CN114830832A

CN114830832A - Target material reservoir for extreme ultraviolet light source

Info

Publication number: CN114830832A
Application number: CN202080087548.8A
Authority: CN
Inventors: J·D·特德罗
Original assignee: ASML Holding NV
Current assignee: ASML Holding NV
Priority date: 2019-12-17
Filing date: 2020-11-20
Publication date: 2022-07-29
Also published as: TW202129398A; JP2023506411A; WO2021121852A1

Abstract

An apparatus for an Extreme Ultraviolet (EUV) light source includes a body. The main body includes: a first structure (246) including a first wall; and a second structure (248) comprising a second wall permanently joined to the first wall. An interior (203) of the body is at least partially defined by the first wall and the second wall. The first wall includes a first metallization material and the second wall includes a second metallization material having a different thermal conductivity than the first metallization material. The interior of the body is configured to be fluidly connected to a target supply system of the EUV light source.

Description

Target material reservoir for extreme ultraviolet light source

Of the related applicationCross-referencing

The present application claims priority from U.S. application No. 62/949,144 entitled "target material reservoir FOR EXTREME ULTRAVIOLET LIGHT SOURCE (TARGET MATERIAL TANK FOR EXTREME ULTRAVIOLET LIGHT SOURCE)" filed on 12/17/2019 and U.S. application No. 62/986,266 entitled "target material reservoir FOR EXTREME ULTRAVIOLET LIGHT SOURCE (TARGET MATERIAL TANK FOR EXTREME ULTRAVIOLET LIGHT SOURCE)" filed on 3/6/2020, the entire contents of both applications being incorporated herein by reference.

Technical Field

The present disclosure relates to a target material reservoir for an Extreme Ultraviolet (EUV) light source.

Background

EUV light may be, for example, electromagnetic radiation having a wavelength of 100 nanometers (nm) or less (also sometimes referred to as soft x-rays), and includes, for example, light having a wavelength of 20nm or less, between 5nm and 20nm, or between 13nm and 14nm, and may be used in a lithographic process to produce extremely small features in a substrate (e.g., a silicon wafer) by inducing polymerization in a resist layer.

Methods of generating EUV light include, but are not necessarily limited to, converting a material comprising an element having an emission line in the EUV range (e.g., xenon, lithium, or tin) into a plasma state. In one such method, commonly referred to as Laser Produced Plasma (LPP), the desired plasma may be produced by irradiating a target material as an element, for example in the form of a droplet, plate, ribbon, stream or cluster of material and having an emission line in the EUV range of the plasma state, with an amplified beam, which may be referred to as a drive laser. For this process, plasma is typically generated in a sealed container (e.g., a vacuum chamber) and monitored using various types of metrology equipment.

Disclosure of Invention

In one aspect, an apparatus for an Extreme Ultraviolet (EUV) light source includes a body. The main body includes: a first structure comprising a first wall; and a second structure comprising a second wall permanently joined to the first wall. The interior of the body is at least partially defined by a first wall and a second wall. The first wall includes a first metallization material and the second wall includes a second metallization material having a different thermal conductivity than the first metallization material. The interior of the body is configured to be fluidly connected to a target supply system of an EUV light source.

Implementations may include one or more of the following features.

The first end of the first wall and the second end of the second wall may be permanently joined at a braze joint.

The first metallization material may include molybdenum (Mo), and the second metallization material may include stainless steel.

The apparatus may further include a temperature control system configured to control a temperature of at least one of the first wall and the second wall. The temperature control system may include: a heating system configured to be thermally coupled to the first wall; and a cooling system configured to be thermally coupled to the second wall. The second metallization material may have a lower thermal conductivity than the first metallization material.

The second metallization material may have a lower thermal conductivity than the first metallization material. The first wall may extend from the first end to the second end, and the second wall may extend from the first end to the second end. The first end of the first wall may be brazed to the second end of the second wall. The apparatus may further comprise: an O-ring at a first end of the second wall; and a removable cap configured to be retained at the O-ring.

The second metallization material may have a lower thermal conductivity than the first metallization material. The first wall may extend from the first end to the second end, and the second wall may extend from the first end to the second end. The first end of the first wall may be brazed to the second end of the second wall. The device may further include at least one port extending from the second wall. The at least one port may include a second metallization material. The second metallization material may comprise stainless steel.

The first metallization material may include a first coefficient of thermal expansion and the second metallization material may include a second coefficient of thermal expansion.

The outer side of the first wall may be permanently joined to the inner side of the second wall.

The body may further include a third structure including a third wall. The third wall may include an inner surface and an outer surface. The inner surface of the third wall may be permanently joined to the outer surface of the second wall. The third wall may include a second metallization material. The apparatus may further include a temperature control system configured to control a temperature of at least one of the first wall, the second wall, and the third wall. The second metallization material may have a lower thermal conductivity than the first metallization material. The temperature control system may include: a heating system configured to be thermally coupled to the first wall; and a cooling system configured to be thermally coupled to the second wall and the third wall. The third wall may be between the second wall and the cooling system.

