Robotic arm for cleaning structure surface in chamber

Abstract

An apparatus for cleaning a surface of a component within an extreme ultraviolet (EUV) lithography vessel, the apparatus includes: a robotic arm comprising a movable portion and arranged relative to the lithography vessel such that its movable portion has access to the component surface; and a surface wave plasma (SWP) generator at the movable portion of the robotic arm, the SWP generator configured to generate a surface wave plasma in a region proximate to the movable portion, and, when the movable portion is within a cleaning distance from the component surface, the generated surface wave plasma removes debris from the component surface during cleaning mode.

Description

ROBOTIC ARM FOR CLEANING STRUCTURE SURFACE IN CHAMBERCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to US Application No. 63 / 603,762, filed November 29, 2023, titled ROBOTIC ARM FOR CLEANING STRUCTURE SURFACE IN CHAMBER, which is incorporated herein by reference in its entirety.TECHNICAL FIELD

[0002] The disclosed subject matter relates to a system and method for cleaning debris from a surface of a structure within a chamber of an extreme ultraviolet (EUV) light source using a robotic arm and a surface wave plasma (SWP) generator.BACKGROUND

[0003] Extreme ultraviolet (EUV) light, for example, electromagnetic radiation having wavelengths of around 50 nanometers (nm) or less (also sometimes referred to as soft x-rays), and including light at a wavelength near 13.5 nm (for example, in a range of about 13.36 nm - 13.65 nm at 50% power), can be used in photolithography processes to produce extremely small features in substrates, for example, silicon wafers.

[0004] Methods to produce EUV light include, but are not necessarily limited to, converting a material that has an element, for example, xenon, lithium, or tin, with an emission line in the EUV range in a plasma state. In one such method, often termed laser produced plasma (“LPP”), the required plasma can be produced by irradiating a target material, for example, in the form of a droplet, plate, tape, stream, or cluster of material, with an amplified light beam. For this process, the plasma is typically produced in a sealed vessel, for example, a vacuum chamber, and monitored using various types of metrology equipment.SUMMARY

[0005] As described herein, a method and an apparatus for cleaning a surface of a component with debris disposed thereon is provided.

[0006] In some general aspects, an apparatus for cleaning a surface of a component within an extreme ultraviolet (EUV) lithography vessel is provided. The apparatus includes: a robotic arm comprising a movable portion and arranged relative to the lithography vessel such that its movable portion has access to the component surface; and a surface wave plasma (SWP) generator at the movable portion of the robotic arm. The SWP generator is configured to generate a surface wave plasma in a region proximate to the movable portion, and, when the movable portion is within a cleaning distance of zero or greater from the component surface, the generated surface wave plasma removes debris from the component surface during cleaning mode. In some embodiments, theapparatus is provided for cleaning a surface of a component within an exposure tool, such as a scanner or a stepper.

[0007] Implementations can include one or more of the following features. For example, an EUV lithography system includes an EUV light source vessel that defines a light source chamber or a scanner that defines an optics chamber. The apparatus also includes a base to which the robotic arm is attached, the base having a geometry that fits within a base opening that receives an EUV light collector. The component includes a conical liner positioned between the base opening and an exit opening, the liner including an exposed surface that, when installed, faces an optical path between the base opening and the exit opening. The light source chamber includes an interaction region that aligns with a primary focus of an EUV light collector, and, in operating mode, the EUV light collector can be fixed in a base opening and the interaction region receives target material that are converted to plasma that produces EUV light. The debris can be deposited on the component surface due to the production of EUV light. The target material can include at least one of tin, lead, and antimony.

[0008] The apparatus also includes a base to which the robotic arm is attached, the base mounted on a side of a conical liner positioned between the base opening and an exit opening, the base configured to introduce the robotic arm and the SWP generator into the light source chamber or the optics chamber during cleaning mode and to remove the robotic arm and the SWP generator from the chamber prior to EUV operating mode. The component can remain in the EUV lithography vessel or the exposure tool while the generated surface wave plasma removes debris from the component surface during cleaning mode. The apparatus can be configured to be removably introduced into the EUV lithography vessel or the exposure tool without needing to remove the component. The robotic arm can be connected to an arm controller configured to control motion of the robotic arm and the SWP generator. The SWP generator includes an inner electrical conductor extending along an axial direction and a dielectric insulator outside of the inner electrical conductor and extending along the axial direction. In cleaning mode, when the dielectric insulator is within the cleaning distance of the component surface, the generated surface wave plasma can remove debris from the component surface. In cleaning mode, the axial direction can be adjacent to, distant to, parallel to, or askew to the component surface when the dielectric insulator is within the cleaning distance of the component surface and configured to remove debris from the component surface. In cleaning mode, the SWP generator can radiate electromagnetic energy, which transforms a material that is present adjacent the SWP generator from a first state into a plasma state that includes plasma particles, and the plasma particles and the component surface form a waveguide for the propagation of the electromagnetic energy. In cleaning mode, part of the guided electromagnetic energy can continue to transform material present at another location along the waveguide into the plasma state that includes plasma particles. In cleaning mode, at least some of the plasma particles can be free radicals and ions of the material, such that the plasma particles come in contact with the debris on the component surface. TheSWP generator can radiate electromagnetic energy at a microwave frequency. The material present adjacent the SWP generator can be in a gas state.

[0009] In some embodiments, the component surface is an optical surface configured, during operating mode, to operationally interact with electromagnetic radiation. In some embodiments, the component surface is a non-optical surface configured, during operating mode, to not operationally interact with electromagnetic radiation. The EUV lithography vessel can be an EUV lithography exposure vessel that defines an exposure chamber that, in operating mode receives a wafer. The component can be a reflective optical element configured to, in operating mode, direct EUV light to or from a mask.

[0010] In other general aspects, an extreme ultraviolet (EUV) lithography apparatus includes: a lithography vessel defining a chamber; a component of the chamber, the component including a surface exposed to debris during operating mode; and an apparatus for cleaning the exposed surface of the component during a cleaning mode without having to remove the component from the chamber. The apparatus includes: a robotic arm including a movable portion and arranged relative to the lithography vessel such that its movable portion has access to the component surface during the cleaning mode; and a surface wave plasma (SWP) generator at the movable portion of the robotic arm. The SWP generator is configured to generate, during the cleaning mode, a surface wave plasma in a region proximate to the movable portion, and, when the movable portion is within a cleaning distance of zero or greater from the component surface, the generated surface wave plasma removes debris from the component surface during the cleaning mode.

[0011] In other general aspects, a method of cleaning a component surface in a chamber of an extreme ultraviolet (EUV) lithography vessel is performed. The method includes: halting an operating mode of the EUV lithography vessel during which the component surface is exposed to debris; and beginning cleaning mode once operating mode is halted. Cleaning mode includes: robotically maneuvering a surface wave plasma (SWP) generator placed at a movable portion of a robotic arm into the chamber of the EUV lithography vessel; robotically maneuvering the SWP generator to within a cleaning distance of zero or greater from the component surface; and generating surface wave plasma at the component surface with the SWP generator to thereby remove debris from the component surface.

[0012] The details of one or more implementations are set forth in the accompanying drawings and the description below. Other features will be apparent from the description and drawings, and from the claims.DRAWING DESCRIPTION

[0013] The accompanying drawings, which are incorporated herein and form part of the specification, illustrate the present disclosure and, together with the description, further serve toexplain the principles of the present disclosure and to enable a person skilled in the relevant art(s) to make and use implementations described herein.

[0014] Fig. 1A is a schematic block diagram of a cleaning apparatus configured to clean debris off a surface of a component of a chamber defined in a vessel, the cleaning apparatus including a robotic arm and a surface wave plasma (SWP) generator;

[0015] Fig. IB is a schematic block diagram of a close-up view of the cleaning apparatus according to some embodiments of the present disclosure;

[0016] Fig. 1C is a schematic block diagram of a close-up view of the cleaning apparatus according to some embodiments of the present disclosure;

[0017] Fig. ID is a flow chart of a procedure for controlling the robotic arm according to some embodiments of the present disclosure;

[0018] Fig. 2A is a side cross-sectional view of an implementation of the SWP generator of Figs. 1A- 1C, in which the SWP generator has a linear geometry, and showing, in cleaning mode, creation of guided electromagnetic energy (a waveguide) along the surface;

[0019] Fig. 2B is a side cross-sectional view of the SWP generator of Fig. 2A showing cleaning mode at a later time;

[0020] Fig. 2C is a top cross-sectional view of the SWP generator of Figs. 2A and 2B taken along an 2C-2C plane and showing a power source configured to supply current to the SWP generator;

[0021] Figs. 3A-3C are schematic cross-sectional close-up views showing operation of the SWP generator according to some embodiments of the present disclosure, in which Fig. 3A shows the production of the surface-wave plasma relative to the exposed surface, Fig. 3B shows plasma particles coming in contact with debris on the exposed surface, and Fig. 3C shows the plasma particles chemically reacting with the deposited particles of the debris to form a new chemical that is released from the exposed surface;

[0022] Fig. 4A is a side cross-sectional view of an implementation of the cleaning apparatus according to some embodiments of the present disclosure, in which robotic arm is defined by a first shortened length and a head unit, the SWP generator, and the metrology unit are located close to an opening of the chamber;

[0023] Fig. 4B is a side cross-sectional view of the implementation of the cleaning apparatus according to some embodiments of the present disclosure, in which the robotic arm is defined by a second extended length and the head unit, the SWP generator, and the metrology unit are farther away from the opening of the chamber;

[0024] Fig. 5 is a side cross-sectional view of an implementation of the cleaning apparatus, in which the cleaning apparatus is mounted in an opening of the vessel in place of an EUV light collector;

[0025] Fig. 6 is a side cross-sectional view of the vessel in which the EUV light collector is mounted in the opening instead of the cleaning apparatus;

[0026] Fig. 7 is a flow chart of a procedure for cleaning the exposed surface of a component of the chamber according to some embodiments of the present disclosure;

[0027] Fig. 8 is a flow chart of a procedure for installing the cleaning apparatus in the vessel, cleaning the exposed surface of the component of the chamber, and uninstalling the cleaning apparatus from the vessel;

[0028] Fig. 9A is a perspective view of an implementation of the cleaning apparatus according to some embodiments of the present disclosure, in which the robotic arm is in a first shortened length and positioned closer to the base unit;

[0029] Fig. 9B is a plan view of the implementation of the cleaning apparatus according to some embodiments of the present disclosure, in which the robotic arm is in a first shortened length and positioned close to the base unit;

[0030] Fig. 9C is a perspective view of the implementation of Fig. 9A, in which the robotic arm is in a second extended length and positioned farther from the base unit; and

[0031] Fig. 10 is a flow chart of a cleaning procedure can be employed to use the cleaning apparatus for cleaning a surface of the component within the vessel.

