Protective system for an extreme ultraviolet light source

Abstract

A target delivery system for an extreme ultraviolet (EUV) source includes a conduit including an exterior, an interior conduit region, and an end defining an orifice. The interior conduit region is configured to receive a target material that emits EUV light when in a plasma state, and the orifice is configured to provide the target material toward an interior of a vacuum chamber. The target delivery system also includes a protection system configured to flow a protective gas away from the end defining the orifice and toward the interior of the vacuum chamber. The flowing protective gas is configured to direct one or more contaminant species away from the end defining the orifice.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to U.S. Application No. 62 / 845,007, filed May 8, 2019, entitled “Protection System for Extremely Violet Light Source,” which is incorporated herein by reference in its entirety. Technical Field

[0003] This disclosure relates to a protection system for extreme ultraviolet (EUV) light sources. Background Technology

[0004] Extreme ultraviolet (“EUV”) light (e.g., electromagnetic radiation with wavelengths below 100 nanometers (nm) (sometimes also called soft X-rays), and including light with wavelengths such as below 20 nm, between 5 and 20 nm, or between 13 and 14 nm) can be used in photolithography processes to create tiny features in a substrate (e.g., a silicon wafer) by initiating polymerization in a resist layer.

[0005] Methods for generating EUV light include, but are not limited to, converting materials containing elements such as xenon, lithium, or tin that, when in a plasma state, exhibit emission spectra in the EUV range. In one such method, commonly referred to as laser-generated plasma (“LPP”), the desired plasma is generated by irradiating a target material, such as a droplet, plate, strip, stream, or cluster, with an amplified beam, which may be referred to as a driving laser. For this process, the plasma is typically generated in a sealed container (e.g., a vacuum chamber) and monitored using various types of measurement equipment. Summary of the Invention

[0006] In one aspect, a target delivery system for a far-ultraviolet (EUV) light source includes: a conduit comprising an outer conduit region, an inner conduit region, and an end defining an orifice. The inner conduit region is configured to receive target material that emits EUV light when in a plasma state, and the orifice is configured to deliver the target material into the interior of a vacuum chamber. The target delivery system also includes a protection system configured to direct a protective gas away from the end defining the orifice and toward the interior of the vacuum chamber. The flowing protective gas is configured to guide one or more contaminants away from the end defining the orifice.

[0007] The implementation may include one or more of the following features. The protective gas may include an inert gas or a reactive gas.

[0008] Protective gases may include molecular hydrogen (H2).

[0009] The protection system can be configured to allow a protective gas to flow along the exterior of the conduit. The protection system may include a body comprising sidewalls surrounding at least a portion of the exterior of the conduit, the body defining an open end region aligned with an orifice of the conduit. The protective gas can flow in an open space between the exterior of the conduit and the inner wall of the sidewalls, and the protective gas can flow through the open end region to exit the body. The sidewalls may include at least one port in fluid communication with the open space, the at least one port being configured to fluidly couple to a gas supply device containing the protective gas.

[0010] The protection system includes at least one gas source.

[0011] The target delivery system may further include a temperature control block that at least partially surrounds the exterior of the conduit, and a protection system may include a body that surrounds at least a portion of the temperature control block, defining an open end region aligned with the orifice of the conduit. A protective gas may flow in the open space between the temperature control block and the inner wall of the body, and the protective gas may exit the body through the open end region.

[0012] One or more contaminants may include mobile substances, and the flowing fluid may be configured to reduce the interaction between one or more mobile contaminants and the end of the conduit by changing the direction of movement of one or more mobile contaminants away from the end of the conduit.

[0013] One or more contaminants may include mobile substances, and the flowing fluid may be configured to prevent interaction between one or more mobile contaminants and the end of the conduit by changing the direction of movement of one or more mobile contaminants away from the end of the conduit.

[0014] One or more pollutants may include one or more of the following: gas, liquid, vapor, and particulate matter.

[0015] One or more pollutants may include silicon (Si) or silicon dioxide (SiO2).

[0016] One or more pollutants may include oxygen, water, or carbon dioxide (CO2).

[0017] Conduits may include capillaries.

[0018] The protection system may include a diffuser device comprising a plurality of openings, each of which can be configured to guide protective gas away from an end of a defined orifice. The plurality of openings may surround the exterior of the conduit and may be uniformly distributed relative to the exterior of the conduit.

[0019] In another aspect, a method for protecting the orifice of a target material delivery system includes: allowing target material to pass through the orifice to provide a target flow into the interior of a vacuum chamber, each target in the flow including target material that emits EUV light when in a plasma state; and allowing a protective gas to flow through the target material delivery system and away from the orifice into the interior of the vacuum chamber, the protective gas guiding one or more contaminants away from the orifice.

[0020] The implementation may include one or more of the following features. In some implementations, the flowing protective gas does not alter the trajectory of the target flow. The flowing protective gas may have a motion component along the direction of travel of the target flow.

[0021] Allowing the protective gas to flow can include allowing the protective gas to flow in an open space between a conduit defining an orifice and a body surrounding the conduit. The protective gas can flow into the open space at a port in the body and can flow out of the space through an open end region defined by the body and aligned with the orifice.

[0022] The protective gas can have a uniform volumetric flow rate at the aperture between the orifice and the interior of the vacuum chamber.

[0023] The method may also include determining the state of the extreme ultraviolet light source, including the target material delivery system; and determining, based on the determined state, which of a variety of protective gases to use as the protective gas.

[0024] Implementations of any of the above-described technologies may include an EUV light source, a target supply system, a method, process, apparatus, or device. Details of one or more implementations are set forth in the accompanying drawings and the following description. Other features will become clear from the description, the drawings, and the claims. Attached Figure Description

[0025] Figure 1 This is a block diagram of an example EUV light source.

[0026] Figure 2A This is a side cross-sectional view of an example supply system.

[0027] Figure 2B yes Figure 2A The supply system along Figure 2A The bottom view of line 2A-2A'.

[0028] Figure 2C This is a side cross-sectional view of another example of a supply system.

[0029] Figure 2D yes Figure 2C The supply system along Figure 2C The bottom view of line 2C-2C'.

[0030] Figure 3A This is a side cross-sectional view of another example of a supply system.

[0031] Figure 3B yes Figure 3A A top view of the supply system.

[0032] Figure 4A This is a side cross-sectional view of another example of a supply system.

[0033] Figure 4B yes Figure 5A A top view of the supply system.

[0034] Figure 5A and Figure 5B This is a flowchart of an example process related to the flow of protective gas.

[0035] Figure 6 and Figure 7 This is a block diagram of an example photolithography equipment.

[0036] Figure 8 This is a block diagram of an example EUV light source. Detailed Implementation

[0037] refer to Figure 1 A block diagram of an EUV light source 100 including a supply system 110 is shown. The supply system 110 includes a protection system 130, which guides a protective gas 131 (in... Figure 1 , Figure 3A and Figure 4A (Shown in dashed form) to protect the supply system 110 from the supply system 110. Protective gas 131 carries pollutant 150 (in...) Figure 1 (shown as shaded circles) away from supply system 110 and / or to prevent contaminants 150 from reaching supply system 110.

[0038] Supply system 110 emits target stream 121, such that target 121p is delivered to plasma formation position 123 in vacuum chamber 109. Target 121p includes target material, which is any material having an emission spectrum in the extreme ultraviolet (EUV) range when in a plasma state. Target material can be, for example, tin, lithium, or xenon. Other materials can be used as target materials. For example, elemental tin can be used as pure tin (Sn); tin compounds, such as SnBr4, SnBr2, SnH4; tin alloys, such as tin-gallium alloys, tin-indium alloys, tin-indium-gallium alloys, or any combination of these alloys.

[0039] Plasma formation location 123 receives light beam 106. Light beam 106 is generated by light source 105 and transported to vacuum chamber 109 via optical path 107. The interaction between light beam 106 and target material in target 121p generates plasma 196 emitting EUV light 197. Optical element 198 guides EUV light 197 toward lithography tool 199.