The apparatus may be a target material reservoir configured to hold a target material within the body. When in the plasma state, the target material may emit EUV light.

The device may be a connection assembly. The first structure may include at least a first port and the second structure may include at least a second port. The first port and the second port may be in fluid communication with each other. The apparatus may be configured to provide a fluid path between an external device coupled to the second port and a reservoir coupled to the first port.

In another aspect, an EUV light source includes a target supply system. The object supply system includes: a drop generator configured to produce a target stream; at least one device comprising an interior region configured to be fluidically coupled to a drop generator; and a container configured to receive a target from the drop generator. The target includes a target material that emits EUV light when in a plasma state. The device includes: a first structure comprising a first wall; and a second structure comprising a second wall permanently joined to the first wall. The interior region is at least partially defined by the first wall and the second wall. The first wall includes a first metallization material and the second wall includes a second metallization material having a different thermal conductivity than the first metallization material.

Implementations may include one or more of the following features.

The EUV light source may further include a light source configured to generate a pulse of light having an energy sufficient to convert at least some of the target material in the target into a plasma state in which the target material emits EUV light.

The at least one device may be a target material reservoir configured to hold a target material in the interior region. The target supply system may further comprise at least one valve. The at least one valve may be configured to fluidly connect or fluidly disconnect an interior region of the target material reservoir from the drop generator.

The at least one device may be a connection assembly. The first structure may include at least a first port and the second structure may include at least a second port. The first port and the second port may be in fluid communication with each other. The target provisioning system may further comprise: an external device coupled to the second port; and a reservoir coupled to the first port. The reservoir may be configured to hold a target material in the inner cavity and may be fluidly coupled to the drop generator. The connection assembly may be configured to provide a fluid path between the external device and the reservoir. The external device may be a vacuum system or a gas supply system.

In another aspect, a target supply system for an EUV light source includes: a drop generator configured to produce a target stream; and at least one device comprising an interior region configured to be fluidically coupled to the drop generator. The target includes a target material that emits EUV light when in a plasma state. The device comprises: a first structure comprising a first wall; and a second structure comprising a second wall permanently joined to the first wall. The interior region is at least partially defined by the first wall and the second wall. The first wall includes a first metallization material and the second wall includes a second metallization material having a different thermal conductivity than the first metallization material.

Implementations may include one or more of the following features.

The at least one device may be a target material reservoir configured to hold a target material in the interior region.

The target supply system may further comprise at least one valve. The at least one valve may be configured to fluidly connect or disconnect an interior region of the at least one device from the drop generator.

The at least one device may be a connection assembly. The first structure may include at least a first port and the second structure may include at least a second port. The first port and the second port may be in fluid communication with each other.

Implementations of any of the above techniques may include an EUV light source, system, method, process, apparatus, or device. 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.

Drawings

Fig. 1 is a block diagram of an Extreme Ultraviolet (EUV) light source.

FIG. 2 is a block diagram of a target material reservoir.

Fig. 3 is a block diagram of a metal connection assembly.

FIG. 4 is a block diagram of a target provisioning system.

FIG. 5 is a block diagram of another target provisioning system.

Figure 6A is a cross-sectional view of another target material reservoir in the X-Y plane.

Figure 6B is a cross-sectional view of the target material reservoir of figure 6A in the X-Z plane.

Fig. 6C is a perspective view of the target material reservoir of fig. 6A.

FIG. 7 is a block diagram of another EUV light source.

Detailed Description

Referring to FIG. 1, a block diagram of an Extreme Ultraviolet (EUV) light source 100 is shown. The light source 100 includes a vessel 109 (e.g., a vacuum chamber or container), a light source 105 that generates a light beam 106, and a target supply system 140. The target supply system 140 includes a target material reservoir 144 having an interior region 103 configured to hold a target material. Target supply system 140 also includes a drop generator 142 that receives target material from interior 103 of target material reservoir 144. The target supply system 140 also includes a pressure management system 130.

The target material reservoir 144 is made of more than one metallization material. In the example shown in fig. 1, the target material reservoir 144 includes a first structure 146 and a second structure 148 that are permanently joined at an interface 150. The interface 150 may be, for example, a copper solder interface. The first structure 146 and the second structure 148 are three-dimensional solid structures, each of the first structure 1 and the second structure being made of a different metallization material. As described below, using more than one metallization material to form the target material reservoir 144 enhances the safety and usability of the target material reservoir 144 and allows for a greater number of options for components.