[0032] The features of the present disclosure will become more apparent from the detailed description set forth below when taken in conjunction with the drawings, in which like reference characters identify corresponding elements throughout. In the drawings, like reference numbers generally indicate identical, functionally similar, and / or structurally similar elements. Additionally, generally, the left-most digit(s) of a reference number identifies the drawing in which the reference number first appears. Unless otherwise indicated, the drawings provided throughout the disclosure should not be interpreted as to-scale drawings.DESCRIPTION

[0033] Referring to Fig. 1A, as described herein, an apparatus 100 for cleaning a surface 160 of a component 165 with debris 156 disposed thereon is provided. The component 165 is in a chamber 130 of a vessel 131 of an EUV light source that produces EUV light 137 when in operation, as discussed in more detail below. In some embodiments, the chamber 130 refers to an optics chamber of an exposure tool, such as a photolithography exposure apparatus (scanner or a stepper). In the EUV light source chamber 130, debris 156, such as, for example, debris from target matter, can deposit on the component 165 during an operating mode (or use) of the EUV light source (with or without production of EUV light 137). This debris 156 builds up and eventually the component 165 becomes unusable or inefficient.

[0034] While cleaning the debris 156 from the component 165 can be accomplished with chemical and abrasive methods, such methods create other problematic issues, such as the unwanted generation of particulates or the provision of a corrosive agent within the EUV light source. Additionally, these other methods can require long periods of time with the EUV light source offline for the cleaning.Another option to remove the debris 156 from the component 165 is to replace the debris-deposited component 165 or parts of the debris-deposited component 165. These approaches, however, are expensive, time consuming, and subject to supply limitations.

[0035] The apparatus 100 includes a robotic arm 152 and a surface-wave plasma (SWP) generator 101 installed thereon. The robotic arm 152 includes a movable portion 152d and the robotic arm 152 is arranged relative to the vessel 131 such that the movable portion 152d has access to the surface 160 of the component 165. In some implementations, the SWP generator 101 is at the movable portion 152d of the robotic arm 152. The SWP generator 101 is configured to generate surface wave plasma 120 in a region proximate to the movable portion 152d. The surface wave plasma 120 includes plasma particles containing free radicals and ions of the material already present near the surface 160 such that the plasma particles come in contact with the debris 156 on the surface 160. The plasma particles can include free radicals and ions of hydrogen. One example of a simple free radical of hydrogen is a single hydrogen element with an unpaired valence electron (H*). When the movable portion 152d is within a cleaning distance De from the surface 160, the generated plasma particles, which is further discussed below, due to surface wave plasma 120 removes the debris 156 from the surface 160 during a cleaning mode. It is noted that, in some implementations, De can be zero and the SWP generator 101 can touch the surface 160. In some implementations, the cleaning mode occurs at times other than when operating mode occurs. The cleaning distance De is depicted schematically in Fig. 1A, but, in practice or real use, the cleaning distance De can be larger or smaller than this depiction.

[0036] In one implementation, as shown in Fig. 1A, the SWP generator 101 is provided on a head unit 154 of the robotic arm 152, the head unit 154 positioned at the movable portion 152d. The robotic arm 152 is configured to move the SWP generator 101 such that the robotic arm 152 is positioned to allow a surface 160 of the component 165 to be cleaned by the SWP generator 101. The combination of the robotic arm 152 and the SWP generator 101 can perform in-situ cleaning while the component 165 remains within an EUV chamber 130 rather than requiring disassembly or removal of the component 165 from the EUV chamber 130 for cleaning or replacement.

[0037] Specifically, the cleaning apparatus 100 is designed to clean debris 156 off of an surface 160 of the component 165 of the EUV chamber 130 in a vessel 131. The cleaning apparatus 100 includes the SWP generator 101 that can be positioned near the surface 160 of the component 165 (in particular such that the movable portion 152d is within the cleaning distance De of the surface 160). Utilizing the SWP generator 101, any debris 156 on the exposed surface 160 of the component 165 can be cleaned through generation of plasma particles (such as H*) due to the surface wave plasma 120 that removes the debris 156 during cleaning mode.

[0038] Cleaning mode can include maneuvering the SWP generator 101 placed at the movable portion 152d of the robotic arm 152 into the vessel 131 such that the SWP generator 101 is in the chamber 130, robotically maneuvering the SWP generator 101 to within the cleaning distance De, which can be zero as mentioned above, from the surface 160. If the cleaning distance De is greaterthan zero, then the generation of the plasma particles such as H* is provided as diffusion. If the cleaning distance is zero, then the SWP generator 101 generates the surface wave plasma 120 at the exposed surface 160 with the SWP generator 101 to remove the debris 156 from the exposed surface 160.

[0039] As discussed in detail below with reference to Figs. 2A, 2B, and 3A-3C, the surface wave plasma 120 can be self-guiding such that, when in cleaning mode, it creates a guided electromagnetic energy (a waveguide) along the surface 160 to transform material present at a location along the waveguide near the surface 160 into a plasma state that includes the plasma particles. The surface wave plasma 120 includes plasma particles containing free radicals and ions of the material already present near the surface 160 such that the plasma particles come in contact with the debris 156 on the exposed surface 160 and clean the debris 156 from the exposed surface 160.

[0040] In some implementations, the cleaning apparatus 100 includes a base unit 150, the robotic arm 152 attached to the base unit 150, an arm controller 153 configured to control operation of the robotic arm 152, a head unit 154 attached to the robotic arm 152 at the movable portion 152d, and the SWP generator 101 connected to the head unit 154. Each of these elements of the cleaning apparatus 100 is discussed below.

[0041] In some implementations, the cleaning apparatus 100 is configured to be removably positioned in the chamber 130. The cleaning apparatus 100 can be removably introduced into the vessel 131 without needing to remove the component 165 from the chamber 130.

[0042] In some implementations, as shown in Fig. 1A, the vessel 131 is an EUV light source vessel. In these implementations, the chamber 130 is a light source chamber defined within the EUV light source vessel. Specifically, the vessel 131 can be an EUV light source vessel that defines a light source chamber. The vessel 131, as a light source chamber, can include an interaction region 140 that aligns with a primary focus of an EUV light collector (discussed below regarding Fig. 5). In operation, the vessel 131 can have the EUV light collector fixed in a base opening and the interaction region 140 receives targets 135 that can be converted to plasma 136 that produces the EUV light 137. The debris 156 can therefore be deposited on the surface 160 due to the production of the EUV light 137. In general, the targets 135 are provided at the region 140 within the chamber 130. The targets135 include matter that emits EUV light 137 when the matter is converted into a light-emitting plasma136 upon interaction with an energy pulse 138 (such as a pulse of an amplified light beam or laser beam) in the region 140. The EUV light 137 and light-emitting plasma 136 shown in Fig. 1A can be produced from a prior target 135 in the region 140 that has interacted with a prior energy pulse.

[0043] The debris 156 is at least partially produced from leftover or remaining target matter 155 in the chamber 130. In particular, the leftover or remaining target matter 155 can be target matter within the target 135 that is not converted into the light-emitting plasma in the region 140 and / or the leftover or remaining target matter 155 can be produced from light-emitting plasma that reverts back into target matter 155. The process of generating the EUV light 137 relies on converting the matter inmany targets 135 into light-emitting plasma 136, and thus a large amount of remaining or leftover target matter 155 can be produced in the process. Different phases of the remaining target matter 155 tend to deposit on surfaces of various objects inside the chamber 130. The remaining target matter 155 that remains or is leftover can travel through the chamber 130 and coat various objects such as walls, optical elements, and components within the chamber 130. As shown in Fig. 1A, target matter 155 has deposited onto the surface 160 of the component 165 to form the debris 156. The debris 156 that forms on the surfaces of these objects (including the exposed surface 160 of the component 165) can include vapor residue, ions, particles, and / or clusters of matter formed from the remaining target matter 155.

[0044] The debris 156 severely impairs the performance of the EUV light source by blocking the EUV light 137 and / or by contaminating the components of or within the chamber 130. The debris 156 forms a coating on the surface 160 that effectively blocks the surface 160. Thus, if the surface 160 is an optical surface that is meant to interact with light in the chamber 130, its efficiency will drop as it becomes coated with debris 156. As another example, if the surface 160 is a non-optical surface (that does not interact with light), then the debris 156 coating the surface 160 can cause other serious problems within the chamber 130. The debris 156 can cause the surface 160 and the component 165 to heat up, which can lead to the debris 156 being ejected from the surface 160 and onto other objects within the chamber 130. The debris 156 can cause other problems that lead to a reduction in the production of EUV light 137. For example, the debris 156 can be flaked off, dropped off, spit off, or dripped off the surface 160. In summary, the presence of such debris 156 reduces the performance of the surfaces within the chamber 130 and reduces the overall efficiency of the EUV light source and production of EUV light 137. As discussed below, if the target 135 includes molten metal of tin, then tin particles, clusters of tin, tin residue, or tin ions can accumulate on (or coat) one or more components 165 within the chamber 130.

[0045] The debris 156 can be produced from materials other than the remaining target matter 155 that are present within the chamber 130. For example, the debris 156 can include carbon.

[0046] As illustrated in the implementation of Fig. 1A, the base unit 150 is installed into the vessel 131 of the chamber 130. The base unit 150 is configured to fixedly attach the robotic arm 152 to the vessel 131. The base unit 150, to which the robotic arm 152 is attached, can be configured to cooperate with one or more preexisting portions 129 of the vessel 131 for ease of installation, and accuracy and consistency of placement. For example, as discussed further below, the base unit 150 can have a geometry that fits with a base opening, defined at the portion 129 of the vessel 131, that would otherwise receive another device (such as an EUV light collector) during operating mode. Such a design enables the use of a preexisting mounting method by which the cleaning apparatus 100 is provided to the vessel 131. As illustrated in Fig. 1A, the base unit 150 allows the cleaning apparatus 100 to be positioned consistently and reliably because of the geometry of the cleaning apparatus 100. This geometry is specific for the use in the fixed and secured location that is provided for other parts,such as the EUV light collector, which can have a collector exchange preconfigured. In other implementations, the base unit 150 is configured to fit totally within the vessel 131 (for example entirely within the chamber 130) or at a position on the vessel 131 other than at the portion 129.