[0040] The supply system 110 includes a conduit 112. The conduit 112 is a three-dimensional object, such as a tube or cylinder, defined by a sidewall 114. The sidewall 114 extends from a first end 115 to a second end 116. The second end 116 includes an orifice 117 that passes through the sidewall 114 into the interior of the conduit 112 and is fluidly coupled to a reservoir 140. The reservoir 140 holds a target mixture 141, which includes a target material and may also include impurities. In operational use, the target mixture 141 flows within the conduit 112 and is emitted from the orifice 117 as a stream 121.

[0041] exist Figure 1 In this example, the supply system 110 also includes an actuator 135 mechanically coupled to a sidewall 114. The actuator 135 may be, for example, a piezoelectric ceramic material, such as lead zirconate titanate (PZT), which changes shape in response to the application of voltage. The sidewall 114 is deformed by the actuator 135. Deformation of the sidewall 114 regulates the pressure of the target mixture in the conduit 112 and causes the target material flowing into the target stream 121 through the orifice to break up. The size and spacing of the targets in the stream 121 can be controlled by controlling the frequency and / or amplitude of the deformation applied by the actuator 135. The stream 121 includes multiple different spherical targets with a diameter, for example, 30 micrometers (µm). The supply system 110 may also deliver the target material to the vacuum chamber 109 in another manner. For example, the supply system 110 may generate a jet of target material that does not break up into individual targets.

[0042] The supply system 110 also includes a protection system 130. The protection system 130 includes a gas guiding system 132 that guides the protective gas 131 away from the second end 116. The gas guiding system 132 includes a gas management system 167, which includes means, components, and / or systems configured to guide the protective gas 131. For example, the gas guiding system 132 may include a pump, flow control devices (such as valves and / or fluid switches), openings through which the protective gas 131 flows, and / or nozzles.

[0043] The gas guiding system 132 is fluidly coupled to the gas supply device 133 via a fluid connector 134. The gas supply device 133 includes a chamber 137 that contains a gas used as a protective gas 131. For example, the chamber 137 of the gas supply device 133 may contain an inert gas or a reactive gas. An inert gas is a gas that does not react with anything in the vacuum chamber 109. A reactive gas is a gas that can react with one or more items within the vacuum chamber 109. The protective gas 131 may be, for example, molecular hydrogen (H2) or argon (Ar). The protective gas 131 may include non-gaseous substances. For example, the protective gas 131 may include solid nanoclusters carried by the protective gas 131.

[0044] In some implementations, chamber 137 contains more than one different gas. For example, chamber 137 may include multiple chambers that are not fluidly coupled to each other, but each chamber is configured to be fluidly coupled to fluid connector 134. In these implementations, one chamber may include, for example, molecular hydrogen (H2), and another chamber may include argon (Ar). In implementations including more than one chamber 137, gas management system 167 includes a fluid switching mechanism that allows selection of one of the multiple chambers 137.

[0045] exist Figure 1 In the example, flow 121 generally travels in the -X direction, and protective gas 131 also flows along sidewall 114 and into vacuum chamber 109 in the -X direction. Second end 116 extends substantially in the YZ plane. Therefore, protective gas 131 flows away from second end 116 and orifice 117. By guiding protective gas 131 away from second end 116, protection system 130 protects supply system 110 from contaminants 150. In various implementations, protective gas 131 is parallel or substantially parallel to the direction of motion of the target in flow 121.

[0046] The contaminant 150 is any substance capable of blocking orifice 117 and / or adhering to the second end 116 in a manner that blocks orifice 117. For example, the contaminant 150 may be able to form a layer on the second end 116 that completely or partially blocks orifice 117. The contaminant 150 moves within the vacuum chamber 109. For example, in the absence of protective gas 131, the contaminant 150 may move toward the second end 116 and / or orifice 117. In response to interaction with protective gas 131, the contaminant 150 moves away from the second end 116 and orifice 117.

[0047] Pollutant 150 may include solid, liquid, and / or gaseous substances. Pollutant 150 may include more than one type of pollutant and / or more than one substance. For example, pollutant 150 may include particles of silicon dioxide, siloxanes, silicon dioxide (SiO2), tin oxide (SnO2), gases (such as oxygen), and / or vapors (such as tin vapor). Pollutant 150 may include, for example, vapors of silicon (Si), silicon dioxide (SiO2), and / or tin oxide (SnO2) capable of being vapor-deposited onto the second end 216. Pollutant 150 may originate from components within vacuum chamber 109, and / or from the interaction of articles within vacuum chamber 109 with oxygen, water, and / or carbon dioxide (CO2) when vacuum chamber 109 is depressurized.

[0048] By guiding the contaminant 150 away from the second end 116, the protective gas 131 prevents or reduces the likelihood of a layer of contaminant 150 forming on the second end 116. A layer of contaminant 150 on the second end 116 may interfere with the formation of the flow 121. For example, such a layer can completely or partially block the orifice 117, thereby blocking the flow 121 and / or altering the nature of the flow 121. Because the flow 121 includes the target for generating EUV light 197, unexpected and / or undesirable alterations in the flow 121 may lead to a reduction in the generation of EUV light 197. Therefore, by guiding the contaminant 150 away from the end 116 and the orifice 117, the protective system 130 improves the overall performance of the supply system 110 and the EUV light source 100. In addition to improving the overall performance of the EUV light source 100 during operation, the protective system 130 also reduces the downtime of the EUV light source 100. For example, to remove a layer of contaminant 150 from the second end 116, the supply system 110 is removed from the EUV light source 100. Therefore, by preventing or reducing the accumulation of pollutants 150 on the second end 116, the protection system 130 also reduces the amount of maintenance performed on the supply system 110 and reduces the downtime of the EUV light source 100.

[0049] The EUV light source 100 also includes a control system 160 for controlling the operation of the protection system 130. The control system 160 may be coupled to the gas supply device 133, the gas management system 167, and / or the gas guiding system 132. For example, the control system 160 may control the flow rate of the protective gas 131 by controlling valves and / or pumps within the gas guiding system 132 or the gas supply device 133. In another example, in an implementation where the gas supply device 133 includes multiple chambers 137, the control system 160 may be used to control switches in the gas management system 167. This allows the control system 160 to switch between chambers such that the protective gas 131 is formed from the gas in one of the chambers at a specific time. The control system 160 may also be coupled to other systems and components of the EUV light source 100, such as the actuator 135 and / or the light source 105.

[0050] The control system 160 includes an electronic processing module 161, an electronic storage device 162, and an I / O interface 163. The electronic processing module 161 includes one or more processors suitable for executing computer programs, such as general-purpose or special-purpose microprocessors and any type of digital computer. Typically, the electronic processor receives instructions and data from read-only memory, random access memory (RAM), or both. The electronic processing module 161 can be any suitable type of electronic processor.

[0051] Electronic storage device 162 may be a volatile memory, such as RAM, or a non-volatile memory. In some implementations, electronic storage device 162 includes both non-volatile and volatile portions or components. Electronic storage device 162 may store data and information used in the operation of control system 160. For example, electronic storage device 162 may store information about the operation of supply system 110 and / or protection system 130. For example, in some implementations, electronic storage device 162 stores the flow rate of protective gas 131 that should flow from gas guiding system 132 during typical operation of EUV light source 100.

[0052] The electronic storage device 162 also stores instructions, such as one or more computer programs, which, when executed, cause the electronic processing module 161 to communicate with components in the supply system 110 and / or protection system 130. For example, the electronic storage device 162 may store instructions that cause the electronic processing module 161 to provide a modulated signal sufficient to cause the actuator 135 to vibrate the conduit.

[0053] I / O interface 163 is any type of interface that allows control system 160 to receive or send information or data. For example, I / O interface 163 may be a keyboard, mouse, or other computer peripherals that enable an operator to operate and / or program control system 160. I / O interface 163 may include devices that generate perceptible alarms, such as lights or speakers. Furthermore, I / O interface 163 may include communication interfaces, such as universal serial ports (USB), network connectors, or any other interface that allows communication with control system 160.

[0054] Figure 2A This is a side cross-sectional view of the supply system 210 in the XZ plane. The supply system 210 includes a conduit 212 and a gas guiding system 232. Figure 2B This is a bottom view of the conduit 212 and the gas guiding system 232 in the YZ plane, as shown from... Figure 2A As seen on line 2A-2A'. Figure 2B The X direction is the direction of entry into the page. The conduit 212 can be used with the EUV light source 100 (…). Figure 1 The conduit includes a sidewall 214 extending from a first end 215 along the X direction to a second end 216. The sidewall 214 forms a conduit 212, which is a three-dimensional object that is generally cylindrical and has a generally tapered nozzle 250 at the end 216. The conduit 212 may be, for example, a capillary.