In operational use, the drop generator 142 delivers the target stream 121 to the interior 101 of the vessel 109. The drop generator 142 includes a drop delivery system, such as a nozzle, and may include one or more pressurized containers that include liquid target material delivered from a target material reservoir 144. The interaction of the beam 106 and the target material in the target 121p (one of the targets in the stream 121) at the plasma generation location 123 produces a plasma 196 that emits EUV light 197. Light beam 106 is generated by light source 105 and delivered to interior 101 via light path 107. Plasma 196, generated by the interaction between beam 106 and the target material in target 121p, is supplied to lithography tool 199. The target 121p includes a target material, which is any material having an emission line in the EUV range when in a plasma state. The target material may be, for example, tin, lithium or xenon. Other materials may also be used as target materials. For example, elemental tin may be used as pure tin (Sn); as the tin compound, for example, SnBr4, SnBr2, SnH4 as a tin alloy, for example, a tin-gallium alloy, a tin-indium-gallium alloy, or any combination of these alloys.

The interior 103 of the reservoir 144 is fluidly coupled to the drop generator 142 by a fluid communication connection 155. The fluid communication connection 155 is any type of device, structure, or system that allows the target material to flow from the interior 103 of the reservoir 144 to the drop generator 142. For example, fluid communication connection 155 may be a tube or pipe, or a combination of these elements. The fluid communication connection 155 may be made of any material capable of transmitting the target material. The fluid communication connection 155 may include an adjustment device, such as adjustment device 452a as shown in fig. 4. The regulating device may be configured to control the flow of the target material through fluid communication connection 155 by, for example, opening, closing, or partially blocking fluid communication connection 155. In some embodiments, the conditioning device may include a freeze valve. In other implementations, the target material reservoir 144 is directly adjacent to the drop generators 142 such that the target material reservoir 144 supplies the drop generators 142 with the target material without the use of a fluid communication connection 155.

Referring to fig. 2, a side cross-sectional view of the target material reservoir 244 is shown. The target material reservoir 244 is an implementation of the target material reservoir 144 (fig. 1).

The target material reservoir 244 includes a first structure 246 and a second structure 248. The first structure 246 and the second structure 248 are solid, three-dimensional bodies that partially define an interior region 203 within the target material reservoir 244. The inner region 203 holds a target material mixture 220. The target material mixture 220 includes a target material that emits EUV light when in a plasma state, and may also include various impurities.

The first structure 246 is made of a first metallization material. The second structure 248 is made of a second metallization material. The first metallization material and the second metallization material are different metallization materials. The first metallization material and the second metallization material have different thermal conductivities. The second metallization material may have a lower thermal conductivity than the first metallization material. For example, the first metallization material may be molybdenum (Mo) having a thermal conductivity of 138 watts per meter kelvin at 20 degrees celsius, and the second metallization material may be stainless steel having a thermal conductivity of 14.4 watts per meter kelvin at 20 degrees celsius. As discussed below, this configuration allows the reservoir 244 to operate in a safe and efficient manner, and also provides greater flexibility with respect to the configuration of the various components of the reservoir 244.

Furthermore, the first metallization material and the second metallization material may have different coefficients of thermal expansion. The coefficient of thermal expansion is a material property that defines the extent to which a material expands when heated or contracts when cooled. For example, the first metallization material may be molybdenum, which has a thickness of 4.8 × 10 at 25 degrees celsius ^-6 A coefficient of thermal expansion per kelvin, and the second metallization material may be stainless steel, which has a coefficient of thermal expansion of about 14.4 x 10 ^-6 A second coefficient of thermal expansion per kelvin. Some sealing techniques are not robust enough to prevent or minimize relative movement between two joined metals, each having a different coefficient of thermal expansion under temperature changes. In another aspect, the first wall 216 and the second wall 218 may be joined at the interface 250 by brazing. Brazing forms a sufficiently strong seal to minimize or prevent relative movement between the two joining metals that differ in their coefficients of thermal expansion as temperature changes. In particular, brazing forms a seal that minimizes or prevents relative movement between the first wall 216 and the second wall 218 during temperature changes. This reduces wear at the interface 250 and improves the sealing performance of the interface 250.

The first structure 246 includes a first wall 216 and a base portion 217. The first wall 216 extends from a second end 216b joined to the base portion 217 to a first end 216a in the Y direction. The base portion 217 defines a port 233 that is made of a first metalized material. Port 233 fluidly couples interior region 203 to a fluid communication connection, such as, for example, a target material reservoir connection 455 (fig. 4) or a fluid communication connection 555 (fig. 5). The port 233 allows fluid (e.g., target material) in the interior region 203 to flow from the target material reservoir 244 into the fluid communication connection.

