet, around the periphery of the inner surface 856 of the liner 827. The variation in this implementation is in the plane of the figure (xy plane), or in other words, in the plane perpendicular to the optical axis A (…). Figure 1In the plane of the liner 827, the main flow direction provided by the inlet typically changes from a 90° angle to the inner surface 856 towards the exhaust opening at the corresponding position of the respective airflow inlet, with increasing circumferential distances from positions P1 (opposite to the circumference of the exhaust opening) and P2 (aligned with the circumference of the exhaust opening). The exhaust opening is in Figure 8 Not visible in the view, see example Figure 7 In fact, the corresponding main flow direction is in the plane of the graph (xy plane) (and usually in a parallel plane—perpendicular to) the xy plane. Figure 1 The plane of optical axis A is "bent" and deviates from the inner surface 856 by 90 degrees in the direction toward the exhaust opening. For example, this is in Figure 8 The bottom center of the cross-section is shown, and the inlet at the bottom center has a right angle RA4 towards the exhaust port (not shown, see, for example, see...). Figure 7 The exhaust opening (755) changed (or was changed) the main flow direction at angle θ2.

[0068] Figure 9 With similar Figure 5 and Figure 7 A schematic cross-sectional view illustrates another implementation of the form of liner 927. In liner 927, the flow velocity provided by the inlets increases in steps with distance from the collector end 956c of the inner surface 956, each step comprising two or more airflow inlets. Figure 9 The diagram illustrates multiple air chambers P 1-8 It can be used to provide increased and decreased flow rates, by each gas chamber P i Supplying multiple inlet groups, and each gas chamber P i Composed of multiple mass block flow controllers M 1-8 The corresponding mass block flow controller M in i Supply. Mass flow controller M 1-4 and M 5-8 Airflows GF1 and GF2 can be supplied from sources not shown in the diagram, respectively. During operation, the mass flow controller M... 1-8 It can be signaled or preset to produce a flow that increases (and decreases) with a desired distance from the collector end 956c of the inner surface 956, as described above regarding the liner 427. Figure 4A and Figure 4B Described.

[0069] Figure 10 The schematic diagram is shown in the form of liner 1027. Figure 9 The cross-section is missing. Figure 9 The airflow device outside the inner lining wall, and along Figure 9 The line in the middle is cut off at 10-10. However, Figure 9and Figure 10 The cross-sectional configurations shown can be implemented independently. For example, as Figure 5 and / or Figure 7 The liner configured as shown (as described above) can have a configuration in the xy plane similar to... Figure 10 The cross-section of the lining 1027 is the same as or similar to that of the lining. Figure 10 In the liner 1027, the flow velocity varies in steps with the circumferential position of the inner surface 1056 of the liner 1027. A flow velocity (represented by the relative length of the arrows in the figure) is provided within a first region A1 (indicated by circumferential brackets in the figure), which can correspond to Figure 4A The first elongated region EA1. Another flow rate is provided within the second region A2 (indicated by another circumferential bracket in the figure), which can correspond to... Figure 4B The second elongated region EA2. A third flow velocity is provided within the first connecting region CA1 and the second connecting region CA2. This third flow velocity is lower than the flow velocity in the first region A1 and higher than the flow velocity in the second region A2. In this embodiment, each of the four regions A1, A2, CA1, and CA2 includes seven inlets. Therefore, in Figure 10 In its implementation, the flow velocity varies in steps across the seven inlets grouped together, with a total of four steps around the circumference of the liner 1027. It should be noted that this is consistent with the previous discussion regarding... Figure 6 and Figure 8 The implementations of liner 627 and liner 827 discussed are compared, in which the flow changes from one inlet to the next.