[0047] As mentioned, the base unit 150 also includes the arm controller 153. The arm controller 153 can include one or more mechanical devices. The mechanical devices can include a direct current (DC) motor, an alternating current (AC) motor, an induction motor, an actuation motor, a linear screw drive, a belt drive, a stepper motor, bearing housings, a timing belt assembly, motor assemblies, a rotary bottom plate, a vessel install mechanism, and a connector to the robotic arm 152.

[0048] The robotic arm 152, while contemplated and illustrated as attached to the base unit 150, can be used independently from the base unit 150. For example, the robotic arm 150 can be placed within the vessel 131 in any location provided that the mechanical movement is feasible.

[0049] The robotic arm 152 can use the arm controller 153, which uses one or more mechanical devices such as motors. The motors can be linear stepper motors. The arm controller 153 can be configured to control the motors for moving the attached robotic arm 152, the head unit 154, and the SWP generator 101. For example, the arm controller 153 can include relays to remote controls, remote controls, and motors. The robotic arm 152 can be moved by the arm controller 153 to manipulate the head unit 154 and the SWP generator 101 such that the SWP generator 101 can be specifically positioned as needed, such as into an area to be cleaned. The arm controller 153 can receive and utilize information from a metrology unit 128 that is mounted on the head unit 154 or another part of the apparatus 100 to measure and map any portions of the vessel 131, the chamber 130, the component 165, or any other unit within the vessel 131 to specifically locate debris 156.

[0050] The arm controller 153 can also use known or programmed locations or coordinates to move the head unit 154 and the SWP generator 101 into a particular position. The robotic arm 152 (under control of the arm controller 153) is configured to position the SWP generator 101 within the cleaning distance De to the surface 160 to enable efficient cleaning of the surface 160. For example, the cleaning distance De can be within ± 0.50 millimeters (mm) from a pre-programmed location, thus allowing precise removal of debris 156 from the surface 160. For example, the cleaning distance De can be relative to a location on the surface 160 that has been previously mapped (and stored for access by the arm controller 153).

[0051] The head unit 154 can include the metrology unit 128. The metrology unit 128 can measure or estimate location information of the head unit 154 in all directions at all times. The metrology unit 128 can provide such location information to the processor 159, as illustrated in Fig. 1A. The metrology unit 128 can include a magnetic linear encoder configured to provide feedback to the mechanical devices (motors) of the arm controller 153 to thereby enable tracking of linear movement of the head unit 154. The metrology unit 128 can include a magnetic sensing system that can provide location information to an accuracy as good as 0.50 mm, as good as 0. 1 mm, or even as good as 0.01 mm. The metrology unit 128 can use a non-contact, wear-free sensing system that can have highresistance to dirt and vibrations. In some embodiments, the metrology unit 128 refers to a camera, an x-ray fluorescence measurement device, a spectrometry device, or any suitable detector.

[0052] The process 170 of controlling the robotic arm using the arm controller 153 and the processor is illustrated in Fig. ID. In Fig. ID, the processor can provide instructions to the arm controller in order to move the head unit and the SWP generator . In operation 171, the metrology unit measures or estimates one or more of the location of the head unit and the location of the debris. The metrology unit can locate the head unit and the SWP generator on the robotic arm. In operation 172, the metrology unit provides the location of the head unit and / or the debris to the processor . The metrology unit can also estimate a relative distance between the SWP generator 101 and the debris 156 or the surface 160. In operation 173, a new location, such as a location of debris, is stored in a memory and accessed by the processor. The arm controller, via the processor , can, in response to queries as to a position of the head unit, move the robotic arm. In operation 174, the location of the head unit and the SWP generator is moved by the arm controller based on instructions from the processor and then the SWP generator removes the debris.

[0053] In some embodiments, the metrology unit 128 is configured to measure or estimate while the SWP generator 101 is removing the debris 156. For example, SWP generator 101 can operate to remove the debris 156 until the metrology unit 128 determines that the amount debris 156 on the surface 160 has dropped below a pre-determined level. In some embodiments, the metrology unit 128 measures again after a set time period and then the processor 129 decides whether the process 170 continues with the next operation or returns to the operation 172 to make a loop and continue removing the debris 156.

[0054] The component 165 can remain in the vessel 131 while the cleaning apparatus 100 is operating in cleaning mode. In some implementations, the component 165 to be cleaned is a conical liner 580, such as illustrated in Fig. 5, a cold flow module (CFM) liner 431, such as shown in Figs. 4A and 4B, or other types of liners that define a pathway for the EUV light 137 from the primary focus defined in the interaction region 140 to a secondary focus and that contain the EUV light 137 within this pathway. For example, a conical liner 580 can be positioned between the base unit 150 (element 550 in Fig. 5) and an exit opening (where the secondary focus SF is defined as shown in Fig. 5) with the conical liner 580 including an exposed inner surface that, when installed, faces an optical path of the EUV light 137 between the base opening (that receives the base unit 150 / 550) and the exit opening.

[0055] In some implementations, the surface 160 of the component 165 to be cleaned is an optical surface that is configured, during operating mode, to operationally interact with electromagnetic radiation. In other implementations, such as discussed with respect to the conical liner 580 of Fig. 5, the surface 160 of the component 165 is a non-optical surface that is configured, during operating mode, to not operationally interact with electromagnetic radiation.

[0056] In some implementations, the surface 160 of the component 165 to be cleaned is an optical surface that is configured, during exposure mode, to project light to a photomask or a wafer.

[0057] The exposed surface 160 can be electrically conducting and electrically grounded. As mentioned above, in some implementations, the chamber 130 is defined within the vessel 131 of an EUV light source. An example of an EUV light source is shown in Fig. 5. The component 165 can be entirely within the vessel 131 (as shown in Fig. 1A and the vessel 531 of Fig. 5). Or, the component 165 can make up a part of the vessel 131 so that it includes the exposed surface 160 that faces the chamber 130. Thus, for example, the component 165 can be a wall 165w of the vessel 131 and the surface 160 can be an inner surface 160w of the wall. The cleaning apparatus 100 operates to clean the debris 156 off the exposed surface 160 without having to separate (such as remove or detach) the component 165 from the chamber 130. Stated alternatively, the cleaning can take place in-situ.

[0058] While a single cleaning apparatus 100 and a single component 165 are shown in Fig. 1A, there can be more than one cleaning apparatus 100 associated with a single component 165 and there can be more than one component 165 that is being cleaned with the cleaning apparatus 100. Moreover, while not shown in Fig. 1A for clarity, other devices and modules can be inside the chamber 130 or fixed to the vessel 131.

[0059] Referring to Fig. IB, in some implementations, the head unit 154 of the cleaning apparatus 100 has a metrology unit 128 that includes one or more measurement devices such as an x-ray fluorescence (XRF) device 157 and a camera 158. The XRF device 157 and / or the camera 158 can be used to measure and monitor the amount of debris 156 on the surface 160 and the amount of debris 156 that has been removed from the surface 160. The XRF device 157 and / or the camera 158 can additionally or alternatively monitor and map one or more surfaces of the vessel 131 and / or the surface 160. The camera 158 can include be a visible light or infrared (IF) light camera. The XRF device 157 and / or the camera 158 can be mounted anywhere on the cleaning apparatus 100. For example, in the implementation shown, the XRF device 157 and / or the camera 158 are mounted on the head unit 154. In this way, the XRF device 157 and the camera 158 are configured to measure a thickness or mass of the debris 156 before, during, and / or after the SWP generator 101 is used, and visual confirmation from the camera 158 can be achieved at a similar position. In some embodiments, the XRF device 157 and / or the camera 158 are mounted on a different head unit or a different robotic arm than those of SWP generator.

[0060] In other implementations, as shown in Fig. 1C, the XRF device 157 is mounted on the metrology unit 128 while the camera 158 is mounted on the base unit 150. In this way, the XRF device 157 is configured to measure the thickness of the debris 156 and confirmation of cleaning (reduction of the thickness of the debris 156), while the camera 158 is configured to provide visualization of the entirety of the interior of the vessel 131. The XRF device 157 can be configured to learn the configuration of component 165. The XRF device 157 can then keep the head unit 154 and / or the SWP generator 101 at a fixed distance from the component 165. The XRF device 157 canalso be configured to measure the amount of debris 156 accumulated on the exposed surface 160. In other implementations, the metrology unit 128 includes a device, instead of the XRF device 157, that utilizes other methods besides x-ray fluorescence, as needed. For example, the amount of debris can be measured by the XRF device 157 or a substitute device providing similar information using, for example, laser sensors, spectroscopy, laser-induced breakdown spectroscopy (LIBS), interferometry, resistance, or capacitance.

[0061] Referring to Figs. 2A-2C, in some implementations, the SWP generator 101 is an antenna, having a conductive structure (the conducting element 102) that transmits electromagnetic radiation or waves. As shown in the implementation of Figs. 2A-2C, the SWP generator 101 has a linear geometry that includes an inner electrical conductor or conducting element 102 such as a rod or a wire extending along a local axial path Z_C (which is into and out of the page of Figs. 2A and 2B) and a coaxial dielectric insulator 103 outside the conducting element 102, the insulator 103 extending as well along the axial path Z_C. When used in cleaning mode, the axial direction can be adjacent, distant, parallel, or askew to a surface 160 (extending along the X_C, Z_C plane) of the component 165 when the coaxial dielectric insulator 103 is within the cleaning distance De of the surface 160 of the component 165 and configured to remove debris 156 from the surface 160 of the component 165.

[0062] In the illustrated implementation, the insulator 103 surrounds the conducting element 102. A space or a gap 114 between the conducting element 102 and the insulator 103 can be filled with, for example, air. The gap 114 ensures that any plasma that is produced (as discussed below) is well separated from the conducting element 102 so that there is a reduced or zero change of arcing between the plasma and the conducting element 102. In order to ensure that the gap 114 is maintained, ends 202a, 202b (see Fig. 2C) of the conducting element 102 and insulator 103 can be sealed (such as joined by, for example brazing). The gap 114 also helps move the produced plasma away from the conducting element 102 so that a suitable density of the plasma is maintained.