The first wall 216 and the base portion 217 are made of a first metalized material. The second structure 248 includes the second wall 218. The second wall 218 is made of a second metallized material. The second wall 218 extends from the second end 218b to the first end 218a in the Y direction. Each of the first wall 216 and the second wall 218 is a three-dimensional solid body. The first wall 216 and the second wall 218 have substantially the same cross-sectional dimensional shape in the X-Z direction (in the plane perpendicular to the page in the example of fig. 2). For example, the first wall 216 and the second wall 218 may have a circular, square, or rectangular cross-section in the X-Z plane. The reservoir 244 may be, for example, a rectangular parallelepiped or a cylinder. In the example of fig. 2, the first wall 216 and the second wall 218 have substantially the same diameter in the X-Z plane, and the diameters of the

walls

216 and 218 are substantially constant in the Y direction. Other implementations are also possible. For example, the diameter of wall 216 and/or wall 218 in the X-Y plane may vary along the Y direction. Further, in some implementations, the base portion 217 is not part of the first structure 246. In these implementations, the first structure 246 is open at the second end 216 b. For example, the first structure 246 may be approximately hemispherical in shape.

The second wall 218 is permanently joined to the first wall 216 at an interface 250. For example, the first wall 216 and the second wall 218 may be permanently joined by melting a filler metallization material between the first wall 216 and the second wall 218 (the filler metallization material having a lower melting point than the first metallization material and the second metallization material), such that when the filler metallization material cools to a solid form, the first wall 216 and the second wall 218 are permanently joined. This method of permanently bonding the first metallization material to the second metallization material is referred to as brazing. The brazing forms a strong seal that prevents moisture and oxygen from entering the interior region 203. In the example shown in fig. 2, the first end 216a of the first wall 216 is brazed to the second end 218b of the second wall 218 at the interface 250. The interface 250 is a continuous joint such that the reservoir 244 is a single sealed body.

In the example shown in fig. 2, the O-ring 212 is positioned at a first end 218a of the second wall 218. The O-ring 212 is a continuous sheet or ring of rubber or elastomer that surrounds the circumference of the inside of the first end 218a of the second wall 218. O-ring 212 is used to seal top portion 215 to second wall 218. The top portion 215 may be a removable cap (referred to as removable cap 215) configured to be retained at the O-ring 212. The O-ring is thermally compatible with the second metallization material, which is not elevated to the same high temperature as the first metallization material when the target material in a molten state is in the interior 203 of the target material reservoir 244. The O-ring reduces leakage of the target material 220 when the removable lid is closed over the target material reservoir 244. The removable cover 215 allows for the placement of target material in the interior region 203 of the target material reservoir 244. For example, the target material may be placed into the interior area 203 by opening the removable cover 215, placing the target material into the target material reservoir 244, and then resealing the removable cover 215 to the O-ring 212. The removable cover 215 is made of a second metallized material.

The target material reservoir 244 includes a temperature control system 231. The temperature control system 231 controls the temperature of the first wall 216 and/or the second wall 218. By controlling the temperature of the first wall 216 and/or the second wall 218, the temperature control system 231 also controls the temperature in the interior region 203.

Temperature control system 231 includes a heating system 232 configured to be thermally coupled to first wall 216. The heating system 232 may be a plurality of discrete heating elements positioned at different locations relative to the first wall 216, or may be a single heating element. The heating system 232 may be thermally coupled to the first wall 216 by direct physical contact, but this is not required. By heating the first wall 216, the heating system 232 also heats the interior region 203 including the target material 220. This allows the target material 220 to transition to or remain in a molten, fluid, or molten state that enables the target material 220 to flow.

Temperature control system 231 also includes a cooling system 234 configured to be thermally coupled to second wall 218. Cooling system 234 may be a plurality of discrete cooling elements positioned at different locations relative to second wall 218, or may be a single cooling element. For example, the cooling system 234 may include fluid passages within a conduit, such as water or air. The cooling system 234 cools the second wall 218 and the removable cover 215. For example, the cooling system 234 may be cooled to a touch safe temperature of, for example, about 40 ℃ to 50 ℃.

The relatively low thermal conductivity of the second metallization material allows the wall 218 to be cooled to a touch safe temperature. This allows an operator to manipulate the removable lid 215 and interact with the reservoir 214 in a safe manner. For example, the target material 220 may be replenished or installed by opening the cover 215 and placing a solid block of target material in the interior 203. By cooling the removable cover 215 to a touch safe temperature, the replacement procedure can be performed safely and efficiently without reducing the temperature of the first wall 216. Furthermore, the ability to lower the temperature of the second wall 218 (because of its relatively low thermal conductivity) allows a greater amount of material to be used as the O-ring 212. In particular, because the second wall 218 and the removable cover 215 can be cooled to a touch safe temperature, the O-ring 212 does not necessarily have to withstand high temperatures and may be made of a relatively less heat resistant material. Further, because first structure 246 and port 233 are made of a first metallization material, couplers, fasteners, or other coupling devices coupled to port 233 can also be made of the first metallization material.

The target material reservoir 244 also includes a vacuum port 236. Vacuum port 236 is configured to connect to a vacuum system (not shown). This allows the interior region 203 to be maintained at a pressure below atmospheric pressure or at a particular pressure desired by the user.