[0070] The implementation of the inner lining wall can, for example, be... Figure 3A and Figure 3B The 327w lining is achieved in Figures 11 to 14 The cross-section of the cut is shown. Figure 11 A cross-sectional view of a portion of the liner wall 1127w is shown, in which the inlet 1128 extends through the wall 1127w in the form of successively smaller through-holes (from left to right in the figure). Using through-holes of varying diameters is one way to generate flow that varies along the position of the liner wall, such as the liner wall 1127w. Figure 12 A cross-sectional view of a portion of the inner lining wall 1227w is shown, in which the air chamber structure 1229 forms a plurality of air chambers Pn along the wall 1227w in a direction from left to right in the figure. These are fed by an airflow or stream with varying pressure (feeding is not shown, see, for example, [reference needed]). Figure 9 The continuous air chamber Pn is another method to generate a flow that varies with the position of the wall along the lining (such as the lining wall 1227w). Figure 13A cross-sectional view of a portion of the inner lining wall 1327w is shown, wherein a variable flow restriction (or flow limiter) along the direction from left to right in the figure is positioned at and / or connected to the inlet 1328. In this example, the limiter is in the form of an insert 1330 having a through-hole 1331 of varying diameter. Figure 14 A cross-sectional view of a portion of the inner liner wall 1427w is shown, in which a variable flow restriction (or flow limiter) in the form of an insert 1431 is used in conjunction with a chamber structure 1429, which creates multiple chambers Pn along the wall. The chambers are fed by an airflow or flow with varying pressure (feeding not shown, see, for example, [reference needed]). Figure 9 Combining a continuous air chamber Pn with a variable flow limiter or restrictor is another method to generate flow that varies with distance (or position or location) along the wall of the liner (such as liner wall 1427w). (Not in) Figure 13 and Figure 14 Alternative options shown include flow restrictors located upstream of inlets 1328, 1428, and flow restrictors located downstream of inlets 1328, 1428 (such as in the respective protruding nozzles, not shown).

[0071] Figure 15 This is a schematic diagram of process P100 for operating the EUV light source. (For example...) Figure 15 As shown, the process includes: allowing gas to flow from a source container and / or its inner liner wall (as shown). Figure 3A , Figure 3B 327w; Figure 4A , Figure 4B The inner surface of (427w) Figure 3A , Figure 3B 356; Figure 4A , Figure 4B The entrance at the corresponding location of (456) Figure 3A , Figure 3B 328; Figure 4A , Figure 4B (S10) flow of gas from the first elongated region (428); Figure 4A The inlet within EA1 is located at the collector end of the inner surface ( Figure 3A , Figure 3B 356c; Figure 4A , Figure 4B The distance of 456c) Figure 3A , Figure 3B The increased flow velocity (S20) from the distance D); and the gas being positioned in the second elongated region ( Figure 4BThe inlet within EA2 flows at a rate decreasing 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 cyclically until a predetermined threshold is met, such as the tin deposition thickness taking into account a specific number of pulses. Within process P100, a second elongated region extends from near the collector end to the vent opening in the inner surface ( Figure 3A , Figure 3B 355 in the middle; Figure 4A , Figure 4B Near the nearest edge of (455) and the first elongated region extends from near the collector end to near the location opposite the nearest edge of the exhaust opening (see above description). Figure 4A and Figure 4B The implementation of process P100 may include one or more of the following.

[0072] Process P100 may also include, at least in part, the use of a first plurality of flow controllers connected to an inlet located within the first elongated region. Figure 9 M 1-4 The process P100 may also include, at least in part, the use of a second plurality of flow controllers connected to an inlet located in the second elongated region to increase the flow rate of the gas. Figure 9 M 5-8 The process P100 may also include at least in part the use of a flow restrictor / limiter located at or connected to the inlet (e.g., Figure 13 Insert 1330 in the middle; Figure 14 (1430 in the middle) to make the gas flow at a reduced flow rate, these flow restrictors / limiters vary with the distance from the collector end in the first elongated region (such as... Figure 3A and Figure 3B The distance D in the process increases the restriction. Similarly, process P100 may also include at least partially using flow restrictions located at or connected to the inlet to allow the gas to flow at an increased flow rate, with these flow restrictions decreasing with distance from the collector end.