[0063] In one specific non-limiting example, a diameter of the conducting element 102 (taken in the X_C, Y_C plane) is a value in the range of about 1 -4 millimeters (mm) and an inner diameter of the insulator 103 (in the X_C, Y_C plane) is a value in the range of about 5-8 mm. The insulator 103 in this illustration is close to or is in contact with the exposed surface 160. Current is flowed through the conducting element 102, as discussed in more detail with reference to Fig. 2C.

[0064] As shown in the close-up views of Figs. 2A and 2B, the SWP generator 101 generates electromagnetic energy or radiation 106 along the axial path Z_C when current is flowed through the conducting element 102. The electromagnetic radiation 106 can be at a microwave frequency and thus, in this case, the SWP generator 101 generates microwave radiation. And, this electromagnetic radiation 106 transforms material 132 that is present in the chamber 130 from a first state of matter (for example, gas, vapor, or liquid) into a plasma state of matter (or simply referred to as the “surface wave plasma”), which is labeled as 120. The material 132 is shown in the first state of matter in Fig. 1A. The material 132 can be transformed by, for example, ionization. The plasma 120 that isproduced from the interaction of the electromagnetic radiation 106 and the material 132 is referred to as a surface wave plasma 120. The surface wave plasma 120 includes, among other materials, plasma particles 133.

[0065] The surface wave plasma 120 is a self-guided plasma that naturally spreads over the exposed surface 160 of the component 165 and naturally forms a waveguide 121 (which can be considered a lossy waveguide). Thus, the plasma 120 is created by the electromagnetic radiation 106 (interacting with the material 132), but the plasma 120 also reflects and guides this same electromagnetic radiation 106 along the surface (the exposed surface 160 of the component 165). The waveguide 121 is the region or space between the surface wave plasma 120 and the exposed surface 160 of the component 165.

[0066] For example, Fig. 2B shows the state of the surface wave plasma 120 at a later time than the time shown in Fig. 2A, noting that the surface wave plasma 120 extends into and out of the page (along the Z_C direction) as well as the X_C direction. In Fig. 2B, the guided electromagnetic radiation 106 has transformed the material 132 present at a location along the +X_C direction along the exposed surface 160 relative to the location in Fig. 2A, and therefore, the surface wave plasma 120 has spread along the exposed surface 160 of the component 165 away from the SWP generator 101 along the +X_C direction. The previously-created surface wave plasma is represented as 120o and the previously-created waveguide is represented as 121o in Fig. 2B. There are fewer plasma particles 133 in the older surface wave plasma 120o because many of the plasma particles 133 in the older surface wave plasma 120o have been used to etch the debris 156 from the exposed surface 160 of the component 165. Beyond the time snapshot of Fig. 2B, the radiation 106 continues to travel along the exposed surface 160 within the waveguide 121 along the +X_C direction.

[0067] It should be noted that the electromagnetic radiation 106 is created in all of the open spaces that surround the SWP generator 101, and not just to the right of the SWP generator 101 in the plane of the page shown in Fig. 2A. The electromagnetic radiation 106 is therefore created to the left of the SWP generator 101 as well, and the surface wave plasma 120 can be created to the left of the SWP generator 101. Some or most of the surface wave plasma 120 created to the left of the SWP generator 101 can, depending on the geometry of the surface 160 and surrounding components, be blocked from traveling by other objects placed near the SWP generator 101 and the exposed surface 160.

[0068] As noted above, the views of Figs. 2A and 2B are taken along the X_C, Y_C plane but it should be noted that the SWP generator 101 extends into and out of the page (along the Z_C direction as shown in Fig. 2C) and therefore electromagnetic radiation 106 (and therefore the surface wave plasma 120) is generated in locations along the SWP generator 101 at locations into and out of the page, as shown in Fig. 2C. Additionally, the surface 160 extends along the Z_C direction.

[0069] The radiation 106 travels along the exposed surface 160 a distance that depends on the amount of power supplied to the conducting element 102, a pressure of the material 132, and a composition of the material 132. Moreover, the rate at which the debris 156 is removed (via etching)from the exposed surface 160 is directly related to a pressure at which the chamber 130 is held. Thus, for example, a lower pressure in the chamber 130 correlates to a higher rate of etching and a higher pressure in the chamber 130 correlates to a lower rate of etching. The travel length of the radiation 106 can be proportional to the pressure provided or maintained.

[0070] The chamber 130 is not a hospitable environment for the SWP generator 101. In particular, the SWP generator 101 is exposed to all of the possible debris materials (including targets 135) that can coat the components 165 (and surfaces 160 of the components 165) of the chamber 130. Moreover, the SWP generator 101 can also be exposed to the EUV light 137 that is produced when the targets 135 are converted into the light-emitting plasma 136 during the operating mode. Additionally, the SWP generator 101 can also be exposed to light at other wavelengths (such as, for example, infrared radiation) that is produced when targets 135 are converted into the light -emitting plasma 136 during operating mode. Such infrared radiation can produce heat, which can cause the SWP generator 101 to heat up to a temperature that is greater than an acceptable operating temperature.

[0071] Because of this, the cleaning apparatus 100 can be moved out of the vessel 131 during operating mode. The cleaning apparatus 100, as mentioned above, can include the base unit 150. In implementations disclosed herein, the base unit 150 can be configured to be installed in or on the vessel 131. In one embodiment, the base unit 150 can be configured to be installed in place of an EUV light collector, which will be discussed further with Fig. 5.

[0072] As shown in more detail in Figs. 2A-2C, the SWP generator 101 is positioned on or close enough to the exposed surface 160 (for example, such that the movable portion 152d is within the cleaning distance De from the surface 160) to enable efficient cleaning of the surface 160.

[0073] As shown in the close-up views of Figs. 2A-2C, and as discussed above, the electromagnetic radiation 106 can also transform material 132 that is present in the chamber 130 to produce a surface wave plasma 120 that naturally spreads over the exposed surface 160.

[0074] The material 132 that is converted into the surface wave plasma 120 can be present within the chamber 130. This means that the material 132 already exists within the chamber 130 independently of the operation of the cleaning apparatus 100. In some implementations, the chamber 130 is initially manufactured without introducing material 132; then, material 132 is subsequently introduced prior to and / or during operation of chamber 130. The material 132 is then present in the chamber 130 during operation of the chamber 130 (for example, during the operating mode). Thus, the material 132 does not need to be transported into the chamber 130 from outside the chamber 130 prior to operation of the cleaning apparatus 100 because the material 132 is already present in the chamber 130 for operation of the chamber 130. The material 132 can be transported into the chamber 130 via a fluid port in the vessel 131. For example, the material 132 can be supplied within the chamber 130 for other purposes during operation of the EUV light source such as to provide a fluid flow pattern or to provide a buffer over surfaces within the chamber 130.

[0075] Referring to Fig. 3A, the plasma state of the material 132 is referred to as the surface wave plasma 320A (which corresponds to the surface wave plasma 120). The surface wave plasma 320A includes plasma particles 333 of the material 132, and these plasma particles 333 are quite chemically reactive. For example, the plasma particles 333 can include free radicals and / or ions of the material 132. The material 132 can be in a gas state prior to being transformed by the surface wave plasma 120. The SWP generator 101 is positioned such that the plasma particles 333 come in contact with the debris 156 on an exposed surface 360 (which can be the exposed surface 160). In particular, as discussed above, the SWP generator 101 is positioned such that the movable portion 152d is within the cleaning distance De from the surface 360) to enable efficient cleaning of the surface 360.

[0076] As shown in Fig. 3B, the plasma particles 333 are attracted to the particles of the debris 156 and they travel toward the debris 156, leaving behind depleted surface wave plasma 320B. The plasma particles 333 chemically react with the deposited particles of the debris 156 to form a new chemical 334 (as shown in Fig. 3C). As more and more of the plasma particles 333 travel toward the debris 156 to form the new chemical 334, they leave behind even more depleted surface wave plasma 320C (as shown in Fig. 3C). The new chemical 334 is released from the exposed surface 360. For example, the new chemical 334 can be in a gaseous state, and thus becomes released from the exposed surface 360 upon formation. This new chemical 334, which is in the gaseous state, can then be pumped out of the chamber 130 by way of a removal apparatus 322.

[0077] The surface wave plasma 120 (or 320A, 320B, 320C) includes plasma particles containing free radicals and ions of the material (such as hydrogen) already present near the surface 160 such that the plasma particles come in contact with the debris 156 on the exposed surface 160 and is distinguished from the light-emitting plasma 136 (see Fig. 1) as follows. The light-emitting plasma 136 is produced from the interaction between the target 135 and the energy pulse 138 (which can be a pulse of the amplified light beam) during the operating mode. The light-emitting plasma 136 can be considered to be a highly-ionized plasma with electron temperatures of several tens of electron volts (eV). Moreover, the light-emitting plasma 136 of the target 135 is what produces the EUV light 137. By contrast, the surface wave plasma 120 (or 320A, 320B, 320C) and the plasma particles 333 are created from the material 132 that is found inside the chamber 130. Neither the material 132 nor the plasma particles 333 contributes to the production of the EUV light 137 that is output from the light source. Moreover, the plasma particles 333 are not produced from any interaction of the material 132 with the energy pulse (or amplified light beam) 138.

[0078] The cleaning apparatus 100 can be configured to operate (that is remove the debris 156 from the exposed surface 160 / 161) even though it is exposed to molecular hydrogen, which is present in the chamber 130. Moreover, the cleaning apparatus 100 can be configured to operate without the use of or presence of oxygen; that is, oxygen is not needed or required in order for the cleaning apparatus 100 to operate and / or perform its functions. An implementation of the cleaning apparatus 100 can be configured to operate in a vacuum with hydrogen or argon.

[0079] In some implementations, the cleaning apparatus 100 is designed to remove the debris 156 from the exposed surface 160 of the component 165 without requiring the removal of the component 165 from the chamber 130. In some implementations, the operation of the component 165 within the chamber 130 that contribute to the production of the EUV light 137 and / or maintain the operation of the chamber 120 (referred to as the operating mode) need not be halted in order to clean the exposed surfaces 160 of those components 165 (referred to as the cleaning mode). This means that cleaning mode can take place during operating mode. Thus, the operation of the EUV light source does not need to be halted or shut down in order for the cleaning apparatus 100 to clean the exposed surface 160.