Referring to fig. 3, a side cross-sectional view of the metal connection assembly 344 is shown. The metal attachment assembly 344 includes a first structure 346, the first structure 346 being permanently attached to a second structure 348 at an interface 350. The first structure 346 and the second structure 348 are solid three-dimensional bodies that at least partially define the interior region 303.

The first structure 346 is made of a first metallization material. The second structure 348 is made of a second metallization material. The first metallization material and the second metallization material are different metallization materials. The first metallization material and the second metallization material have different thermal conductivities. The second metallization material may have a lower thermal conductivity than the first metallization material. Furthermore, the first metallization material and the second metallization material may have different coefficients of thermal expansion. The first metallization material may be, for example, molybdenum, and the second metallization material may be, for example, stainless steel. This provides greater flexibility in the configuration of the various components of the metallic connection component 344, as described below.

The first structure 346 includes a first wall 316. The first wall 316 extends from the second end 316b to the first end 316a in the Y direction. The first structure 346 is open at the second end 316 b. The open second end 316b is labeled 335 in fig. 3 and is referred to as an opening 335. The opening 335 provides a fluid connection point for the metal connection assembly 344. Although in the example shown in fig. 3, the first structure 346 is open at the second end 316b, other implementations are possible. For example, the first structure 346 may include a base portion that defines a port, similar to the base portion 217 and the port 233 of fig. 2.

First wall 316 includes an outer side 316c facing away from interior region 303. The second structure 348 includes a second wall 318. Second wall 318 extends from second end 318b to first end 318 a. Second wall 318 includes an inner side 318c that faces interior region 303. First wall 316 and second wall 318 are three-dimensional solid bodies having substantially equal cross-sectional size and shape in the X-Z plane. For example, the first wall 316 and the second wall 318 may have circular, square, or rectangular cross-sections in planes in and out of the page. The first end 316a of the first wall 316 and the second end 318b of the second wall 318 are permanently joined at the interface 350. The interface 350 may be formed by brazing. In the example of fig. 3, an outer side 316c of the first wall 316 at the first end 316a is brazed directly to an inner side 318c of the second wall 318 at the second end 318b to form the interface 350.

The second structure 348 also includes a top portion 315. The top portion 315 and the second wall 318 define one or more ports 338. The top portion 315 also defines a gas or vacuum port 336. A fluid (such as a gas, a liquid, or a flowable substance including a gas and/or a liquid) can flow through the interior region 303 of the metal connection assembly 344. For example, fluid can flow from port 336 to opening 335 and/or from one or more ports 338 into interior region 303 and through opening 335. The port 336 may be connected to a vacuum system (not shown) configured to control the pressure in the interior region. The port 336 may also be connected to a gas supply system (not shown) that supplies gas to the interior region 303. In the example shown, port 338 includes a gasket 339 that facilitates connecting port 336 to an external device. The port 336 may be connected to an external device, such as, for example, a gas supply system or a vacuum system. The second end 316b of the first wall 316 may be connected to a reservoir or reservoir, such as reservoir 547 (fig. 5).

The configuration of the metal connection assembly 344 allows the port 388 and the port 336 to be made of the same or thermally similar materials used on many external devices. Because the second structure 348, the port 336, and the port 338 are made of a second metallization material, connectors for connecting to the port 338 and/or the port 336 may also be made of the second metallization material. For example, the second metallization material may be stainless steel and the first metallization material may be molybdenum (Mo). Many external devices use stainless steel connectors. In this example, port 338 and port 336 are connected to an external device having a stainless steel connector at the stainless steel-stainless steel interface. In this example, the connection interface is made of two identical metals. This allows the entire assembly to be heated to a relatively high temperature (e.g., 300 ℃ or higher) without degrading the performance of the connector. Furthermore, this is in contrast to some prior systems in which the entire structure (including the ports for connecting to external devices) is made of a metallized material (such as Mo) having a relatively high thermal conductivity that is greater than the thermal conductivity of the materials (e.g., stainless steel) typically used for connectors connecting external devices to the ports. In these prior systems, the connectors of the external devices and ports on the structure are made of different metals, which may lead to degradation of the connections.

Referring to fig. 4, a target provisioning system 440 is shown. The target supply system 440 is an example of a system in which a multi-metal or bi-metal reservoir or device may be used. Target supply system 440 includes priming reservoir 416, target material reservoir 444, reservoir 447, and drop generator 142 (fig. 1). In some embodiments, there may be multiple reservoirs 447, and one or more reservoirs may be pressurized. The target material reservoir 444 is made of two or more different metallization materials and may be, for example, reservoir 144 or reservoir 244. A fluid communication connection 455 fluidly connects the irrigation reservoir 416, the target material reservoir 444, the reservoir 447, and the drop generator 142. Fluid communication connection 455 is an implementation of fluid communication connection 155 (fig. 1). In the example of fig. 4, reservoir 444 is a refill reservoir.