[0055] The sidewall 214 includes an inner surface 253 and an outer wall 254. The inner surface 253 defines an internal region 258 in fluid communication with the nozzle 250. Figure 2A and Figure 2B The nozzle 250 narrows along the -X direction to define the orifice 217. Figure 2A and Figure 2B In the example, nozzle 250 is generally conical and orifice 217 is at the apex of the cone. The internal region 258 is fluid-coupled to contain the target mixture (such as...). Figure 1 The storage container (such as the target mixture 141) Figure 1 The reservoir 140), and the target mixture flows in the inner region 258 of the conduit 212 and flows through the orifice 217 in the -X direction.

[0056] The gas guiding system 232 is a three-dimensional volume surrounding a space 238. This space 238 is fluidly coupled to a gas supply device 133. The gas guiding system 232 includes a plurality of openings 236 passing through a bottom 239 of the gas guiding system 232. For simplicity, in Figure 2A and Figure 2BOnly one of the openings 236 is marked. Protective gas 131 flows into space 238 from gas supply device 133 and exits through opening 236 in the -X direction. The flow rate and direction of the protective gas 131 leaving each opening 236 are substantially the same.

[0057] exist Figure 2B In the example, opening 236 is arranged in a linear grid within the bottom 239. However, other implementations are possible. For example, opening 236 could be arranged in a random pattern. Furthermore, opening 236 could have any shape. Figure 2B In the example, each opening 236 is circular in the YZ plane. In other implementations, the opening 236 can be elliptical, or the openings can form concentric circles centered on the aperture 217.

[0058] Furthermore, the gas guiding system 232 can have any shape. Figure 2B In the example, the gas guiding system 232 is a cylinder with a circular cross-section in the YZ plane. In other implementations, the gas guiding system 232 may have, for example, a square or rectangular cross-section in the YZ plane.

[0059] exist Figure 2A and Figure 2B In the example, the gas guiding system 232 is a single element comprising a plurality of openings 236, each opening 236 guiding the protective gas 131 in a direction away from the nozzle 250. However, other implementations are also possible. For example, the gas guiding system 232 may be an aggregation of discrete gas collection systems, each discrete gas collection system being individually fluidly coupled to the gas supply device 133 or a separate gas supply device. In these implementations, each gas guiding system is individually controllable (e.g., utilizing...). Figure 1 The control system 160 provides the flow of protective gas 131.

[0060] In addition, the supply system 210 may include in Figure 2A and Figure 2B Additional components not shown. For example, supply system 210 may include actuators (such as...) outside conduit 212. Figure 1 Actuator 135).

[0061] Figure 2C and Figure 2D A supply system 210C, identical to supply system 210, is shown, except that supply system 210C includes an actuator 235 mounted to and surrounding a portion of outer wall 254. Actuator 235 in... Figure 2C and Figure 2D The image is shown in crosshairs. Figure 2C This is a cross-sectional view of the supply system 210C in the XZ plane. Figure 2DFrom Figure 2C The bottom view of supply system 210C is seen from the perspective view of line 2C-2C'. Supply system 210C is Figure 1 Another example of the implementation of the supply system 110. Actuator 235 is actuator 135 ( Figure 1 An example of the implementation of ).

[0062] Actuator 235 is a three-dimensional cylinder comprising an inner surface 259 and an outer surface 257. The inner surface 259 of actuator 235 is mechanically coupled to a portion of the outer wall 254 of conduit 212 via, for example, an adhesive material. Actuator 235 surrounds a portion of the outer wall 254. Figure 2D As shown, actuator 235 has a circular cross-section in the YZ plane.

[0063] Actuator 235 can be made of a solid material (such as PZT) to which the protective gas 131 is impermeable. The adhesive coupling actuator 235 can be, for example, epoxy resin, which is also generally impermeable to the protective gas 131. Therefore, under normal operation, when actuator 235 is properly coupled to outer wall 254, protective gas 131 flows around actuator 235. In this configuration, actuator 235 is located between gas guiding system 232 and orifice 217, such as... Figure 2C and Figure 2D In the illustrated implementation, the protective gas 131 flows along the outer wall 254, except at the portion where the actuator 235 is attached to the conduit 212. At the portion where the actuator 235 is attached to the conduit 212, the protective gas 131 still flows along the conduit 212, but the protective gas 131 flows around the outer surface 357 of the actuator 235. In other words, the protective gas 131 flowing along the outside of the conduit 212 includes situations where the protective gas 131 flows around an article (such as the actuator 235) attached to the outer wall 245 of the conduit 212, and this article cannot be permeated by the protective gas 131.

[0064] refer to Figure 3A and Figure 3B The diagram illustrates supply system 310. Supply system 310 is another example of supply system 110. Supply system 310 can be used for... Figure 1 In the EUV light source 100. For example, the supply system 310 can be installed in the vacuum chamber 109 and used to generate the target flow 121. Figure 3A This is a cross-sectional view of the supply system 310 in the XZ plane. Figure 3B This is a view of end 379 of the supply system 310 in the YZ plane. Figure 3B In the text, the X direction is the direction from which you enter the page.

[0065] The supply system 310 includes conduit 212 (as mentioned above) Figure 2A and Figure 2B (Discussion) and housing 370. Housing 370 is a three-dimensional body surrounding conduit 212. Housing 370 includes sidewalls 371. Sidewalls 371 define a fluid port 372 coupled to gas supply device 133. Fluid port 372 can be connected to fluid connectors (such as...) Figure 1 The fluid connector 134, or fluid port 372, can be directly coupled to the gas supply device 133. The sidewall 371 also defines an open area 378 at the end 379.

[0066] Fluid port 372 is open to the interior 373 of housing 370. Conduit 212 is located within interior 373. Conduit 212 and housing 370 are positioned relative to each other such that orifice 217 of conduit 212 is aligned with open region 378 along the X direction. The alignment of orifice 217 and open region 378 allows target material ejected from orifice 217 to exit housing 370 along the -X direction.

[0067] Sidewall 371 includes inner wall 375, which is separated from outer wall 254 of conduit 212 to form open space 376. Open space 376 is a portion of interior 373 (within housing 370) located between outer wall 254 and inner wall 375 of conduit 212. Open space 376 is fluidly coupled to fluid port 372. Protective gas 131 in supply device 133 is maintained at a pressure higher than that in vacuum chamber 109, so protective gas 131 flows from gas supply device 133 into fluid port 372 and into open space 376. Pressure in vacuum chamber 109 is lower than that in interior 373. Protective gas 131 generally flows along outer wall 254 of conduit 212 in the -X direction and exits housing 370 through open region 378. Protective gas 131 and target material both flow through open region 378 in substantially the same direction. Figure 3A and Figure 3B In the example, the target material and protective gas 131 move generally in the -X direction through the open region 378.

[0068] The protective gas 131 can have a uniform flow rate at all points in the YZ plane within the open region 378, and substantially does not interfere with the trajectory of the target material passing through the open region 378. The flow of the protective gas 131 in the XY plane within the open region 378 is referred to as the gas flow field. Although the gas flow field may affect the trajectory of individual targets launched from the orifice 317, the characteristics of the gas flow field (e.g., flow rate and direction) ensure that the trajectory of the individual targets remains substantially unchanged. For example, the gas flow field will not cause the target trajectory to deviate too much, such that the target in the flow 121 will not be transported to the plasma formation location 123 ( Figure 1Furthermore, the mass and density of the target launched from orifice 317 are much higher than those of the protective gas 131. The ratio of the target's mass and / or density to that of the protective gas 131 also minimizes the influence of the protective gas 131 on the target's trajectory.