[0080] The cleaning apparatus 100 is able to remove most if not all of the debris 156 from the surfaces 160. The cleaning apparatus 100 operates to prevent the ejection of the debris 156 (such as by spitting, flaking, or dripping) from the exposed surface 160. Moreover, the cleaning apparatus 100 is more reliable thermally, less complex, and cheaper than previous designs that required heating of components within the chamber 130 in order to reduce the detrimental effect of the target matter 155. The cleaning apparatus 100 does not heat the component 165, and thus spitting is mitigated or avoided completely. In particular, the temperature of the chamber 130 overall is lower and the component 165 is not heated, and the overall temperature of the component 165 is lower than the melting point of the debris 156. Moreover, the consumption of the material 132 is reduced or minimized because any plasma particles 333 that do not interact with the target matter 155 in the debris 156 will reform into material 132.

[0081] In some implementations, the chamber 130 is maintained at a vacuum during operating mode, that is, at a pressure below atmospheric pressure. For example, the chamber 130 can be at a low pressure of between about 0.5 Torr (T) to about 1.5 T (for example, at 1 T). A particular pressure may be suitable for the most efficient generation of EUV light 137. The cleaning apparatus 100 can be configured to operate in a cleaning mode environment of the chamber 130, and the cleaning mode environment can be different from the operating environment. In this case, the cleaning apparatus 100 is configured to operate in the environment required during cleaning mode. In some implementations, the cleaning apparatus 100 is configured to operate in vacuum with hydrogen or argon.

[0082] As discussed above, the plasma particles 333 can include free radicals and / or ions of the material 132. Because of their reactive nature, free radicals are used to remove a substance (such as the debris 156) from an object such as the exposed surface 160. The free radicals remove the debris 156 by, for example, etching, reacting with, and / or combusting the target matter 155 that forms the debris 156. It is noted that ions, which can be part of the plasma particles 333 along with the free radicals as noted above, can also assist in the removal of debris 156 by, for example, etching, reacting with, and / or combusting the target matter 155 that forms the debris 156.

[0083] The target 135 (see Fig. 1A) can be, for example, a droplet of liquid or molten metal, a portion of a liquid stream, solid particles or clusters, solid particles contained within liquid droplets, aform of target material, or solid particles contained within a portion of a liquid stream. The target 135 can be any material that emits EUV light 137 when in the plasma state. That is, the target 135 is a substance that, when in the plasma state, has an emission line in the EUV range. For example, the target 135 can include water, tin, lithium, and / or xenon. The target 135 can be a target mixture that includes the target matter 155 as well as impurities such as non-target particles (which do not contribute to the production of the EUV light 137). As an example, the target 135 can be the element tin, which can be used as pure tin (Sn); as a tin compound such as SnBr4, SnBr2, SnH4; as a tin alloy, such as tin-gallium alloys, tin-indium alloys, tin-indium-gallium alloys; or any combination of these alloys. In the situation in which there are no impurities, the target 135 includes only the remaining target matter 155.

[0084] In some implementations in which the target 135 includes tin (Sn), the target matter 155 that forms the debris 156 includes tin particles (for example, tin or tin oxide). One of the materials 132 present and permitted within the chamber 130 is molecular hydrogen (H2). In this case, the plasma particles 333 (Figs. 3A-3C) can be produced from the molecular hydrogen. The plasma particles 333 can include free radicals and ions of hydrogen. One example of a simple free radical of hydrogen is a single hydrogen element with an unpaired valence electron (H*). The chemical process that transpires due to the operation of the cleaning apparatus 100 is represented by the following chemical formula: H2 (g) <- 2 H* (g), where g indicates that the chemical is in the gaseous state.

[0085] The generated free radicals H* of the hydrogen bond with the tin particles in the debris 156 and form the new chemical 334, which in this example, is called tin hydride (SnH4). The tin hydride is then released from the exposed surface 360. This chemical process is represented by the following chemical formula:4 H* (g) + Sn (s) <- SnFE (g), where s indicates that the chemical is in the solid state.

[0086] In this way, the coating formed from the debris 156 is etched off or removed from the exposed surface 360 at a rate of at least 0.02 nanometers (nm) per minute (min) and as much as 200 nm / min. If the rate is smaller than 0.02 nm / min, in some instances, the debris removal process takes too much time, decreasing the productivity. If the rate is greater than 200 nm / min, the power consumption increases without significantly efficiency enhancement. The total surface area of the region of the exposed surface 360 that can be etched depends on the length of the SWP generator 101, the radius of the conducting element 102, and the current or power supplied to the conducting element 102. The total surface area extends beyond the immediate vicinity of the SWP generator 101 because the surface wave plasma 120 travels along the exposed surface 160.

[0087] As discussed above, the distance that the surface wave plasma 120 travels depends at least on the power delivered to the conducting element 102. In one example in which the power supplied to the conducting element 102 is in the range of 80 watts (W) to 2 kilowatts (kW), the range of distance (that the surface wave plasma 120 travels) can be 2-30 cm. It can be desirable to achieve largerdistances (that is, the surface wave plasma 120 travels larger distances) because then the surface wave plasma 120 can reach more regions of the surface 160. There is a tradeoff between the distance and the required power delivered to the conducting element 102. Moreover, it may not always be beneficial to deliver more power to the conducting element 102 and thus more reasonable distances (for example, a few centimeters) may be more practical.

[0088] Additionally, the plasma particles 333 are created as close as possible to the exposed surface 360, or close enough that fluid flows within the chamber 130 move the plasma particles 333 quickly across the exposed surface 360 before the plasma particles 333 recombine or revert back into the material 132. This is important because hydrogen radicals H* (and other free radicals) are short lived and tend to recombine to reform molecular hydrogen. The cleaning apparatus 100 is designed to enable the plasma particles 333 to have a chance to react with the target matter 155 of the debris 156 before these plasma particles 333 have a chance to recombine with each other to reform the material 132, and this permits the cleaning of the exposed surface 360 without having to remove the component 165 from the chamber 130. It is noted that the distance the surface wave plasma 120 travels can also decrease past a certain power level. For example, at powers up to 600W, the distance can increase, but at powers above 600W, the distance can decrease.

[0089] H* is not the only free radical or ion produced by the cleaning apparatus 100 from molecular hydrogen H2. There are many other free radicals and ions that can be formed from molecular hydrogen H2 due to the operation of the cleaning apparatus 100. These other free radicals and ions are plasma particles 333 as well. For example, Deuteron H2+ and Triton H3+ can also react with tin and form gaseous tin hydrides, although they are not dominant.

[0090] The inner conducting element 102 can be made of any suitable conducting material such as copper and copper alloys. The conducting element 102 is connected to terminals, and a transmitter supplies an electric current to the terminals, such that the conducting element 102 radiates the energy from the current as electromagnetic waves or radiation (for example, microwave radiation). The coaxial dielectric insulator 103 is not electrically conductive. For example, a suitable dielectric is a ceramic such as aluminum nitride, boron nitride, silicon carbide, aluminum oxide, boron carbide, and other composite ceramics. In other implementations, the dielectric can be glass, porcelain, mica, polyethylene, quartz, or sapphire.

[0091] Fig. 2C shows a cross-sectional top view of an implementation 200 of the cleaning apparatus 100 of Fig. 2A taken along the 2C-2C plane (with the local Y_C axis into the page). The SWP generator 201 includes an inner conducting element 202 electrically connected to ground 204, which is encased by a dielectric insulator 203 (such as alumina) and a gap 214, which can be filled with air. The SWP generator 201 is positioned on the exposed surface 260 of the component 265. The inner conducting element 202 is coupled to a power source 208 configured to supply current to the inner conducting element 202. The current that is supplied to the inner conducting element 202 can be in the microwave range. Microwave frequencies are electromagnetic wave frequencies that lie in therange extending from around 100 megahertz (MHz) to 3 gigahertz (GHz). The power supplied to the inner conducting element 202 can be on the order of 60-2000 watts (W) and the amount of power supplied to the inner conducting element 202 can directly impact the reach or extent of the surface wave plasma 120.

[0092] While the SWP generator 101 of the cleaning apparatus 200 has a linear geometry (that extends generally along an axial direction, which can change), in other implementations, the cleaning apparatus can be configured as a strip or a button geometry.

[0093] In one implementation, the electric power supplied to the inner conducting element 202 is on the order of several or tens of kilowatts (kW). The inner conducting element 202 can have a diameter of less than i inch. The microwave frequency can be about 300 MHz to 3 GHz and the electric power supplied to the inner conducting element 202 can be about 0.1-3 kW (or on the order of a few hundred watts). The chamber 130 can be held at about pressure within a range of 1 pascal (Pa) to 140 Pa. The rate of removal of the debris 156 from the exposed surface 160 can be at least 0.1 nanometers (nm) / minute (min), or about 0.2 nm / min across the entire surface 160.

[0094] Additionally, a control apparatus 212 can communicate with the cleaning apparatus 200 and the power source 208 to thereby control the operation of the SWP generator 201. For example, the control apparatus 212 can send a signal to the power source 208 to provide current to the inner conducting element 202. The control apparatus 212 can include one or more modules. The various modules of the control apparatus 212 can be free-standing modules in that data between the modules is not transferred from module to module. Or, one or more of the modules within the control apparatus 212 can communicate with each other. The modules within the control apparatus 212 can be colocated or separated from each other physically.

[0095] The control apparatus 212 can include memory, which can be read-only memory and / or random access memory. Storage devices suitable for tangibly embodying computer program instructions and data include all forms of non-volatile memory, including, by way of example, semiconductor memory devices, such as EPROM, EEPROM, and flash memory devices; magnetic disks such as internal hard disks and removable disks; magneto -optical disks; and CD-ROM disks. The control apparatus 212 can also include one or more input devices (such as a keyboard, touch screen, microphone, mouse, hand-held input device, etc.) and one or more output devices (such as a speaker or a monitor).

[0096] The control apparatus 212 can include one or more programmable processors, and one or more computer program products tangibly embodied in a machine -readable storage device for execution by a programmable processor. The one or more programmable processors can each execute a program of instructions to perform desired functions by operating on input data and generating appropriate output. Generally, the processor receives instructions and data from memory. Any of the foregoing may be supplemented by, or incorporated in, specially designed microprocessors or ASICs (application-specific integrated circuits).