The fluid communication link 455 includes a regulating device 452a between the reservoir 444 and the reservoir 447. The regulating device 452a is configured to regulate, direct, or control the flow of the target material from the target material reservoir 444 to the reservoir 447. In some implementations, the fluid communication connector 455 also includes an adjustment apparatus 452b between the irrigation reservoir 416 and the target material reservoir 444. In implementations that include an adjustment device 452b, the adjustment device 452b is configured to adjust, direct, or control the flow of the target material from the irrigation reservoir 416 to the target material reservoir 444. Each regulating

device

452a, 452b may be, for example, a valve. If each regulating

device

452a, 452b is a valve, the valve may be a fluid valve, which may be, for example, hydraulic, pneumatic, manually operated, solenoid driven, or motor driven. In some implementations, one or both of the

conditioning devices

452a, 452b are or include a freeze valve.

The irrigation reservoir 416 supplies the target material to the target material reservoir 444, and the target material reservoir 444 supplies the target material to the reservoir 447. The reservoir 447 supplies the drop generator 142 with the target material. Target supply system 440 is configured to allow droplet generator 142 to operate when reservoir 444 is replenished. For example, reservoir 444 may be replenished when conditioning apparatus 452 is in a state that prevents target material from flowing between target material reservoir 444 and reservoir 447. During this time, reservoir 416 is primed or target material reservoir 444 is replenished with target material or fluid target material is produced from solid target material. However, reservoir 447 continues to supply the target material to drop generator 142. When the supply of target material in the reservoir 447 is low, the regulating device 452 changes state to allow target material to flow from the target material reservoir 444 to the reservoir 447. The target material flows into reservoir 447 and reservoir 447 is thereby replenished while drop generator 142 continues to produce stream 121 (fig. 1).

The target supply system 440 is one example of a system in which reservoirs made of more than one metallization material may be used, such as reservoir 144 or reservoir 244. Other implementations are also possible. For example, target supply system 440 may include two or more separate reservoirs between target material reservoir 444 and drop generator 142. Two or more reservoirs are fluidly connected to each other via a fluid communication connection 455, and to the drop generator 142 and the target material reservoir 444, and may include an adjustment device between each of these elements. Furthermore, reservoirs made of more than one metal may be used for EUV light sources in a different configuration than that shown in fig. 4. For example, the reservoir may be directly connected to the drop generator 142 such that the bi-metallic or multi-metallic reservoir acts as a reservoir.

Referring to fig. 5, a target provisioning system 540 is shown. The target supply system 540 is another example of a system in which a multi-metal or bi-metal reservoir or device may be used. Target supply system 540 includes target material reservoir 244, metal connection assembly 344, reservoir 547, fluid communication connection 555, and drop generator 142. Fluid communication connection 555 fluidly connects target material reservoir 244, reservoir 547, and drop generator 142. For example, fluid communication connection 555 may be a tube or pipe, or a combination of these elements. In the example of fig. 5, the target material reservoir 244 acts as a refill reservoir. Specifically, the target material reservoir 244 is configured to: when the target in reservoir 547 is in short supply, reservoir 547 is refilled with target material through fluid communication connection 555. The metal connection assembly 344 provides a gas connection to the reservoir 547.

The regulating device 552a is coupled to a fluid communication connection 555 between the reservoir 244 and the reservoir 547. Conditioning device 552b is coupled to a fluid communication connection 555 between reservoir 547 and drop generator 142.

Conditioning devices

552a and 552b are configured to condition, direct, or control the flow of target material from target material reservoir 244 to reservoir 547 and from reservoir 547 to drop generator 142, respectively.

Each of the

regulating devices

552a, 552b may be, for example, a valve. If each of the

regulating devices

552a, 552b is a valve, the valve may be a fluid valve, which may be, for example, hydraulic, pneumatic, manually operated, solenoid driven, or motor driven. In some implementations, each of the

conditioning devices

552a, 552b is or includes a freeze valve.

Fluid communication connection 555 and each of regulating device 552a and regulating device 552b may be made of a first metalized material such that first structure 246 of reservoir 244, fluid communication connection 555, and each of regulating device 552a and regulating device 552b are made of a material that does not adversely affect the target material.