[0069] The flow rate of protective gas 131 is sufficient to remove pollutant 150 ( Figure 1 The protective gas 131 moves away from the open area 378 and / or is sufficient to prevent the contaminant 150 from moving through the open area 378 and into the open space 376. The flow rate of the protective gas 131 is higher than the diffusion rate of the contaminant 150. Diffusion is the net movement of material (e.g., molecules or atoms in the contaminant 150) from a region of higher concentration (or high chemical potential) to a region of lower concentration (or low chemical potential). Diffusion is driven by the gradient of the chemical potential of the diffusing substance. The protective gas 131 can be considered to mitigate the movement of the contaminant 150 into the orifice 317 through the Peclet effect, which is quantified by the Peclet number (Pe). The Peclet number is the ratio of the advection transport rate to the diffusion transport rate. The advection transport rate is the transport rate of the protective gas 131. The diffusion transport rate is the diffusion rate of the contaminant 150. As the Peclet number increases, the protective gas 131 is more likely to dominate the interaction between itself and the contaminant 150, and the protective gas 131 is more likely to push the contaminant 150 away from the release area 378. The Peclet number can be increased by increasing the flow rate of the protective gas 131 and / or increasing the characteristic length (e.g., the length of the protective gas 131 flowing in the X direction in the supply system 310). Therefore, the Peclet number and the mitigation of the contaminant 150 are controllable through the design of the housing 370 and / or the control of the flow rate of the protective gas 131.

[0070] In some implementations, the flow rate of the protective gas 131 can be between 1 and 50 standard liters per minute (slm). The flow rate of the protective gas 131 at the open area 378 depends on the extent of the open space 376 in the X direction, the flow rate of the protective gas 131 from the gas supply device 133 into the fluid port 372, the physical properties of the inner wall 375, and the size of the open area 378 in the YZ plane.

[0071] Figure 3A and Figure 3B The example includes a single fluid port 372. However, in other implementations, more fluid ports may be used. For example, multiple fluid ports 372 may be included. The multiple fluid ports 372 may be circumferentially spaced and equidistant from each other in the YZ plane. Furthermore, in some implementations, the supply system 310 includes an actuator, such as actuator 237, attached to and surrounding a portion of the outer wall 254. Figure 2C and Figure 2D When the actuator is located between fluid port 372 and orifice 217, protective gas 131 flows along the outer wall 254 and / or outer surface of the actuator. When the actuator is attached to the outer wall 254, protective gas 131 does not flow between the actuator and the outer wall 254.

[0072] Figure 4A and Figure 4B Supply system 410 is shown. Supply system 410 is another example of an implementation of supply system 110. Supply system 410 can be used for Figure 1 In the EUV light source 100. For example, the supply system 410 can be installed in the vacuum chamber 109 and used to generate the target flow 121. Figure 4A This is a cross-sectional view of the supply system 410 in the XZ plane. Figure 4B This is a view of end 479 of the supply system 410 in the YZ plane. Figure 4B In the diagram, the X direction is the direction of entry into the page. Supply system 410 is similar to supply system 310 ( Figure 3A and Figure 3B The difference is that the supply system 410 includes a temperature control block 480, which controls the temperature of the conduit 212 and / or the nozzle 250.

[0073] The supply system 410 includes a housing 470. The housing 470 includes a sidewall 471 defining an interior 473. The conduit 212 ( Figure 2A and Figure 2B Inside 473. The conduit 212 and the housing 470 are positioned relative to each other such that the orifice 217 is aligned with the open area 478 at the end 479 of the housing. The stream 121 emitted from the orifice 217 exits the housing 470 in the -X direction.

[0074] The supply system 410 includes a temperature control block 480. The temperature control block 480 is located within an interior 473. The temperature control block 480 surrounds at least a portion of the outer wall 254 of the conduit 212. Figure 4A and Figure 4B In the example, the temperature control block 480 is a cylinder with a longitudinal axis along the X direction, which is concentric with the longitudinal axis of the conduit 212 along the X direction.

[0075] Temperature control block 480 is made of a material that can be heated or cooled. Temperature control block 480 can be made of any thermally conductive material. Temperature control block 480 is thermally coupled to a controllable heater and / or cooler, making the temperature of control block 480 controllable. Temperature control block 480 can be a solid block, for example, having corrosion resistance to the target material. In implementations where the target material includes tin, temperature control block 480 can be, for example, molybdenum (Mo).

[0076] The temperature control block 480 is positioned close enough to the outer wall 254 to influence the temperature of the outer wall 254 (and therefore the conduit 212), but the temperature control block 480 does not contact the outer wall 254. If the temperature control block 480 is hotter than the conduit 212, the temperature control block 480 heats the conduit 212. Heating the conduit 212 can, for example, promote more efficient flow of the target material within the conduit 212. When the temperature control block 480 is colder than the conduit 212, the temperature control block 480 lowers the temperature of the conduit 212.

[0077] The temperature control block 480 does not have direct physical contact with the outer wall 254, and there is an open space 481 between the temperature control block 480 and the outer wall 254. Fluid (such as protective gas 131) can flow within the open space 481 between the temperature control block 480 and the wall 254. The temperature control block 480 can be mounted to the inner wall 475 of the housing 470 or the reservoir 140. Therefore, the temperature control block 480 does not necessarily need to contact the inner wall 475, and fluid (such as protective gas 131) can flow between the temperature control block 480 and the inner wall 475. Figure 4A and Figure 4B In this implementation, open space 482 is located between temperature control block 480 and inner wall 475, and open space 481 is located between temperature control block 480 and outer wall 254 of conduit 212. Protective gas 131 flows in open spaces 481 and 482.

[0078] Sidewall 471 defines fluid port 472, which is fluidly coupled to gas supply device 133 and interior 473. Protective gas 131 flows from gas supply device 133 into interior 473. The pressure in vacuum chamber 109 is lower than the pressure in interior 473, and protective gas 131 is drawn in through open spaces 481 and 482.

[0079] Protective gas 131 flows generally in the -X direction through open region 478 and into vacuum chamber 109. Protective gas 131 and flow 121 flow in the open region 478 in generally the same direction (-X direction). Therefore, protective gas 131 flows through open region 478 and into vacuum chamber 109 in a direction away from orifice 217 and away from end 479. The flow direction of protective gas 131 prevents or avoids contaminant 150 from passing through open region 478 into housing 470 and reduces the possibility of orifice 217 being blocked by contaminant 150.

[0080] The protective gas 131 has a uniform flow rate at all points in the YZ plane within the open region 478, and therefore does not interfere with the trajectory of the target material passing through the open region 478. The flow rate of the protective gas 131 is sufficient to move contaminant 150 away from the open region 478 and / or sufficient to prevent contaminant 150 from moving through the open region 478 into the interior 473. For example, the flow rate of the protective gas 131 can be from 1 to 50 standard liters (slm) per minute. The flow rate of the protective gas 131 in the open region 478 depends on the extent of the open spaces 481 and 482 in the X direction, the size and placement of the temperature control block 480, the flow rate of the protective gas 131 from the gas supply device 133 into the fluid port 472, the pressure difference between the interior 473 and the vacuum chamber 109, the physical properties of the inner wall 475, and the size of the open region 478 in the YZ plane.

[0081] Other implementations are also possible. For example, the temperature control block 480 can be mounted to the inner wall 475 so that fluid does not flow between the inner wall 475 and the temperature control block 480. In these implementations, the protective gas 131 flows only in the open space 481.

[0082] In addition, the supply system 410 may include a gas guiding system, such as Figure 2A and Figure 2B The gas guiding system 232 can be mounted on the temperature control block 480 and mounted in the x-direction relative to the open region 378. For example, the gas guiding system 232 can be mounted at the end of the temperature control block 480 closest to the open region 378. In an implementation including the gas guiding system 232, the diameter of the gas guiding system 232 in the YZ plane is slightly larger than the diameter of the open region 378 in the YZ plane.

[0083] Furthermore, in some implementations, the supply system 410 includes a three-dimensional actuator, such as actuator 237, attached to and surrounding a portion of the outer wall 254. Figure 2C and Figure 2D When the actuator is located between fluid port 472 and orifice 217, protective gas 131 flows along the outer wall 254 and / or outer surface of the actuator. Temperature control block 480 is not connected to the actuator. Therefore, in these implementations, all or part of space 481 may be located between temperature control block 480 and the actuator. When the actuator is attached to outer wall 254, protective gas 131 does not flow between the actuator and outer wall 254.