[0073] Another aspect of this disclosure addresses the problem of contamination on the inner surface of the source container of an EUV light source during transient operation. (Reference) Figure 1 When EUV light sources (such as Figure 1When the EUV light source 110 generates EUV light, a continuous target 115 is irradiated by a pulsed beam 113 of the source laser 112 to generate plasma 118 at the irradiated area 116. This first operating state of the EUV light source 110 can be referred to as "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 not desired, such as when the associated exposure apparatus moves between pattern positions on a wafer or changes from one wafer to the next. At such times, the timing of the pulses of the pulsed beam 113 can be adjusted or offset so that the pulses do not meet the target 115, and therefore the target is not irradiated by the pulse. The target simply passes through the irradiated area 116 without being irradiated and can be received by the target collector (not shown). When EUV light is not generated, this second operating state of the EUV light source can be referred to as "miss" operation or "miss mode".

[0074] In EUV light sources (such as Figure 1 In EUV light sources 110 and similar sources, transitions from miss to hit operation or from hit to miss operation can cause changes in airflow patterns (“transient” or “transient flow conditions”) within source container 111. These transitions can have negative effects. For example, during a miss-to-hit operation transition, the relatively sudden appearance of plasma 118 at irradiation site 116 may temporarily push target debris and target vapor toward the inner surface of source container 111, and / or generate eddies in the gas and plasma mixture within source container 111. These may cause target debris and vapor to come into contact and deposit on the inner surface of source container 111.

[0075] like Figure 3A and Figure 3B The above and the text shown are about Figure 3A and Figure 3B The gases flowing into source containers 111 and 311 (such as nozzle flows S1 and S2 and forward flow 336, etc.) are used to protect the internal surfaces of source containers 111 and 311 from target debris and vapor. In principle, various gas flows can be adjusted to meet the constantly changing conditions within source container 111, but the transition from miss mode to hit mode and its effects usually occur much faster than the shortest response time of any gas flow change.

[0076] Figure 16 This is a schematic cross-sectional view of a portion of the source container 1611 of an EUV light source, including related and / or connected structures that are particularly useful during transient flow conditions within the interior 1614 of the source container 1611. (See above regarding...) Figure 3A and Figure 3BThe gas discussed may flow into the interior 1614 of the source container 1611 in various forms, such as nozzle flows S1 and S2, forward flow 1636, lateral flow 1639, and reverse flow 1638, as well as other flows F1-F4 in the upper portion of the source container 1611. These, and potentially other flow patterns (not shown), cooperate to prevent or reduce the deposition of target debris and vapor on the surfaces within the source container 1611 (such as the inner surface 1656 of the source container 1611) and on the surface of the collector 1620, and to guide and / or entrain target debris and vapor, as well as plasma residues, and remove them from the source container through exhaust opening 1655 to exhaust port 1633. Figure 16 In the process, gas supply GS1, GS2 and GS3 supply gas to nozzle flows S1 and S2 and forward flow 1636, respectively.

[0077] Although, as described above, adjustments to various gas flows entering source container 1611 (such as those via gas supplies GS1, GS2, and GS3) can be made to meet the constantly changing conditions within source container 1611, the effects of such flow changes on the flow patterns within the source container appear more slowly compared to the effects caused by the transition from miss operation to hit operation or from hit operation to miss operation of the EUV source. However, as Figure 16 As shown, one or more of the flows (such as nozzle flows S1 and S2 and forward flow 1636) may be supplied to the source container 1611 via, for example, a conduit, lumen or manifold M1, M2 and / or M3 having oscillators O1, O2 and / or O3 located within or connected to the source container 1611, and the oscillators O1, O2 and / or O3 may influence the flow pattern in the source container 1611 fairly quickly.

[0078] Oscillating the oscillators O1, O2, or O3 will cause pressure oscillations within the corresponding conduit, lumen, or manifold M1, M2, or M3. These pressure oscillations can cause changes such as airflow generated at or near the outlet of the conduit, lumen, or manifold M1, M2, or M3 and injected into the interior 1614 of the source container 1611. Figure 16 The increase in kinetic energy and momentum (represented by multiple parallel arrows) occurs, while the average flow velocity from the conduit, lumen, or manifold remains unchanged. This will be referenced below. Figure 17 This was discussed further.