The target material reservoir 244 holds a target material. Target material flows out of target material reservoir 244 through port 233, into fluid communication connection 555, and into reservoir 547. Reservoir 547 supplies the drop generator 142 with the target material. Target supply system 540 allows drop generator 142 to operate while reservoir 244 is replenished. For example, the reservoir 244 may be replenished while the conditioning apparatus 552a is in a state that prevents target material from flowing between the target material reservoir 244 and the reservoir 547. During this time, the target material reservoir 244 is replenished with a solid target material, and a fluid target material is produced from the solid target material. For example, as described above, the top portion 215 of the reservoir 244 may be a removable lid 215. In these implementations, the solid target material is placed in the reservoir 244 by opening the top portion 215, and the lid 215 is resealed to the reservoir 244, which is replenished with the solid target material. However, reservoir 547 may still contain sufficient supply of target and continue to supply the droplet generator 142 with target material. When the supply amount of the target material in the reservoir 547 is low, the regulating device 552a changes state to allow the target material to flow from the target material tank 244 to the reservoir 547. The target material flows into reservoir 547, thereby replenishing reservoir 547 while drop generator 142 continues to produce stream 121 (fig. 1).

The metal connection assembly 344 supplies fluid (e.g., gas, liquid, or liquid including gas) to the reservoir 547 or removes fluid from the reservoir 547. The first structure 346 of the metal attachment assembly 344 is attached to the reservoir 547 with the opening 335 in fluid communication with the interior of the reservoir 547. The port 336 is connected to an external device 551 using a connector 553 made of a second metallization material. Thus, port 336 and connector 553 are made of the same metallization material. The external device may be, for example, a vacuum system or a gas supply. The reservoir 547 may be made of a first metalized material such that the first structure 346 of the metallic connection assembly 344 and the reservoir 547 are made of the same material.

The target supply system 540 is one example of a system in which reservoirs made of more than one metallization material may be used, including the reservoir 244 and the metal connection assembly 344. Other implementations are also possible. For example, target supply system 540 may include two or more separate reservoirs between target material reservoir 244 and drop generator 142. Two or more reservoirs are fluidly connected to each other, to drop generator 142, and to target material reservoir 244 via fluid communication connection 555, and may include an adjustment device between each of these elements. Each of the two or more reservoirs may be connected to one or more of the metal connection assemblies 344 to provide one or more gas connections or vacuum to each of the two or more reservoirs. Furthermore, reservoirs made of more than one metal may be used for the EUV light source in a different configuration than that shown in fig. 5. For example, the reservoir may be directly connected to the drop generator 142 such that the bi-metallic or multi-metallic reservoir acts as a reservoir.

Referring to fig. 6A-6C, another target material reservoir 644 is shown. Figure 6A is a side cross-sectional view of the target material reservoir 644 in the X-Y plane. FIG. 6B is a cross-sectional view of the target material reservoir 644 taken in the X-Z plane along line B-B' of FIG. 6A. Fig. 6C is a perspective view of the target material reservoir 644. The target material reservoir 644 is the same as the target material reservoir 244 (FIG. 2), except that the target material reservoir 644 also includes a third wall 619. The third wall 619 provides an additional barrier between the interior region 203 and the cooling system 234, as described below. The presence of the third wall 619 reduces the thermal gradient across the second wall 218.

The third wall 619 is a three-dimensional solid body. Like the second wall 218, the third wall 619 is made of a second metallization material. The third wall 619 extends in the Y direction from a second end 619b to a first end 619 a. The third wall 619 includes an inner surface 619c and an outer surface 619 d. In the example of fig. 6A-6C, the third wall 619 and the second wall 218 each have a circular cross-sectional shape in the X-Z plane. Other implementations are also possible. For example, the second wall 218 and the third wall 219 may have a square or rectangular cross-section in the X-Z plane.

The inner surface 619c of the third wall 619 may be permanently joined to the outer surface 218c of the second wall 218. For example, portions of the inner surface 619c and the outer surface 218c may be permanently joined by melting a filler metallization material between the third wall 619 and the second wall 218 (the filler metallization material having a lower melting point than the second metallization material), such that when the filler metallization material cools to a solid form, the third wall 619 and the second wall 218 are permanently joined.

The cooling system 234 is thermally coupled to the outer surface 619 d. In some cases, there is a relatively large temperature difference between the interior region 203 and the cooling system 234. This temperature gradient may cause compressive and tensile stresses to be generated on objects (such as second wall 218) between interior region 203 and cooling system 234. Compressive and/or tensile stresses may cause the object to deform. By placing the third wall 619 between the second wall 218 and the cooling system 234, the distance between the interior 203 and the cooling system 234 increases and the thermal gradient decreases. Reducing the thermal gradient reduces the compressive and tensile stresses on the second wall 218, thus reducing the likelihood of deformation of the second wall 218 material.

Referring to fig. 7, an implementation of an LPP EUV light source 700 is shown. LPP EUV light source 700 is one implementation of EUV light source 100 (fig. 1). The EUV light source 700 includes a target supply system 727. The target supply system 727 may include a bi-metallic or multi-metallic target material reservoir, such as the target material reservoir 144 or the reservoir 244.