[0084] Referring to Figure 5, a flowchart of process 500 is shown. Process 500 is an example of a process for protecting an orifice of a supply system (e.g., orifice 217 of conduit 212 (Figure 2)). Figure 5 discusses orifice 217. However, process 500 can be used to protect other orifices, such as… Figure 1 The opening is 117.

[0085] The target material passes through orifice 217 to form flow 121 (510). Flow 121 moves away from orifice 217 along a trajectory. The trajectory can be, for example, in the -X direction, such as... Figure 1 , Figure 3A and Figure 4A As shown. Protective gas 131 flows in a direction away from orifice 217 (520). By flowing away from orifice 217, protective gas 131 prevents or avoids contaminant 150 from reaching orifice 217 and / or forming a layer of contaminant 150 on the outside of nozzle 250. Figure 2A In this way, the protective gas 131 protects the orifice 217 and ensures that the flow 121 is generated in the intended manner. Furthermore, when the vacuum chamber 109 is ventilated and oxygen enters the chamber 109, the flowing protective gas 131 protects the orifice 217. When oxygen enters the chamber 109, metallic materials (such as tin) oxidize and may clog or block the orifice 217. The protective gas 131 serves to keep oxygen away from the orifice 217.

[0086] The protective gas 131 can flow along the outer wall 254. For example, and still referencing Figure 2A The protective gas 131 can flow from the gas guiding system 232 and along the outer wall 254 in the -X direction. The protective gas 131 continues to flow along the nozzle 250 and flows into the vacuum chamber 109 in the -X direction. Therefore, the protective gas 131 flows along the outer wall 254 and away from the orifice 217.

[0087] The protective gas 131 can flow in the open space between the conduit 212 and the inner wall of the outer shell surrounding the conduit. For example, as... Figure 3A As shown, the protective gas 131 can flow in the open space 376, which is located between the outer wall 254 of the conduit 212 and the inner wall 375 of the housing 370.

[0088] Such as about Figure 1 In some implementations, the gas supply device 133 includes more than one chamber 137, and each chamber may include a different gas for use as a protective gas 131. In these implementations, the control system 160 can select a specific one of the chambers 137 to supply the protective gas 131. Figure 5BA process 515 is shown that can be executed together with or independently of process 500. For example, process 515 can be executed after execution (510) and before execution (520). In other examples, process 515 is executed independently of process 500. Process 500 can be executed by one or more electronic processors in electronic processing module 161.

[0089] The state of the EUV light source 100 is determined (516). The state of the EUV light source 100 may be, for example, an operating mode. This state may be, for example, typical operation or a ventilated state. In typical operation, flow 121 is generated as expected, and the vacuum chamber 109 is sealed. In the ventilated state, the vacuum chamber 109 is open and oxygen is present inside. The state of the EUV light source 100 may be determined by, for example, an oxygen sensor in the vacuum chamber 109 or by input made by the operator at the I / O interface 163.

[0090] The protective gas 131 (518) to be used is determined based on the determined state. For example, electronic storage device 162 may store a database or lookup table that stores the relationship between a specific chamber 137 and the possible states of the EUV light source 100. For example, the database may define the relationship between a first chamber 137 and typical operating states, as well as the relationship between different second chambers and ventilation states. The database can be generated and stored when the EUV light source 100 is manufactured or programmed by the operator.

[0091] Control system 160 determines which chamber to couple to fluid connector 134. For example, control system 160 may operate a fluid switch that connects fluid connector 134 to a first chamber 137 during typical operation and to a second chamber during a venting state. In this example, the first chamber 137 may contain molecular hydrogen (H2) gas, and the second chamber may contain argon (Ar) gas. H2 gas has a lower mass than Ar gas. Therefore, in this example, the protective gas 131 has a relatively low mass during typical operation, so that the flow 121 is substantially undisturbed, while it has a relatively high mass during a venting state, so that oxygen is pushed away from the supply system, thereby preventing or reducing oxidation of the components of the supply system.

[0092] Figure 6 and Figure 7 Examples of EUV lithography equipment that can use the aforementioned control system and / or supply system. Figure 8 Examples of EUV light sources that can use the control system and / or supply system described above.

[0093] Figure 6 This is a block diagram of a lithography apparatus 700 including a source collector module SO. The lithography apparatus 700 includes:

[0094] • The irradiation system (irradiator) IL is configured to modulate the radiation beam B (e.g., EUV radiation).

[0095] • A support structure (e.g., a mask stage) MT is configured to support a patterning device (e.g., a mask or a mask plate) MA and is connected to a first locator PM, which is configured to precisely position the patterning device.

[0096] • A substrate stage (e.g., a wafer stage) WT is configured to hold a substrate (e.g., a wafer coated with resist) W and is connected to a second positioner PW, the second positioner PW being configured to precisely position the substrate; and

[0097] • A projection system (e.g., a reflective projection system) PS is configured to project a pattern, which is imparted to the radiation beam B by a patterning device MA, onto a target portion C (e.g., including one or more dies) of a substrate W.

[0098] An irradiation system IL may include various types of optical components for guiding, shaping, or controlling radiation, such as refractive, reflective, magnetic, electromagnetic, electrostatic, or other types of optical components, or any combination thereof.

[0099] The support structure MT holds the patterning device MA in a manner dependent on the orientation of the patterning device, the design of the lithography equipment, and other conditions such as whether the patterning device is held in a vacuum environment. The support structure can use mechanical, vacuum, electrostatic, or other clamping techniques to hold the patterning device. The support structure can be, for example, a frame or table, which can be fixed or movable as needed. The support structure ensures that the patterning device is in the desired position, such as relative to the projection system.

[0100] The term "patterning apparatus" should be interpreted broadly as any apparatus that can be used to pattern a radiation beam in its cross-section to produce a pattern, such as in a target portion of a substrate. The pattern applied to the radiation beam may correspond to a specific functional layer in a device (such as an integrated circuit) produced in the target portion.

[0101] Patterning devices can be transmissive or reflective. Examples of patterning devices include masks, programmable mirror arrays, and programmable LCD panels. Masks are well-known in photolithography and include mask types such as two-phase, alternating phase-shift, and attenuation phase-shift masks, as well as various hybrid mask types. One example of a programmable mirror array employs a matrix arrangement of small mirrors, each of which can be individually tilted to reflect incoming radiation beams in different directions. The tilted mirrors impart a pattern to the radiation beam reflected by the mirror matrix.

[0102] Similar to the illumination system (IL), the projection system (PS) can include various types of optical components, such as refractive, reflective, magnetic, electromagnetic, electrostatic, or other types of optical components, or any combination thereof, depending on the exposure radiation used or other factors such as the use of a vacuum. A vacuum may be required for EUV radiation because other gases may absorb excessive radiation. Therefore, a vacuum environment can be provided throughout the beam path with the help of vacuum walls and a vacuum pump.

[0103] exist Figure 6 and Figure 7 In the example, the device is reflective (e.g., using a reflective mask). The lithography equipment can be of the type having two (dual) or more substrate stages (and / or two or more patterning device stages). In such a "multi-stage" machine, additional stages can be used in parallel, or preparation steps can be performed on one or more stages while exposure is performed using one or more other stages.

[0104] refer to Figure 6 The irradiator IL receives an extreme ultraviolet (EUV) radiation beam from the source collector module SO. Methods for generating EUV light include, but are not limited to, converting a material into a plasma state, the material having at least one element, such as xenon, lithium, or tin, which has one or more emission lines in the EUV range. In one such method, commonly referred to as laser-generated plasma (“LPP”), the desired plasma is generated by irradiating a fuel (such as a droplet, stream, or cluster of material having the desired spectral emission element) with a laser beam. The source collector module SO may be part of an EUV radiation system that includes a laser. Figure 6 Not shown, the laser provides a laser beam for exciting the fuel. The resulting plasma emits output radiation, such as EUV radiation, which is collected using a radiation collector located in the source collector module. The laser and the source collector module can be separate entities, for example, when a carbon dioxide (CO2) laser is used to provide the laser beam for fuel excitation.

[0105] In this case, the laser is considered not to be part of the lithography apparatus, and the radiation beam is delivered from the laser to the source collector module with the aid of a beam delivery system, which includes, for example, suitable directional mirrors and / or beam expanders. In other cases, the source can be part of the source collector module, for example when the source is a discharge-generated plasma EUV generator (often referred to as a DPP source).