[0097] Each of the modules within the control apparatus 212 can be a set of computer program products executed by one or more processors. Moreover, any of the modules can access data stored within the memory. Connections between controllers / features / modules within the control apparatus 212 and between controllers / features / modules within the control apparatus 212 and components within the cleaning apparatus 100, 200 can be wired or wireless.

[0098] Referring to Figs. 4A and 4B, an EUV light source implementation 470 is illustrated. The EUV light source 470 can include a vessel 431, such as a cold flow module (CFM), and an implementation 429 of a portion 129, which is an opening 429 in the vessel 431 where a collector (not shown) would have been located.

[0099] For the purposes of using an implementation 400 of the cleaning apparatus 100, the collector (not shown) has been removed and replaced with the cleaning apparatus 400 in the opening 429. In one implementation, the base unit 450 of the cleaning apparatus 400 is configured to fit within the opening 429, which is in an area of the vessel 431 where the collector is configured to fit.

[0100] For example, the collector can be removed from the EUV light source 470 using a collector swap mechanism, and the base unit 450 can be configured to utilize the collector swap mechanism for installation of the cleaning apparatus 400 into the vacated location of the collector. Thus, the cleaning apparatus 400 can utilize preexisting mechanisms, such as vessel install mechanisms like a collector exchange mechanism, for installation in order to simplify the cleaning process. The cleaning apparatus 400 includes a robotic arm 452 including sub-arms 456-1, 456-2 (visible in Fig. 4B), an arm controller 453, a head unit 454, a metrology unit 428 with optionally an x-ray fluorescence (XRF) device 457 and a camera 458 attached to the base unit 450, and a SWP generator 401 attached to the head unit 454. The base unit 450 can have a geometry that fits within the opening 429 that would otherwise receive the collector (not shown).

[0101] Also shown in Fig. 4A, the robotic arm 452 is defined by a first length 460 in which the robotic arm 452 is shortened and the sub-arm 456-2 is adjacent the sub-arm 456-1. At this length, the head unit 454, SWP generator 401, and the metrology unit 428 are located closer to the opening 429. The robotic arm 452 can be configured with the first length 460 for loading or unloading the cleaning apparatus 400 from the vessel 431, or for cleaning areas of the vessel 431 that are closer in proximity to the opening 400.

[0102] On the other hand, in Fig. 4B (as a contrast to Fig. 4A), the robotic arm 452 is extended and reaches a second length 465 by the telescopic linear motion of the sub-arm 456-2 relative to the subarm 456-1. The robotic arm 452 can be configured with the second length 465 for reaching into the vessel 431 such that the head unit 454, the SWP generator 401 , and the metrology unit 528 with the optionally included XRF device 457 and / or camera 458 can reach deeper into the vessel 431 with an extended robotic arm 452 and the head unit 454, the SWP generator 401, and the metrology unit 528 located near the movable portion 552d of the robotic arm 455 farther from the opening 429 to provide access to portions of the vessel 431 at a farther distance from the opening.

[0103] The robotic arm 452 is designed to enable the head unit 454, the SWP generator 401, and the metrology unit 428 with the optionally included XRF device 457 and camera 458 to have access to any portion of the vessel 431 at almost any location. In particular, the robotic arm 452 and the head unit 454 are movable to almost any angle or distance from the opening 429, as needed, by the relative movement between the two sub-arms 456-1, 456-2 each controlled by a linear stepper motor. For example, a linear rail for a telescopic lift mechanism can be provided with a first section 453 allowing sub-arm 456-2 to move relative to sub-arm 456-1 to allow SWP generator 401 to be telescopically lifted and manipulated along a linear rail.

[0104] In Fig. 5, the base unit 550 and the collector 577, as discussed above but not shown, are simplified in the illustration. As shown in Fig. 5, the vessel 531 of the EUV light source 570 has mechanisms in place, such as a collector swap mechanism, that allows for uniformity when the collector 577 or the cleaning apparatus 500 is installed in and attached to a liner 580 of the vessel 531. For example, the collector 577, when rendered inoperable, can be replaced with a different collector 577 using a collector swap mechanism. A collector swap mechanism can include a slide or a latch type of mechanism by which the collector 577 can be provided with accuracy of alignment based upon the mechanism engineered into the vessel 531. Likewise, the collector swap mechanism can be used to remove the collector 577 and to provide the cleaning apparatus 500 in the location where the collector 577 had vacated. To this end, guide rails 551 can be configured to cooperate with the vessel 531 and the liner 580 to be guided into the position where the collector 577 was previously installed. The guide rails 551 can include mechanical fasteners, grooves, protrusions, etc. to allow for fitment within the liner 580 of the vessel 131.

[0105] The flow module 576 includes the liner 580, which is a conical liner for this implementation, having an interior surface 581 that encloses, at least in part, the volumetric interior 575 in which, when the EUV light source 570 is in use, EUV light (not shown in Fig. 5) is transmitted by the collector 577 from the primary focus PF to the intermediate or secondary focus SF along the optical axis OA. The liner 580 can have a conical shape such that the cross-section in the XY plane is circular or even elliptical.

[0106] As shown in Fig. 5, an implementation 531 of the vessel 131 in a simplified schematic representation is a part of an EUV light source 570. The EUV light source 570 of Fig. 5 is represented in a simplified schematic view and only some components of the EUV light source 570 are displayed. Fig. 5 is shown in an X-Z plane of the vessel 531, with the positive X direction aligned with an upward direction in the plane of the page, and the positive Z direction extending to the right in the plane of the page, where the Z axis is aligned with an optical axis OA of the vessel 531.

[0107] The vessel 531 defines the chamber 530 in which the flow module 576 is defined. The flow module 576 is positioned inside the chamber 530 of the vessel 531. In this schematic view, targets, which can be tin droplets, are provided by a target delivery system 571 and the targets interact withone or more energy pulses such as pulses of an amplified light beam to produce a plasma that produces the EUV light.

[0108] The EUV light source 570 also includes a collector 577. The collector 577 can be a nearnormal incidence collector mirror having an optical axis OA and a reflective surface 579. In implementations, the reflective surface 579 can be configured to deliver a beam of the EUV light having circular-shaped, a ring-shaped, or other cross section at the intermediate focus IF. In other implementations, the reflective surface 579 can utilize coatings and layers other than or in addition to those described above. The reflective surface 579 is configured to reflect light in the EUV wavelength range. Additionally, the reflective surface 579 can be configured to absorb, diffuse, or block light outside the EUV wavelength range.

[0109] For the purposes of using an implementation 500 of the cleaning apparatus 100, the collector 577 can be removed and replaced with the cleaning apparatus 500. In one implementation, the base unit 550 of the cleaning apparatus 500 can be configured to fit within the area of the vessel 531 that the collector 577 was configured to fit. For example, the collector 577 can be removed from the vessel 531 using a collector swap mechanism, and the base unit 550 can be configured to utilize the collector swap mechanism (by way of the guide rails 551) for installation of the cleaning apparatus 500 into the vacated location of the collector 577. Thus, the cleaning apparatus 500 can utilize preexisting mechanisms for installation in order to simplify the cleaning process. The cleaning apparatus 500 can have the base unit 550 to which a robotic arm 552, an arm controller 553, a head unit 554, and a SWP generator 501 are attached, and the base unit 550 can have a geometry that fits with an opening that would otherwise receive the collector 577.

[0110] In Fig. 5, the base unit 550 and the collector 577 are simplified in the illustration, but can have mechanisms in place, such as a collector swap mechanism, that allows for uniformity when the collector 577 or the cleaning apparatus 500 are installed in the vessel 531.[oni] The liner 580 can include an exhaust opening 582 that opens into the interior 575 and forms a pathway out of the interior 575 for debris that is created within the interior 575. Such debris that is ejected or directed out of the interior 575 through the exhaust opening 582 can be collected by an external debris handling apparatus. The interior 575 can accommodate gas flows that can be used as a buffer gas for debris and / or vapor during operating mode. In some implementations, hydrogen (H2) is used as a hydrogen gas flow within the interior 575 since hydrogen is relatively transparent to EUV radiation having a wavelength of about 13.5 nanometers (nm). Hydrogen gas can be introduced into the interior 575 to slow down and / or guide energetic debris (such as ions, atoms, and clusters) of target material created by irradiation of the targets and by the resulting plasma. The debris (which is highly energetic) is slowed down (or de-energized) by collisions with the gas molecules (the H2 molecules) in the flow. This gas flow can be directed to prevent debris produced from reaching specific surfaces within the flow module 576 (for example, the reflective surface 579 of the collector 577, the interior surface 581 of the liner 580, or surfaces of the shroud 585). Thus, this gas flow canreduce damage to the collector 577 otherwise caused by vapor deposition, implantation, and deposition of sputtered target material. When cleaning using the cleaning apparatus 500, the gas flow may be maintained or may be reduced.

[0112] The exhaust opening 582 is configured to remove the released chemical 334 (Fig. 3C) from the interior 575 as well as other gaseous byproducts that can form within the interior 575 during production of the EUV light. As discussed above, the released chemical 334 is formed from the interaction of the plasma particles 333 (produced from the material 132) with the target matter 155 in the form of debris 156 that has deposited on the exposed surface 360 of the component. A removal apparatus 522 such as a pump fluidly communicating with the exhaust opening 582 can therefore remove the released chemical 334 from the interior 575. Once the new chemical 334 is formed, it is released from the exposed surface 360 of the component. And, because the new chemical 334 is in a gaseous state, it can be sucked through the exhaust opening 582 and to the removal apparatus 522, which removes the new chemical 334 from the interior 575.

[0113] The cleaning apparatus 500 can be positioned in the vessel 531, as discussed above, and in turn, the SWP generator 501 can be positioned within the interior 575 at any surface that is in the line of sight of the optical axis OA or is exposed to the plasma 536. The SWP generator 501 of cleaning apparatus 500 can be associated with respective surfaces throughout the interior 575 of the liner 580. For example, the SWP generator 501 can be positioned next to any element that includes a surface that could potentially interact with the target matter 155 and thus potentially become coated with the debris 156 during operation of the EUV light source 570. Thus, the SWP generator 501 can be positioned next to any interior surface (such as the interior surface 581) of the liner 580 or any other surface defined inside the liner 580. It should be noted that the SWP generator 501 can be moved within the interior of the liner 580 and have access to any surface including the interior surface 581 that can be located by using the robotic arm 552 and the arm controller 553 and can extend in any direction along the plane of the page or any distance into or out of the plane of the page.