[0079] Oscillators O1, O2, and O3 can resemble speaker cones, such as subwoofers or other speaker cones. Such oscillators can be lightweight, strong, and highly responsive, capable of reproducing music and other sounds with high fidelity, thus initiating oscillation extremely quickly and generating pressure changes in the nearby gas. Pressure waves (or sound waves) propagate within the gas at the speed of sound. Therefore, using one or more oscillators O1, O2, and O3 in this way allows the momentum and energy of the gas generated in the source container 1611 from various flows (in this implementation, from nozzle flows S1 and S2 and the forward flow 1636) to be changed very rapidly: almost at the speed of sound, rather than at a lower rate at which the effects of increased airflow can be perceived.

[0080] For example Figure 16 As shown, the controller CTR can communicate with oscillators O1, O2, and O3, such as via corresponding associated drive signal sources DR1, DR2, and DR3. Oscillator cavities OC1, OC2, and OC3 can be used with oscillators O1, O2, and O3 to provide space and volume in which the oscillators can move sufficiently freely and interact with a sufficient amount of gas to generate the desired pressure oscillations. The controller CTR can be configured to drive one or more oscillators O1, O2, and O3 at least partially during transitions from one operating state of the source container to another. The controller CTR can also be configured to drive oscillators O1, O2, and O3 at least partially during increases or decreases in one or more gas flows entering the interior 1614 of the source container 1611. The controller CTR can also communicate with gas supplies GS1, GS2, and GS3 (e.g., Figure 16 As shown in the diagram, it is used to detect or control the increase or decrease of airflow. It should be noted that the controller CTR can take many forms, such as distributed control elements that can communicate with each other, rather than a centralized controller, and can be implemented, for example, in hardware or software or a combination thereof.

[0081] In addition to or as an alternative to the features described above, the oscillator cavity OC4 may be directly or via the conduit, chamber, or manifold M5 shown in the figure connected to one or more outlets or orifices located at or near the exhaust opening 1655 (corresponding to the positions where the dashed arrows cross into the interior of the exhaust port 1633) and / or the interior of the exhaust port 1633. Oscillation of the diaphragm or other actuators in the oscillator cavity may be generated by a drive signal source DR7, which may be controlled by a controller CTR.

[0082] The oscillation of the membrane or other actuator can generate a gas pulse sequence PT, as indicated by the dashed arrow, within or in the source container 1611 (or in the exhaust port 1633 of the source container). The pulse sequence PT... Figure 16 The dashed arrows indicate the pulsed characteristics of the flow in the pulse sequence PT. One or more pulse sequences PT are oriented at least partially along the interior of the exhaust port 1633 away from the main volume of the source container 1611. In other words, the pulse sequence PT is oriented at least partially in the direction in which the flow of gas and plasma-generating byproducts passes through the interior of the exhaust port 1633. The effect of pressure oscillations on the gas present in the oscillator cavity OC4 and manifold M5 (if present) can produce the pulse sequence PT without any net flow into the source container 1611 or its exhaust port 1633. Optionally, if desired, a (smaller) gas flow (not shown) can be supplied to the oscillator cavity OC4 or the duct, cavity, or manifold M5 to keep its inner surface clean.

[0083] The pulse sequence PT can be turned on, off, and / or altered almost instantaneously in response to changes in the drive signal from the drive signal source DR7. The pulse sequence PT can be turned on or its intensity increased to drive entrained byproducts from the gas and plasma into exhaust port 1633, facilitating the intake of gas and entrained products into exhaust opening 1655 at a greater rate when needed. This increased intake into exhaust opening 1655 can be used, for example, during and / or just before and / or after the transition of the associated EUV source from miss to hit operation and / or the transition of the associated EUV source from hit to miss operation. Specifically, the increased intake into exhaust opening 1655 can be used to prevent or reduce overshoot of target vapor and target debris into space beyond exhaust opening 1655 (above).

[0084] Figure 17 This is a schematic cross-sectional view of a conduit, cavity, or manifold forming a cavity or housing EN, which has an oscillator O mounted on the housing. The housing EN includes an orifice AP through which gas flows out of the housing. A gas feed GF into the housing EN can provide a stable flow into the housing and out through the orifice AP. (It should be noted that in...) Figure 16 In the oscillator cavity OC4 and / or conduit, cavity or manifold M5, the gas feed GF is optional. When the oscillator O is driven by the actuator with or without the flow from the gas feed GF, the pressure oscillations obtained in the housing EN can cause gas pulses to be ejected from the orifice AP.