[0106] An irradiator IL may include adjusters for regulating the angular intensity distribution of the radiation beam. Typically, at least the outer and / or inner radial ranges of the intensity distribution in the pupil plane of the irradiator (typically referred to as outer σ and inner σ, respectively) can be adjusted. Furthermore, the irradiator IL may include various other components, such as faceted fields and pupil reflector devices. The irradiator IL can be used to regulate the radiation beam to achieve a desired uniformity and intensity distribution in its cross-section.

[0107] A radiation beam B is incident on a patterning device (e.g., a mask) MA held on a support structure (e.g., a mask stage) MT and patterned by the patterning device. After being reflected from the patterning device (e.g., the mask) MA, the radiation beam B passes through a projection system PS, which focuses the beam onto a target portion C of a substrate W. The substrate stage WT can be precisely moved, for example, to position different target portions C within the path of the radiation beam B, by means of a second positioner PW and a positioning sensor PS2 (e.g., an interferometer, a linear encoder, or a capacitive sensor). Similarly, a first positioner PM and another position sensor PS1 can be used to precisely position the patterning device (e.g., the mask) MA relative to the path of the radiation beam B. The patterning device (e.g., the mask) MA and the substrate W can be aligned using patterning device alignment marks M1, M2 and substrate alignment marks P1, P2.

[0108] The described device can be used in at least one of the following modes:

[0109] 1. In step mode, the support structure (e.g., mask stage) MT and substrate stage WT remain substantially stationary while the entire pattern imparting the radiation beam is projected onto the target portion C in one pass (i.e., single static exposure). The substrate stage WT then moves in the X and / or Y directions, allowing different target portions C to be exposed.

[0110] 2. In scanning mode, the support structure (e.g., mask stage) MT and the substrate stage WT are scanned synchronously, while a pattern imparting a radiation beam is projected onto the target portion C (i.e., single dynamic exposure). The velocity and direction of the substrate stage WT relative to the support structure (e.g., mask stage) MT can be determined by the (reduced) magnification and image inversion characteristics of the projection system PS.

[0111] 3. In another mode, the support structure (e.g., mask stage) MT remains substantially stationary to hold the programmable patterning device, while the substrate stage WT is moved or scanned simultaneously as the pattern imparted by the radiation beam is projected onto the target portion C. In this mode, a pulsed radiation source is typically employed, and the programmable patterning device is updated as needed after each movement of the substrate stage WT or between consecutive radiation pulses during scanning. This mode of operation can be readily applied to maskless lithography utilizing programmable patterning devices, such as programmable mirror arrays of the type described above.

[0112] Alternatively, the above usage patterns or combinations and / or variations of completely different usage patterns may be adopted.

[0113] Figure 7 The implementation of the lithography apparatus 700, including the source collector module SO, the irradiation system IL, and the projection system PS, is shown in more detail. The source collector module SO is constructed and arranged such that a vacuum environment can be maintained within a closed structure 720 of the source collector module SO. The systems IL and PS are also housed in their own vacuum environments. The EUV radiation emission plasma 2 can be formed by a laser-generated LPP plasma source. The function of the source collector module SO is to deliver an EUV radiation beam 20 from the plasma 2, focusing it onto a virtual source point. The virtual source point is commonly referred to as the intermediate focus (IF), and the source collector module is arranged such that the intermediate focus IF is located at or near an aperture 721 in the closed structure 720. The virtual source point IF is an image of the radiation emission plasma 2.

[0114] Radiation from the aperture 721 at the central focal point IF passes through the illumination system IL, which in this example includes a faceted field mirror assembly 22 and a faceted pupil mirror assembly 24. These assemblies form a so-called "fly-eye" irradiator, which is arranged to provide a desired angular distribution of the radiation beam 21 at the patterning device MA and a desired uniformity of radiation intensity at the patterning device MA (as indicated by reference numeral 760). When the radiation beam 21 is reflected at the patterning device MA held by the support structure (mask stage) MT, a patterned beam 26 is formed and imaged by the projection system PS via reflective elements 28 and 30 onto the substrate W held by the substrate stage WT. To expose the target portion C on the substrate W, a radiation pulse is generated while the substrate stage WT and the patterning device stage MT perform synchronized movements to scan the pattern on the patterning device MA through the illumination slit.

[0115] Each system IL and PS is arranged in its own vacuum or near-vacuum environment defined by a closed structure similar to the closed structure 720. More elements than are shown can typically be present in the irradiation system IL and projection system PS. Furthermore, more mirrors than are shown can be present. For example, in addition to… Figure 7 As shown, one to six additional reflective elements may be present in the illumination system IL and / or projection system PS.

[0116] Considering the source collector module SO in more detail, a laser energy source, including laser 723, is arranged to deposit laser energy 724 onto a fuel comprising a target material. The target material can be any material that emits EUV radiation when in a plasma state, such as xenon (Xe), tin (Sn), or lithium (Li). Plasma 2 is a highly ionized plasma with an electron temperature of tens of electron volts (eV). Using other fuel materials, such as terbium (Tb) and gadolinium (Gd), higher energy EUV radiation can be generated. The high-energy radiation generated during the deexcitation and recombination of these ions is emitted from the plasma, collected by a near-normal incident collector 3, and focused onto an aperture 721. Plasma 2 and aperture 721 are located at the first and second foci of the collector CO, respectively.

[0117] Although Figure 7 The collector 3 shown is a single-curved mirror, but the collector can take other forms. For example, the collector can be a Schwarzschild collector with two radiation-collecting surfaces. In one embodiment, the collector can be a grazing incidence collector comprising a plurality of substantially cylindrical reflectors nested together.

[0118] To deliver fuel, for example, liquid tin, a droplet generator 726 is arranged within structure 720, configured to emit a stream 728 of fuel droplets toward a desired location of plasma 2. The droplet generator 726 may be, for example, a supply system 110, 210, 310, or 410. In operation, laser energy 724 is delivered synchronously with the operation of the droplet generator 726 to deliver radiation pulses to convert each fuel droplet into plasma 2. The droplet delivery frequency may be several kilohertz, for example, 50 kHz. In practice, the laser energy 724 is delivered in at least two pulses: a pre-pulse of limited energy is delivered to the droplet before it reaches the plasma location to vaporize the fuel material into a small cloud, and then the main pulse of laser energy 724 is delivered to the cloud at the desired location to generate plasma 2. Traps 730 are provided on opposite sides of the enclosed structure 720 to capture fuel that, for any reason, does not become plasma.

[0119] The droplet generator 726 includes a reservoir 701 containing liquid fuel (e.g., molten tin), a filter 769, and a nozzle 702. The nozzle 702 is configured to eject droplets of liquid fuel toward the plasma 2 formation location. Droplets of liquid fuel can be ejected from the nozzle 702 by a combination of pressure within the reservoir 701 and vibrations applied to the nozzle by a piezoelectric actuator (not shown).

[0120] Those skilled in the art will recognize that reference axes X, Y, and Z can be defined for measuring and describing the geometry and behavior of the device, its various components, and the radiation beams 20, 21, 26. Local reference frames for the X, Y, and Z axes can be defined at each part of the device. Figure 7 In the example, the Z-axis at a given point in the system is substantially coincident with the directional optical axis O, and substantially perpendicular to the plane of the patterning device (mask) MA and the plane of the substrate W. In the source-collector module, the X-axis is substantially coincident with the direction of the fuel flow 728, while the Y-axis is orthogonal to it, as shown below. Figure 7 The image points outwards from the page. On the other hand, near the support structure MT that holds the mask MA, the X-axis is generally transverse to the scanning direction aligned with the Y-axis. For convenience, in Figure 7 In the schematic diagram of this region, the X-axis points outside the page, and is marked again. These names are conventional in the art and will be used herein for convenience. In principle, any frame of reference can be chosen to describe the device and its behavior.

[0121] Many additional components used in the operation of the source collector module and lithography apparatus 700 are present as a whole in a typical apparatus, although not shown here. These include arrangements for reducing or mitigating the effects of contamination within a closed vacuum, such as preventing fuel material deposits from damaging or impairing the performance of collector 3 and other optics. Other features present but not described in detail are all the sensors, controllers, and actuators involved in controlling the various components and subsystems of lithography apparatus 700.