[0114] While the liner 580 is shown as a single unitary piece, it can be made up of a plurality of pieces. An implementation 680 of a multi -piece conical liner is shown in Fig. 6. The multi-piece liner 680 can include a base sub-liner 680A connecting to a mount 677M that holds the collector 577 and defining the primary focus PF, a middle sub-liner 680B in which the exhaust opening 682 is defined, and a secondary sub-liner 680C that extends toward the intermediate focus IF. Each of the sub-liners 680A, 680B, 680C are conical in shape. The base sub-liner 680A and the middle sub-liner 680B are connected at a first interface 683 and the middle sub-liner 680B and the secondary sub-liner 680C are connected at a second interface 684. The base sub-liner 680A connects to the collector mount 677M at a third interface 685. The base sub-liner 680A defines an interior surface 681 A, the middle sub-liner 680B defines an interior surface 68 IB, and the secondary sub-liner 680C defines an interior surface 681C.

[0115] In some implementations, a cleaning apparatus 100 can be positioned where the collector 577 would have been such that the cleaning apparatus 100 can have access to the interior surfaces 681A, 68 IB, and 681C of the sub-liners 680A, 680B, and 680C. The base sub-liner 680A is a conical shape and includes a circular end 686A that is at the third interface 685 when connected to the collector mount 677M and a circular end 687A that is at the first interface 683 when connected with the middle sub-liner 680B. The cleaning apparatus 100 can be used by placing the base unit 150 where the collector 577 is in Fig. 6, then extending the robotic arm 152 using the arm controller 153 to place the head unit 154 into a desired position with the SWP generator 101 having cleaning distance access to any of the internal surfaces 681A, 68 IB, and 681C of the sub-liners 680A, 680B, and 680C.

[0116] Referring to Fig. 7, a procedure 700 is performed for cleaning the exposed surface of the component of the chamber. The procedure 700 enables the removal of target debris from the exposed surface 160 without separating or removing the component from the chamber. In operation 710, the collector is removed from the vessel of the EUV light source. In operation 720, the cleaning apparatus is installed in the location where the collector was previously located and removed. In operation 730, microwave radiation is generated from an antenna (such as the surface wave plasma generator) that contacts the exposed conducting surface. In operation 740, the microwave radiation is enabled to ionize gas (or material) present at the exposed surface to form a surface wave plasma at the exposed surface . In operations 740 and 750, the generated surface wave plasma is enabled to spread along the exposed surface such that a waveguide is generated between the plasma and the exposed surface. In operation 760, the cleaning apparatus is removed from the chamber, and in operation 770, the collector is reinstalled into the chamber.

[0117] Referring to Fig. 8, a procedure 800 is performed for installing the cleaning apparatus, cleaning the exposed surface of the component of the chamber, and uninstalling the cleaning apparatus. The procedure 800 enables the removal of target debris from the exposed surface without separating or removing the component from the chamber. In operation 820, the cleaning apparatus is installed where the collector was located by placing the base unit into the location of the collector using a collector swap mechanism. In operation 825, the robotic arm is moved using the arm controller to position the SWP generator within cleaning distance from the exposed surface of the component. In operation 830, microwave radiation is generated from an antenna (such as the surface wave plasma generator) that contacts the exposed conducting surface. In operation 840, the microwave radiation is enabled to ionize gas (or material) present at the exposed surface to form a surface wave plasma at the exposed surface. In operation 850, the generated surface wave plasma is enabled to spread along the exposed surface such that a waveguide is generated between the plasma and the exposed surface while the antenna contacts the exposed conducting surface (operation 830). In operation 855, the robotic arm is moved using the arm controller to position the SWP generator for removal from the chamber. In operation 860, the cleaning apparatus is removed from the chamber.

[0118] Figs. 9A-9C illustrate a simplified implementation 900 of the cleaning apparatus 100. The cleaning apparatus 900 includes a base unit 950 having a base (or bottom) plate 955 that is positioned and fixed to the vessel 131 (such as the vessel 431 of Fig. 4A or the liner 580 of Fig. 5), a rotational plate 991 that is configured to rotate relative to the base 955 (the rotation represented by the arrow A991), two or more guide rails 951 to which the base plate 955 is fixed, a robotic arm 952 that is fixed at one portion to the rotational plate 991, and arm controllers 953 configured to control motion of the robotic arm 952. The robotic arm 952 includes the sub-arms 956-1, 956-1. The arm controllers 953 include one or more mechanical devices, such as motors 990 (990-1, 990-2, 990-3, 990-4), telescopic belt drives 980, levers 993, and belts 992, among other devices. The robotic arm 952 is able to rotate along the direction of the arrow A991 due to the rotation of the rotational plate 991 under control of the motor 990-1; tilt along the direction of arrow A993 (by way of the lever 993) under control of the motor 990-4, and translate along the direction A952 under control of motors 990-2, 990-3. The translation along the direction A952 is due to the relative motion between the sub-arm 956-2 (to which the SWP generator 901 is mounted) and the sub-arm 956-1.

[0119] The base plate 955 extends generally in the X,Y plane when fixed to the vessel (such as the vessel 531 of Fig. 5). The bottom plate 955 can be any shape, and is illustrated as a circle or oval. The robotic arm 952 is able to be moved in a rotational pattern in the plane of the base plate 955 about an axis of the base plate 955 by the rotational plate 991. Thus, the robotic arm 952 rotates about the axis of the base plate 955 along the direction of the arrow A991 when the rotational plate 991 rotates.

[0120] The guide rails 951 can be configured to cooperate with the vessel 131 (such as the vessel 431 of Fig. 4A or the liner 580 of Fig. 5) to be guided into position as needed. The conformation of the guide rails 951 and the bottom plate 955 can vary based upon the vessel 131. The guide rails 951 can include mechanical fasteners, grooves, protrusions, etc. to allow for fitment within the vessel 131 . The bottom plate 955 can be sized as needed to fit the vessel 131 and allow additional movement by the robotic arm 152.

[0121] Cam followers 960 can be incorporated to allow the guide rails 951 to properly be fitted into the portion 129 of the vessel 131. The cam followers 960 are provided to allow for the base unit 950 (by way of the guide rails 951) to be moved into the position of the collector 577 using a collector exchange mechanism that can use the cam followers 960 to situate the base unit 950 correctly.

[0122] The telescopic belt drive 980 is provided to telescopically move the robotic arm 952. The telescopic belt drive 980 can lengthen or shorten the robotic arm 952.

[0123] The motors 990, such as linear stepper motors, can be part of the arm controller 153 as disclosed in Fig. 1A. The motors 990, as illustrated in Figs. 9A-9C, are provided to move the robotic arm 152 radially and rotationally along the bottom plate 955.

[0124] The robotic arm 952 can also include a head unit 954 (such as the head unit 154) that can provide a platform for the XRF device 157, cameras 158, sensors, etc. (not shown in Figs. 9A-9C). The head unit 954 can be mounted on the robotic arm 952, where the robotic arm 952 in conjunctionwith the base unit 950 and the arm controller 953 can move and control the head unit 954. The SWP generator 901 is provided on the head unit 954 of the robotic arm 952. The robotic arm 952 is configured to move the SWP generator 901 such that the robotic arm 952 is positioned to allow the surface 160 of the component 165 (Figs. 1A-1C) to be cleaned by the SWP generator 901. Fig. 9C shows the robotic arm 952 in an extended state with the SWP generator 901 translated to a distal location (relative to the base unit 950).

[0125] In other implementations, such as shown in Fig. 10, a cleaning method 1000 can be employed to use the cleaning apparatus 100 is used for cleaning a surface of the component 165 within the vessel 131.

[0126] For example, as illustrated in Fig. 10, an EUV lithography vessel 131, which can be an exposure chamber, with a collector 577 can be provided (1005). Once operating mode is halted, the collector 577 can be removed from the EUV lithography vessel 131 to provide a location for a cleaning apparatus 100 (1010). The cleaning apparatus 100 can be installed into the portion 129 where the collector 577 was previously located (1020). The component 165 can be cleaned in cleaning mode (1030). During cleaning mode, the SWP generator 101 is maneuvered into and through the chamber 130 and to within a cleaning distance De of the surface 160 to be cleaned, and the surface wave plasma 120 is generated. The cleaning apparatus 100 can be removed from the EUV lithography vessel 131 (1040). The EUV lithography vessel 150 can enter operating mode in which EUV lithography occurs (1050) after cleaning is completed.

[0127] In some implementations, the EUV lithography vessel 131 can be configured to receive a substrate (wafer) and thus be configured to receive the EUV light supplied by an EUV light source . In these implementations, the component 165 can be, for example, a reflective optical element configured to, in operating mode, direct EUV light to or from a mask.

[0128] The present disclosure is made with the aid of functional building blocks illustrating the implementation of specified functions and relationships thereof. The boundaries of these functional building blocks have been arbitrarily defined herein to promote clear description. Alternate boundaries can be defined so long as the specified functions are appropriately performed. For example, control module functions can be divided among several systems or performed at least in part by an overall control system.

[0129] The above description includes examples of one or more embodiments. It is, of course, not possible to describe every conceivable combination of components or methodologies for purposes of describing the aforementioned embodiments, but one of ordinary skill in the art after being supplied with this disclosure will recognize that many further combinations and permutations of various embodiments are possible. Accordingly, the described embodiments are intended to embrace all such alterations, modifications, and variations that fall within the spirit and scope of the appended claims. Furthermore, to the extent that the term “includes” is used in either the detailed description or the claims, such term is intended to be inclusive in a manner similar to the term “comprising” as“comprising” is construed when employed as a transitional word in a claim. Furthermore, although elements of the described aspects and / or embodiments may be described or claimed in the singular, the plural is contemplated unless limitation to the singular is explicitly stated or clear from context. Additionally, all or a portion of any aspect and / or embodiment may be utilized with all or a portion of any other aspect and / or embodiment, unless stated otherwise.