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

[0086] The varying current supplied from the drive signal source DR to the coil CL generates pressure oscillations within the housing, resulting in an oscillating jet that is pushed out (and pulled in, depending on the net flow, if any) through the aperture AP. This variation can be in the form of a square wave or a combination of near-square waves. The residence time of the square wave at its maximum and minimum values, as well as the abrupt transition between them, can effectively increase the energy and momentum of the generated airflow, but other waveforms can also be used. Without being bound by theory, it should be assumed that the resistance on the outflowing intermittent jet from the sides of the aperture AP and from exactly outside the aperture AP slows down the radially outer portion of the intermittent jet, while the central portion is not slowed down (or experiences a delayed slowdown). This causes the jet to bend towards the form of a vortex ring with a poloidal flow (flowing in the direction of the circumference of a small circular cross-section around a ring of annular or "donut" shape). As the flow through the aperture AP repeatedly slows, stops, and / or reverses with the oscillation of the oscillator O, the vortex ring can be formed and sheared off from the aperture AP, propagating away from the aperture in the propagation direction PD. Continuous pressure oscillations can generate continuous vortex rings, such as those formed by... Figure 17 The circular arrows indicate vortex rings VR-1 to VR-4. In all or many cases, such vortex rings can carry greater momentum and energy at a greater distance from the aperture than a constant flow ejected from the same aperture. Therefore, oscillating the oscillator (typically at frequencies in the range of 40 Hz to 40000 Hz) can almost immediately increase the energy and momentum of the flow originating from or at the aperture AP, much faster than an increase in the flow rate of the gas feed GF can produce. Figure 16 In the case of a pulse sequence PT, even without net flow, vortex rings are generated from the gas within and near the aperture AP, and can carry momentum over a distance that is typically greater than the effect of normal airflow from the same aperture.

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

[0088] Figure 18This is a schematic cross-sectional view of an alternative implementation of a manifold M4 with multiple orifice APS. The manifold is fed by a gas feed GF, generating airflow through the orifice APS indicated by the parallel arrows on the left side of the figure. Multiple oscillating diaphragms in the form of multiple voice coils VC1, VC2, VC3, VC4, and VC5 provide pressure oscillations within the manifold M4. Voice coils VC1-VC5 can be driven individually, in parallel, or in a combination of individually and in parallel by one or more varying current sources DR4, DR5, and DR6. Baffles BF can be included in the manifold M4 to help guide and / or control the pressure waves generated by pressure changes caused by the oscillations of the voice coils VC1-VC5.

[0089] Figure 19 This is a flowchart of some aspects of process P1901 used to operate the EUV source, which is related to... Figures 16 to 18 The principles discussed in the text are related. For example... Figure 19 As shown, process P1901 includes a source container (S1902) through which gas flows into an EUV light source, and pressure oscillations are generated within the flowing gas, these oscillations having a frequency in the range of 40 Hz to 40 kHz. Frequency lower than 40 Hz can impart less additional momentum to the gas than intended, while at frequencies higher than 40 kHz, the effects of flow pulsation can be reduced, resulting in a more continuous flow effect and less additional momentum. The pressure oscillations can 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 container can generate vortex rings or other energy-containing flow patterns from the opening into the aperture in the source container. These energy-containing flow patterns can be generated almost instantaneously via pressure waves traveling at the speed of sound from an oscillating diaphragm or the like into the aperture in the source container. This near-instantaneous additional energy flow pattern can be used during or near the transition of the associated EUV source's operating state, such as during, just before, and / or just after, an increase in the gas flow rate into the source container; and / or during, just before, and / or just after, the transition of the EUV source from miss to hit operation and / or from hit to miss operation. Using pressure oscillations at these times can help to more quickly adjust or regulate the flow conditions within the source container to generate or maintain the desired flow pattern and prevent or reduce contamination of the surfaces within the source container.