[0122] refer to Figure 8 The implementation of the LPP EUV light source 800 is shown. The light source 800 can be used as the source collector module SO in the lithography apparatus 700. Furthermore, Figure 1 The driving laser 815 can be a part of the driving laser 815. The driving laser 815 can be used as a laser 723 ( Figure 7 ).

[0123] The LPP EUV light source 800 is formed by irradiating a target mixture 814 with a magnified beam 810 at a plasma formation location 805, the magnified beam 810 traveling along a beam path toward the target mixture 814. Regarding Figure 1 The target materials and information discussed Figure 1The target in the target stream 121 discussed may be or includes the target mixture 814. The plasma formation location 805 is within the interior 807 of the vacuum chamber 830. When the magnifying beam 810 strikes the target mixture 814, the target material within the target mixture 814 is transformed into a plasma state having emission spectra in the EUV range. The resulting plasma possesses certain characteristics depending on the composition of the target material within the target mixture 814. These characteristics may include the wavelength of the EUV light generated by the plasma and the type and amount of debris released from the plasma.

[0124] The light source 800 includes a driving laser system 815 that generates an amplified beam 810 due to population inversion within one or more gain media of the laser system 815. The light source 800 includes a beam delivery system between the laser system 815 and a plasma formation location 805. The beam delivery system includes a beam transmission system 820 and a focusing assembly 822. The beam transmission system 820 receives the amplified beam 810 from the laser system 815, manipulates and modifies the amplified beam 810 as needed, and outputs the amplified beam 810 to the focusing assembly 822. The focusing assembly 822 receives the amplified beam 810 and focuses the beam 810 onto the plasma formation location 805.

[0125] In some implementations, the laser system 815 may include one or more optical amplifiers, a laser, and / or a lamp to provide one or more master pulses and, in some cases, one or more pre-pulses. Each optical amplifier includes a gain medium capable of optically amplifying a desired wavelength at high gain, an excitation source, and internal optics. The optical amplifier may or may not have a laser mirror or other feedback device forming a laser cavity. Thus, even without a laser cavity, the laser system 815 will generate an amplified beam 810 due to population inversion in the gain medium of the laser amplifier. Furthermore, if a laser cavity is present to provide sufficient feedback to the laser system 815, the laser system 815 can generate an amplified beam 810 as a coherent laser beam. The term "amplified beam" includes one or more of the following: light from the laser system 815 that is only amplified but not necessarily coherent laser oscillation, and light from the laser system 815 that is amplified and is also a coherent laser oscillation.

[0126] The optical amplifier in laser system 815 may include a filling gas as a gain medium, comprising CO2, and may amplify light at a gain of greater than or equal to 800 times at wavelengths between approximately 9100 and approximately 11000 nm, particularly approximately 10600 nm. Suitable amplifiers and lasers for laser system 815 may include pulsed laser devices, such as pulsed gas discharge CO2 laser devices that generate radiation at approximately 9300 nm or approximately 10600 nm, which may operate at relatively high power (e.g., 10 kW or higher) and high pulse repetition rates (e.g., 40 kHz or higher), for example, using DC or RF excitation. The pulse repetition rate may be, for example, 50 kHz. The optical amplifier in laser system 815 may also include a cooling system, such as water, which can be used when operating laser system 815 at higher power.

[0127] The light source 800 includes a collector mirror 835 having an aperture 840 to allow the magnified beam 810 to pass through and reach the plasma formation location 805. The collector mirror 835 may be, for example, an elliptical mirror having a principal focal point at the plasma formation location 805 and a secondary focal point (also called an intermediate focal point) at an intermediate location 845, from which EUV light can be output from the light source 800 and input to, for example, an integrated circuit lithography tool (not shown). The light source 800 may also include a hollow conical shroud 850 (e.g., a gas cone) with open ends, tapering from the collector mirror 835 toward the plasma formation location 805 to reduce the amount of plasma-generating debris entering the focusing assembly 822 and / or the beam delivery system 820, while allowing the magnified beam 810 to reach the plasma formation location 805. For this purpose, an airflow can be provided within the shroud, which is directed toward the plasma formation location 805.

[0128] The light source 800 may also include a main controller 855 connected to the droplet position detection feedback system 856, the laser control system 857, and the beam control system 858. The light source 800 may include one or more target or droplet imagers 860, which provide an output indicating, for example, the droplet position relative to the plasma formation location 805, and provide this output to the droplet position detection feedback system 856. The system 856 can, for example, calculate the droplet position and trajectory, and thereby calculate the droplet position error droplet-by-drop or on average. Therefore, the droplet position detection feedback system 856 provides the droplet position error as input to the main controller 855. Thus, the main controller 855 can provide laser position, direction, and timing correction signals to, for example, the laser control system 857 and / or the beam control system 858. The laser control system 857 can, for example, be used to control a laser timing circuit, and the beam control system 858 can, for example, be used to control the position and shape of the amplified beam of the beam transmission system 820 to change the position and / or focusing power of the beam focus within the chamber 830.

[0129] The supply system 825 includes a target material delivery control system 826, which is operable in response to a signal from a main controller 855 to, for example, modify the release point of droplets released by the target material supply device 827 to correct for errors in the droplets reaching the desired plasma formation position 805.

[0130] Furthermore, the light source 800 may include light source detectors 865 and 870, which measure one or more EUV light parameters, including but not limited to pulse energy, energy distribution as a function of wavelength, energy within a specific wavelength band, energy outside a specific wavelength band, and the angular distribution of EUV intensity and / or average power. Light source detector 865 generates a feedback signal for use by the main controller 855. For example, the feedback signal may indicate errors in parameters such as the timing and focusing of the laser pulse to correctly intercept droplets at the correct position and time, thereby achieving efficient and effective EUV light production.

[0131] The light source 800 may also include a guide laser 875, which can be used to align various portions of the light source 800 or to help direct the amplified beam 810 to the plasma formation position 705. In conjunction with the guide laser 875, the light source 800 includes a measurement system 824, which is placed within a focusing assembly 822 to sample a portion of the light from the guide laser 875 and the amplified beam 810. In other implementations, the measurement system 824 is placed within a beam transmission system 820. The measurement system 824 may include optical elements for sampling or redirecting a subset of the light, such optical elements being made of any material capable of handling the power of the guide laser beam and the amplified beam 810. A beam analysis system is formed by the measurement system 824 and a master controller 855, as the master controller 855 analyzes the sampled light from the guide laser 875 and uses this information to adjust the components within the focusing assembly 822 via a beam control system 858.

[0132] Therefore, in summary, the light source 800 generates an amplified beam 810 guided along the beam path to irradiate the target mixture 814 at the plasma formation location 805, thereby converting the target material within the mixture 814 into plasma that emits light in the EUV range. The amplified beam 810 operates at a specific wavelength (also known as the driving laser wavelength) determined based on the design and characteristics of the laser system 815. Alternatively, the amplified beam 810 can be a laser beam if the target material provides sufficient feedback back to the laser system 815 to generate coherent laser light, or if the driving laser system 815 includes suitable optical feedback to form a laser cavity.

[0133] Other aspects of the invention are set forth in the following numbered clauses.

[0134] 1. A target delivery system for an extreme ultraviolet (EUV) light source, the system comprising:

[0135] A conduit includes an outer conduit region, an inner conduit region, and an end defining an orifice, wherein the inner conduit region is configured to receive target material that emits EUV light when in a plasma state, and the orifice is configured to supply the target material into the interior of a vacuum chamber; and

[0136] A protection system is configured to direct a protective gas away from the end defining the orifice and toward the interior of the vacuum chamber, wherein the flowing protective gas is configured to guide one or more contaminants away from the end defining the orifice.

[0137] 2. The target delivery system according to Clause 1, wherein the protective gas includes an inert gas or a reactive gas.

[0138] 3. The target delivery system according to Clause 1, wherein the protective gas comprises molecular hydrogen (H2).

[0139] 4. The target delivery system according to Clause 1, wherein the protection system is configured to allow the protective gas to flow along the outside of the conduit.