[0130] The implementations can be further described using the following clauses.1. An apparatus for cleaning a surface of a component within an extreme ultraviolet (EUV) lithography vessel, the apparatus comprising: a robotic arm comprising an movable portion and arranged relative to the lithography vessel such that movable portion has access to the component surface; and a surface wave plasma (SWP) generator at the movable portion of the robotic arm, the SWP generator configured to generate a surface wave plasma in a region proximate to the movable portion, and, when the movable portion is within a cleaning distance of zero or greater from the component surface, the generated surface wave plasma removes debris from the component surface during cleaning mode.2. The apparatus of clause 1, wherein the EUV lithography vessel is an EUV light source vessel that defines a light source chamber.3. The apparatus of clause 2, wherein the apparatus also comprises a base to which the robotic arm is attached, the base having a geometry that fits within a base opening that receives an EUV light collector.4. The apparatus of clause 2, wherein the component includes a conical liner positioned between the base opening and an exit opening, the liner including an exposed surface that, when installed, faces an optical path between the base opening and the exit opening.5. The apparatus of clause 2, wherein the light source chamber includes an interaction region that aligns with a primary focus of an EUV light collector, and, in operating mode, the EUV light collector is fixed in a base opening and the interaction region receives targets that are converted to plasma that produces EUV light, wherein the debris is deposited on the component surface due to the production of EUV light.6. The apparatus of clause 5, wherein the targets include tin.7. The apparatus of clause 2, wherein the apparatus also comprises a base to which the robotic arm is attached, the base mounted on a side of a conical liner positioned between the base opening and an exit opening, the base configured to introduce the robotic arm and the SWP generator into the light source chamber during cleaning mode and to remove the robotic arm and the SWP generator from the light source chamber prior to EUV operating mode.8. The apparatus of clause 1, wherein the component remains in the EUV lithography vessel while the generated surface wave plasma removes the debris from the component surface during cleaning mode.9. The apparatus of clause 1, wherein the apparatus is configured to be removably introduced into the EUV lithography vessel without needing to remove the component.10. The apparatus of clause 1, wherein the robotic arm is connected to an arm controller configured to control motion of the robotic arm and the SWP generator.11. The apparatus of clause 1, wherein the SWP generator comprises an inner electrical conductor extending along an axial direction and a dielectric insulator outside of the inner electrical conductor and extending along the axial direction.12. The apparatus of clause 11, wherein, in cleaning mode, when the dielectric insulator is within the cleaning distance of the component surface, the generated surface wave plasma removes the debris from the component surface.13. The apparatus of clause 11, wherein, in cleaning mode, the axial direction is adjacent, distant, parallel, or askew to the component surface when the dielectric insulator is within the cleaning distance of the component surface and configured to remove the debris from the component surface.14. The apparatus of clause 1, wherein, in cleaning mode, the SWP generator radiates electromagnetic energy, which transforms a material that is present adjacent the SWP generator from a first state into a plasma state that includes plasma particles, and the plasma particles and the component surface form a waveguide for the propagation of the electromagnetic energy.15. The apparatus of clause 14, wherein, in cleaning mode, part of the guided electromagnetic energy continues to transform material present at another location along the waveguide into the plasma state that includes plasma particles.16. The apparatus of clause 14, wherein, in cleaning mode, at least some of the plasma particles are free radicals and ions of the material, such that the plasma particles come in contact with the debris on the component surface.17. The apparatus of clause 14, wherein the SWP generator radiates electromagnetic energy at a micro wave frequency.18. The apparatus of clause 14, wherein the material present adjacent the SWP generator is in a gas state.19. The apparatus of clause 1, wherein the component surface is an optical surface configured, during operating mode, to operationally interact with electromagnetic radiation.20. The apparatus of clause 1, wherein the component surface is a non -optical surface configured, during operating mode, to not operationally interact with electromagnetic radiation.21. The apparatus of clause 1, wherein the EUV lithography vessel is an EUV lithography exposure vessel that defines an exposure chamber that, in operating mode receives a wafer.22. The apparatus of clause 21, wherein the component is a reflective optical element configured to, in operating mode, direct EUV light to or from a mask.23. An extreme ultraviolet (EUV) lithography apparatus comprising: a lithography vessel defining a chamber;a component of the chamber, the component including a surface exposed to debris during operating mode; and an apparatus for cleaning the exposed surface of the component during a cleaning mode without having to remove the component from the chamber, the apparatus comprising: a robotic arm comprising a movable portion and arranged relative to the lithography vessel such that its movable portion has access to the component surface during the cleaning mode; and a surface wave plasma (SWP) generator at the movable portion of the robotic arm, the SWP generator configured to generate, during the cleaning mode, a surface wave plasma in a region proximate to the movable portion, and, when the movable portion is within a cleaning distance of zero or greater from the component surface, the generated surface wave plasma removes debris from the component surface during the cleaning mode.24. A method of cleaning a component surface in a chamber of an extreme ultraviolet (EUV) lithography vessel, the method comprising: halting an operating mode of the EUV lithography vessel during which the component surface is exposed to debris; and beginning cleaning mode once operating mode is halted, cleaning mode comprising: robotically maneuvering a surface wave plasma (SWP) generator placed at a movable portion of a robotic arm into the chamber of the EUV lithography vessel; robotically maneuvering the SWP generator to within a cleaning distance of zero or greater from the component surface; and generating surface wave plasma at the component surface with the SWP generator to thereby remove debris from the component surface.

[0131] The above-described implementations and other implementations are within the scope of the following claims.

Claims

CLAIMS1. An apparatus for cleaning a surface of a component within a light source vessel, the apparatus comprising: a robotic arm comprising an movable portion and arranged relative to the light source vessel such that movable portion has access to the component surface; and a surface wave plasma (SWP) generator at the movable portion of the robotic arm, the SWP generator configured to generate a surface wave plasma in a region proximate to the movable portion, and, when the movable portion is within a cleaning distance of zero or greater from the component surface, the generated surface wave plasma removes debris from the component surface during a cleaning mode.

2. The apparatus of claim 1, wherein the light source vessel is an extreme ultraviolet (EUV) light source vessel that defines a light source chamber.

3. The apparatus of claim 2, wherein the apparatus also comprises a base to which the robotic arm is attached, the base having a geometry that fits within a base opening that receives an EUV light collector.

4. The apparatus of claim 2, wherein the component includes a conical liner positioned between the base opening and an exit opening, the liner including an exposed surface that, when installed, faces an optical path between the base opening and the exit opening.

5. The apparatus of claim 2, wherein the light source chamber includes an interaction region that aligns with a primary focus of an EUV light collector, and, in an operating mode, the EUV light collector is fixed in a base opening and the interaction region receives targets that are converted to plasma that produces EUV light, wherein the debris is deposited on the component surface due to the production of EUV light.

6. The apparatus of claim 2, wherein the apparatus also comprises a base to which the robotic arm is attached, the base mounted on a side of a conical liner positioned between the base opening and an exit opening, the base configured to introduce the robotic arm and the SWP generator into the light source chamber during the cleaning mode and to remove the robotic arm and the SWP generator from the light source chamber prior to an operating mode.

7. The apparatus of claim 1, wherein the component remains in the light source vessel while the generated surface wave plasma removes the debris from the component surface during the cleaning mode.

8. The apparatus of claim 1, wherein the apparatus is configured to be removably introduced into the light source vessel without needing to remove the component.

9. The apparatus of claim 1, wherein the SWP generator comprises an inner electrical conductor extending along an axial direction and a dielectric insulator outside of the inner electrical conductor and extending along the axial direction.

10. The apparatus of claim 9, wherein, in the cleaning mode, when the dielectric insulator is within the cleaning distance of the component surface, the generated surface wave plasma removes the debris from the component surface.

11. The apparatus of claim 9, wherein, in the cleaning mode, the axial direction is adjacent, distant, parallel, or askew to the component surface when the dielectric insulator is within the cleaning distance of the component surface and configured to remove the debris from the component surface.

12. The apparatus of claim 1, wherein, in the cleaning mode, the SWP generator radiates electromagnetic energy, which transforms a material that is present adjacent the SWP generator from a first state into a plasma state that includes plasma particles, and the plasma particles and the component surface form a waveguide for the propagation of the electromagnetic energy.

13. The apparatus of claim 12, wherein, in the cleaning mode, part of the guided electromagnetic energy continues to transform material present at another location along the waveguide into the plasma state that includes plasma particles.

14. The apparatus of claim 12, wherein, in the cleaning mode, at least some of the plasma particles are free radicals and ions of the material, such that the plasma particles come in contact with the debris on the component surface.

15. The apparatus of claim 12, wherein the material present adjacent the SWP generator is in a gas state.

16. The apparatus of claim 1, wherein the component surface is an optical surface configured, during an operating mode, to operationally interact with electromagnetic radiation.

17. The apparatus of claim 1, wherein the component surface is a non -optical surface configured, during an operating mode, to not operationally interact with electromagnetic radiation.

18. The apparatus of claim 1, wherein the light source vessel is an exposure vessel that defines an exposure chamber that, in an operating mode receives a wafer.

19. A extreme ultraviolet (EUV) light source comprising: a vessel defining a chamber; a component of the chamber, the component including a surface exposed to debris during an operating mode; and an apparatus for cleaning the exposed surface of the component during a cleaning mode without having to remove the component from the chamber, the apparatus comprising: a robotic arm comprising a movable portion and arranged relative to the vessel such that its movable portion has access to the component surface during the cleaning mode; and a surface wave plasma (SWP) generator at the movable portion of the robotic arm, the SWP generator configured to generate, during the cleaning mode, a surface wave plasma in a region proximate to the movable portion, and, when the movable portion is within a cleaning distance of zero or greater from the component surface, the generated surface wave plasma removes debris from the component surface during the cleaning mode.

20. A method of cleaning a component surface in a chamber of an extreme ultraviolet (EUV) vessel, the method comprising: halting an operating mode of the EUV vessel during which the component surface is exposed to debris; and beginning a cleaning mode once the operating mode is halted, the cleaning mode comprising: robotically maneuvering a surface wave plasma (SWP) generator placed at a movable portion of a robotic arm into the chamber of the EUV vessel; robotically maneuvering the SWP generator to within a cleaning distance of zero or greater from the component surface; and generating surface wave plasma with a microwave frequency at the component surface with the SWP generator to thereby remove debris from the component surface.

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