[0090] Implementations of the present invention may be further described in the following numbered clauses: 1. A liner for a source container for extreme ultraviolet (EUV) light generation, the liner comprising: a wall having an inner surface extending toward a collector end of the inner surface away from a central focal end of the inner surface, the inner surface having an exhaust opening extending through the inner surface toward the central focal end from a distance from the collector end along the inner surface; and corresponding airflow inlets disposed at corresponding positions from near the collector end to near the distance along the inner surface; wherein at least some of the airflow inlets are configured to supply a gas flow rate varying with the corresponding position of the at least some of the airflow inlets along the distance. 2. The liner according to Clause 1, wherein the airflow inlet is configured to direct a stream of debris originating from near the focal point toward the exhaust opening. 3. The liner according to Clause 1, wherein an airflow inlet located in a first elongated region on the inner surface of the liner provides an increasing flow rate in a direction extending from the collector end, and an airflow inlet located in a second elongated region on the inner surface of the liner provides a decreasing flow rate in the direction extending from the collector end. 4. The liner according to Clause 3, wherein the second elongated region extends from near the collector end to near the nearest edge of the exhaust opening, and the first elongated region extends from near the collector end to near a position opposite to the nearest edge of the exhaust opening. 5. The liner according to Clause 3, wherein the volume within the inner surface of the liner has a cross-section that decreases from the collector end toward the intermediate focal end, and wherein the second elongated region is positioned opposite the first elongated region. 6. The liner according to Clause 3, wherein the inner surface of the liner has a conical shape, the cone having a circular cross-section that decreases from the collector end toward the intermediate focal end, and wherein the second elongated region is positioned opposite the first elongated region. 7. The liner according to Clause 3, wherein the airflow inlets are configured to supply a gas flow rate along the distance within the first elongated region, the gas flow rate increasing in steps, each step comprising two or more airflow inlets. 8. The liner according to Clause 3, wherein the airflow inlet is configured to supply a gas flow rate along the distance within the first elongated region, the gas flow rate increasing non-linearly along the direction extending from the collector end. 9. The liner according to Clause 3, wherein the at least some of the airflow inlets have corresponding flow limits, the corresponding flow limits varying with the respective locations of the at least some of the airflow inlets. 10. The liner as described in Clause 9, wherein at least some of the airflow inlets include holes through the wall of the liner, the holes varying in diameter. 11. The liner according to Clause 3, wherein at least some of the airflow inlets are supplied by two or more corresponding flow controllers in two or more corresponding groups, the two or more flow controllers being configured to supply flow at a corresponding rate according to the corresponding position of the corresponding group. 12. The liner according to Clause 1 further includes a plurality of gas supply chambers, wherein at least some of the airflow inlets are each connected to one of the plurality of gas supply chambers. 13. The liner as described in Clause 12, wherein each of the plurality of gas supply chambers is supplied via a respective flow controller. 14. The liner according to Clause 1, wherein the respective airflow inlet guides the flow in the respective main flow direction, and the respective main flow direction forms a 90° angle with the inner surface at the respective location of the respective airflow inlet. 15. The liner according to Clause 1, wherein the respective airflow inlet guides the flow in a respective main flow direction, the respective main flow direction having an angle that varies with the inner surface at the respective location of the respective airflow inlet. 16. A method of operating an extreme ultraviolet (EUV) light source, the method comprising: flowing a gas into a source container of the EUV light source; and generating pressure oscillations within the flowing gas, the pressure oscillations having a frequency in the range of 40 Hz to 40 kHz. 17. The method according to Clause 16, wherein generating the pressure oscillation within the flowing gas comprises: generating oscillation in a membrane, the membrane being in direct or indirect contact with the flowing gas. 18. The method according to Clause 17, wherein the membrane is connected to a coil, the coil is connected to a supply of varying current and is positioned in a magnetic field. 19. The method according to Clause 16, wherein causing the gas to flow comprises: causing a forward-flowing gas to flow. 20. The method according to Clause 16, wherein causing the gas to flow comprises: causing the gas to flow from an inlet located at a corresponding position along an inner surface of the source container, the inner surface extending from a collector end of the inner surface toward a central focal end of the inner surface. 21. The method according to Clause 16, wherein causing the gas to flow comprises: changing the flow rate, and wherein generating the pressure oscillation within the gas comprises: generating a pressure change while changing the flow rate of the gas. 22. The method according to Clause 16, wherein causing the gas to flow comprises: increasing the flow rate of the gas, and wherein generating the pressure oscillation within the gas comprises: generating the pressure oscillation during or just before increasing the flow rate of the gas. 23. The method according to Clause 16, wherein generating the pressure oscillation within the flowing gas comprises: generating the pressure oscillation within the flowing gas at least in part during a transition from one operating state of the source container to another operating state of the source container. 24. The method according to Clause 16, wherein generating the pressure oscillation within the flowing gas comprises: generating the pressure oscillation within the flowing gas at least in part during the transition from a miss operation of the source container to a hit operation of the source container. 25. The method according to Clause 16, wherein generating the pressure oscillation within the flowing gas comprises: generating the pressure oscillation within the flowing gas at least in part during the transition from a hit operation to a miss operation of the source container. 26. An EUV source comprising: a source container; a gas conduit, cavity, or manifold connected to the source container for delivering gas from a gas source into the interior of the source container; and an oscillator positioned within a portion of the gas conduit, cavity, or manifold for providing pressure oscillation within the gas in the gas conduit, cavity, or manifold. 27. The EUV source according to Clause 26, wherein the gas source is configured to increase and decrease the gas flow into the interior of the source container, and further includes a controller connected to the oscillator, wherein the controller is configured to cause the oscillator to oscillate at least partially during the transition from one operating state of the source container to another operating state of the source container. 28. The EUV source according to Clause 26, wherein the gas source is configured to increase and decrease the gas flow into the interior of the source container, and further includes a controller connected to the oscillator, wherein the controller is configured to cause the oscillator to oscillate at least partially during the increase or decrease of the gas flow into the interior of the source container. 29. A method of operating an EUV light source, the method comprising: passing a flow of gas and plasma-generated byproducts through the interior of an exhaust port of a source container of the EUV source; and generating one or more pulse sequences of gas and / or plasma-generated gaseous byproducts in the exhaust port and / or within the interior of the exhaust port, the pulse sequences being oriented at least partially in the direction of the flow. 30. An EUV source comprising: a source container including an exhaust port; and an oscillator configured to generate pressure oscillations propagating through an aperture into the exhaust port; wherein the aperture is configured to generate a pulse sequence, the pulse sequence being oriented at least partially in a direction entering or along the exhaust port remotely from the main volume of the source container.