[0140] 5. The target conveying system as described in Clause 4, wherein the protection system comprises:

[0141] The body includes sidewalls that surround at least a portion of the exterior of the conduit, the body defining an open end region aligned with the orifice of the conduit, and wherein...

[0142] The protective gas flows in the open space between the outer side of the conduit and the inner wall of the sidewall, and the protective gas flows through the open end region to exit the body.

[0143] 6. The target delivery system according to Clause 5, wherein the sidewall includes at least one port in fluid communication with the open space, the at least one port being configured to be fluidly coupled to a gas supply device containing the protective gas.

[0144] 7. The target delivery system as described in Clause 1, wherein the protection system includes at least one gas source.

[0145] 8. The target delivery system according to Clause 1, wherein the target delivery system further includes a temperature control block that at least partially surrounds the exterior of the conduit, and the protection system includes a body that surrounds at least a portion of the temperature control block, the body defining an open end region aligned with the orifice of the conduit, and wherein

[0146] The protective gas flows in the open space between the temperature control block and the inner wall of the body, and the protective gas exits the body through the open end region.

[0147] 9. The target delivery system according to Clause 8, wherein the one or more contaminants include mobile substances, and the flowing fluid is configured to reduce the interaction between the one or more mobile contaminants and the end of the conduit by changing the direction of movement of the one or more mobile contaminants away from the end of the conduit.

[0148] 10. The target delivery system according to Clause 1, wherein the one or more contaminants include mobile substances, and the flowing fluid is configured to prevent interaction between the one or more mobile contaminants and the end of the conduit by changing the direction of motion of the one or more mobile contaminants away from the end of the conduit.

[0149] 11. The target delivery system according to Clause 1, wherein the one or more pollutants include one or more of gas, liquid, vapor and particulate matter.

[0150] 12. The target delivery system according to Clause 1, wherein the one or more contaminants include silicon (Si) or silicon dioxide (SiO2).

[0151] 13. The target delivery system according to Clause 1, wherein one or more pollutants include oxygen, water or carbon dioxide (CO2).

[0152] 14. The target delivery system according to Clause 1, wherein the conduit comprises a capillary.

[0153] 15. The target delivery system according to Clause 1, wherein the protection system includes a diffuser device comprising a plurality of openings, each opening being configured to guide the protective gas away from the end defining the orifice.

[0154] 16. The target delivery system according to Clause 15, wherein the plurality of openings surround the exterior of the conduit and are uniformly distributed relative to the exterior of the conduit.

[0155] 17. A method for protecting the orifice of a target material conveying system, the method comprising:

[0156] The target material is supplied through an orifice to provide a flow of targets into the interior of the vacuum chamber, each target in the flow comprising a target material that emits EUV light when in a plasma state; and

[0157] A protective gas is allowed to flow in the target material delivery system and away from the orifice into the interior of the vacuum chamber, the protective gas guiding one or more contaminants away from the orifice.

[0158] 18. The method according to Clause 17, wherein the flowing protective gas does not alter the trajectory of the target flow.

[0159] 19. The method according to Clause 18, wherein the flowing protective gas has a motion component in the direction of travel of the flow along the target.

[0160] 20. The method according to Clause 17, wherein flowing the protective gas includes flowing the protective gas in an open space between the conduit defining the orifice and the body surrounding the conduit.

[0161] 21. The method according to Clause 20, wherein the protective gas flows into the open space at a port in the sidewall and flows out of the space through an open end region defined by the body and aligned with the orifice.

[0162] 22. The method according to Clause 17, wherein the protective gas has a uniform volumetric flow rate at the aperture between the orifice and the interior of the vacuum chamber.

[0163] 23. The method described under Clause 17 further includes:

[0164] Determine the state of the extreme ultraviolet light source, including the target material delivery system; and

[0165] Based on the determined state, determine which of the various protective gases should be used as the protective gas.

[0166] Other implementations are within the scope of the claims.

Claims

1. A target delivery system for an extreme ultraviolet (EUV) light source, the system comprising: The conduit includes an outer conduit region, an inner conduit region, and an end defining an orifice, wherein the inner conduit region is configured to receive a target material that emits EUV light when in a plasma state, and the orifice is configured to supply the target material into the interior of a vacuum chamber. as well as A protection system is configured to direct a protective gas away from the end defining the orifice and toward the interior of the vacuum chamber, wherein the flowing protective gas is configured to guide one or more contaminants away from the end defining the orifice; and A control system that determines which of a variety of protective gases to use as the protective gas based on the state of the EUV light source and the quality of the protective gas.

2. The target delivery system according to claim 1, wherein the protective gas comprises an inert gas or a reactive gas.

3. The target delivery system according to claim 1, wherein the protective gas comprises molecular hydrogen (H2).

4. The target delivery system of claim 1, wherein the protection system is configured to allow the protective gas to flow along the outside of the conduit.

5. The target conveying system according to claim 4, wherein the protection system comprises: The body includes sidewalls that surround at least a portion of the exterior of the conduit, the body defining an open end region aligned with the orifice of the conduit, and wherein... The protective gas flows in the open space between the outer side of the conduit and the inner wall of the sidewall, and the protective gas flows through the open end region to exit the body.

6. The target delivery system of claim 5, wherein the sidewall includes at least one port in fluid communication with the open space, the port being configured to be fluidly coupled to a gas supply device containing the protective gas.

7. The target delivery system according to claim 1, wherein the protection system includes at least one gas source.

8. The target delivery system of claim 1, wherein the target delivery system further comprises a temperature control block that at least partially surrounds the exterior of the conduit, and the protection system comprises a body that surrounds at least a portion of the temperature control block, the body defining an open end region aligned with the orifice of the conduit, and wherein The protective gas flows in the open space between the temperature control block and the inner wall of the body, and the protective gas exits the body through the open end region.

9. The target delivery system of claim 8, wherein the one or more contaminants comprise mobile substances, and the flowing protective gas is configured to reduce the interaction between the one or more mobile contaminants and the end of the conduit by changing the direction of movement of the one or more mobile contaminants away from the end of the conduit.

10. The target delivery system of claim 1, wherein the one or more contaminants comprise mobile substances, and the flowing protective gas is configured to prevent interaction between the one or more mobile contaminants and the end of the conduit by changing the direction of movement of the one or more mobile contaminants away from the end of the conduit.

11. The target delivery system according to claim 1, wherein the one or more pollutants include one or more of gas, liquid and particulate matter.

12. The target delivery system of claim 11, wherein the gas comprises vapor.

13. The target delivery system according to claim 1, wherein the one or more pollutants comprise silicon (Si) or silicon dioxide (SiO2).

14. The target delivery system of claim 1, wherein the one or more pollutants include oxygen, water or carbon dioxide (CO2).

15. The target delivery system of claim 1, wherein the conduit comprises a capillary.

16. The target delivery system of claim 1, wherein the protection system includes a diffuser device comprising a plurality of openings, each opening being configured to guide the protective gas away from the end defining the orifice.

17. The target delivery system of claim 16, wherein the plurality of openings surround the exterior of the conduit and are uniformly distributed relative to the exterior of the conduit.

18. A method for protecting the orifice of a target material conveying system, the method comprising: The target material is passed through an orifice to provide a flow of targets into the interior of the vacuum chamber, each target in the flow comprising target material that emits EUV light when in a plasma state; A protective gas is allowed to flow in the target material delivery system and away from the orifice into the interior of the vacuum chamber, the protective gas guiding one or more contaminants away from the orifice; Determine the state of the extreme ultraviolet light source, including the target material delivery system; as well as Based on the determined state and the quality of the protective gas, it is determined which of the various protective gases to use as the protective gas.

19. The method of claim 18, wherein the flowing protective gas does not alter the flow trajectory of the target.

20. The method of claim 19, wherein the flowing protective gas has a motion component in the direction of travel of the flow along the target.

21. The method of claim 18, wherein causing the protective gas to flow comprises: The protective gas flows in the open space between the conduit defining the orifice and the body surrounding the conduit.

22. The method of claim 21, wherein the protective gas flows into the open space at a port in the body and exits the open space through an open end region defined by the body and aligned with the orifice.

23. The method of claim 18, wherein the protective gas has a uniform volumetric flow rate at the aperture between the orifice and the interior of the vacuum chamber.

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