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

Claims

1. A liner for a source container for extreme ultraviolet (EUV) light generation, said liner comprising: The wall has an inner surface that extends toward a collector end of the inner surface away from the central focal end of the inner surface, and the inner surface has an exhaust opening that extends through the inner surface from the collector end along the inner surface toward the central focal end. as well as The corresponding airflow inlet is located at a corresponding position from near the collector end to near the distance along the inner surface; At least some of the airflow inlets are configured to supply a gas flow rate that varies with the corresponding position of the at least some of the airflow inlets along the distance.

2. The liner of claim 1, wherein the airflow inlet is configured to direct debris flow originating from near the focal point toward the exhaust opening.

3. The liner of claim 1, wherein an airflow inlet located in a first elongated region on the inner surface of the liner provides an increasing flow rate in a direction extending from the collector end, and an airflow inlet located in a second elongated region on the inner surface of the liner provides a decreasing flow rate in the direction extending from the collector end.

4. The liner of claim 3, wherein the second elongated region extends from near the collector end to near the nearest edge of the vent opening, and the first elongated region extends from near the collector end to near a position opposite to the nearest edge of the vent opening.

5. The liner of claim 3, wherein the volume within the inner surface of the liner has a cross-section that decreases from the collector end toward the intermediate focal end, and wherein the second elongated region is positioned opposite the first elongated region.

6. The liner of claim 3, wherein the inner surface of the liner has a conical shape, the cone having a circular cross-section that decreases from the collector end toward the intermediate focal end, and wherein the second elongated region is positioned opposite the first elongated region.

7. The liner of claim 3, wherein the airflow inlets are configured to supply a gas flow rate along the distance within the first elongated region, the gas flow rate increasing in steps, each step comprising two or more airflow inlets.

8. The liner of claim 3, wherein the airflow inlet is configured to supply a gas flow rate along the distance within the first elongated region, the gas flow rate increasing non-linearly along the direction extending from the collector end.

9. The liner of claim 3, wherein the at least some airflow inlets have corresponding flow limits, the corresponding flow limits varying with the corresponding positions of the at least some airflow inlets.

10. The liner of claim 9, wherein at least some of the airflow inlets comprise holes through the wall of the liner, the holes varying in diameter.

11. The liner of claim 3, wherein at least some of the airflow inlets are supplied by two or more corresponding flow controllers in two or more corresponding groups, the two or more flow controllers being configured to supply flow at a corresponding rate according to the corresponding position of the corresponding group.

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

13. The liner of claim 12, wherein each of the plurality of gas supply chambers is supplied via a respective flow controller.

14. The liner of claim 1, wherein the respective airflow inlet guides the flow in the respective main flow direction, the respective main flow direction forming a 90° angle with the inner surface at the respective location of the respective airflow inlet.

15. The liner of claim 1, wherein the respective airflow inlet guides the flow in a respective main flow direction, the respective main flow direction having an angle that varies with the inner surface at the respective location of the respective airflow inlet.

16. A method for operating an extreme ultraviolet (EUV) light source, the method comprising: The gas flows into the source container of the EUV light source; as well as Pressure oscillations are generated within the flowing gas, the pressure oscillations having a frequency in the range of 40 Hz to 40 kHz.

17. The method of claim 16, wherein generating the pressure oscillation within the flowing gas comprises: Oscillations are generated in the membrane, which is in direct or indirect contact with the flowing gas.

18. The method of claim 17, wherein the membrane is connected to a coil, the coil is connected to a supply of varying current and is positioned in a magnetic field.

19. The method of claim 16, wherein causing the gas to flow comprises: To make the gas flow in the forward direction.

20. The method of claim 16, wherein causing the gas to flow comprises: Gas is allowed to flow from an inlet located at a corresponding position on the inner surface of the source container, which extends from the collector end of the inner surface toward the central focal end of the inner surface.

21. The method of claim 16, wherein causing the gas to flow comprises: Changing the flow rate, wherein generating the pressure oscillation within the gas comprises: generating a pressure change while changing the flow rate of the gas.

22. The method of claim 16, wherein causing the gas to flow comprises: Increasing the flow rate of the gas, and wherein generating the pressure oscillation within the gas comprises generating the pressure oscillation during or just before increasing the flow rate of the gas.

23. The method of claim 16, wherein generating the pressure oscillation within the flowing gas comprises: The pressure oscillation is generated in the flowing gas at least in part during the transition from one operating state of the source container to another operating state of the source container.

24. The method of claim 16, wherein generating the pressure oscillation within the flowing gas comprises: The pressure oscillation is generated in the flowing gas at least in part during the transition from a miss operation to a hit operation of the source container.

25. The method of claim 16, wherein generating the pressure oscillation within the flowing gas comprises: The pressure oscillation is generated in the flowing gas at least in part during the transition from a hit operation to a miss operation of the source container.

26. An EUV source, comprising: Source container; A gas conduit, cavity, or manifold connected to the source container to deliver gas from a gas source into the interior of the source container; An oscillator, positioned within a portion of the gas conduit, the cavity, or the manifold, for providing pressure oscillation within the gas in the gas conduit, the cavity, or the manifold.

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

28. The EUV source of claim 26, wherein the gas source is configured to increase and decrease the gas flow into the interior of the source container, and further comprises a controller connected to the oscillator, wherein the controller is configured to cause the oscillator to oscillate at least partially during the increase or decrease of the gas flow into the interior of the source container.

29. A method of operating an EUV light source, the method comprising: The flow of byproducts generated by gas and plasma is passed through the interior of the exhaust port of the EUV source container; as well as One or more pulse sequences of gas and / or one or more pulse sequences of gaseous byproducts generated by plasma are generated in and / or within the exhaust port, the pulse sequences being oriented at least partially in the direction of the flow.

30. An EUV source, comprising: Source container, the source container including an exhaust port; as well as An oscillator configured to generate pressure oscillations that propagate through an aperture into the exhaust port; The aperture is configured to generate a pulse sequence, which is at least partially oriented in a direction into or along an exhaust port away from the main volume of the source container.

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