The LPP EUV light source 700 is formed by irradiating a target mixture 714 with an amplified light beam 710 at a plasma formation region 705, the amplified light beam 710 traveling along a beam path toward the target mixture 714. The target material in the target of stream 121 discussed with respect to fig. 1 may be or include a target mixture 714. Plasma formation region 705 is within interior 707 of vacuum chamber 730. When the amplified light beam 710 impinges on the target mixture 714, the target material within the target mixture 714 is converted to a plasma state having elements with emission lines in the EUV range. The plasma generated has certain characteristics that depend on the target material composition in the target mixture 714. These characteristics may include the wavelength of EUV light generated by the plasma, and the type and amount of debris released from the plasma.

The optical source 700 includes a driven laser system 715, which driven laser system 715 produces an amplified optical beam 710 due to population inversion within one or more gain media of the laser system 715. Light source 700 includes a beam delivery system between laser system 715 and plasma formation region 705 that includes a beam delivery system 720 and a focusing assembly 722. The beam delivery system 720 receives the amplified light beam 710 from the laser system 715 and controls and modifies the amplified light beam 710 as necessary and outputs the amplified light beam 710 to the focusing assembly 722. The focusing assembly 722 receives the amplified light beam 710 and focuses the light beam 710 onto the plasma formation region 705.

In some implementations, the laser system 715 can include one or more optical amplifiers, lasers, and/or lamps for providing one or more main pulses, and in some cases, one or more pre-pulses. Each optical amplifier includes a gain medium capable of optically amplifying a desired wavelength with high gain, an excitation source, and internal optics. The optical amplifier may or may not have a laser mirror or other feedback device that forms the laser cavity. Thus, laser system 715 produces an amplified beam 710 even without a laser cavity due to population inversion in the laser amplifier gain medium. Furthermore, if a laser cavity is present to provide sufficient feedback to laser system 715, laser system 715 can generate amplified light beam 710 as a coherent laser beam. The term "amplified light beam" includes one or more of the following: light from a laser system 715 that is only amplified, but not necessarily coherent laser oscillation; and light from a laser system 715 that is amplified and also coherent laser oscillation.

The optical amplifier in laser system 715 may include a fill gas comprising CO as the gain medium ₂ And can amplify light having a wavelength between about 9100nm and about 11000nm, particularly about 10600nm, with a gain greater than or equal to 900 times. Suitable amplifiers and lasers for use in laser system 715 may include pulsed laser devices, such as pulsed gas discharge CO ₂ A laser apparatus that produces radiation at about 9300nm or about 10600nm, for example with DC or RF excitation, operating at relatively high power (e.g. 10kW or more) and high pulse repetition rate (e.g. 40kHz or more). The pulse repetition rate may be, for example, 50 kHz. The optical amplifier in the laser system 715 may also include a cooling system (such as water) that may be used when operating the laser system 715 at higher power.

The light source 700 includes a collector mirror 735 having an aperture 740 to allow the amplified light beam 710 to pass through and reach the plasma formation region 705. Collector mirror 735 may be, for example, an ellipsoidal mirror having a primary focus at plasma formation region 705, having a secondary focus at intermediate position 745 (also referred to as an intermediate focus) where EUV light may be output from light source 700 and may be input to, for example, an integrated circuit lithography tool (not shown). The light source 700 may also include an open-ended hollow conical shroud 750 (e.g., a gas cone) that tapers from the collector mirror 735 toward the plasma formation region 705 to reduce the amount of plasma-generated debris entering the focusing assembly 722 and/or the beam delivery system 720 while allowing the amplified light beam 710 to reach the plasma formation region 705. For this purpose, a gas flow may be provided in the shield, which is directed towards the plasma formation region 705.

Light source 700 may also include a master controller 755 connected to drop position detection feedback system 756, laser control system 757, and beam control system 758. Light source 700 may include one or more target or drop imagers 760 that provide an output indicative of the location of a drop, for example, relative to plasma formation region 705, and provide this output to drop location detection feedback system 756, which may, for example, calculate drop location and trajectory from which drop location errors may be calculated on a drop-by-drop basis, or on an average. Thus, drop position detection feedback system 756 provides drop position error as an input to master controller 755. Accordingly, the master controller 755 may provide laser position, orientation, and timing correction signals to the laser control system 757, and the laser control system 757 may be used to control the laser timing circuit and/or the beam control system 758 to control the amplified beam position and shape of the beam delivery system 720 to change the position and/or focusing power of the beam focus within the chamber 730.

The supply system 725 includes a target material delivery control system 726 that is operable to modify the release point of droplets released by the target supply system 727, for example, in response to signals from the main controller 755 to correct errors in the droplets directed to reaching the desired plasma formation region 705.

Further, light source 700 may include

light source detectors

765 and 770 that measure one or more EUV light parameters including, but not limited to, pulse energy, energy distribution as a function of wavelength, energy within a particular wavelength band, energy outside a particular wavelength band, and angular distribution of EUV intensity and/or average power. The light source detector 765 generates a feedback signal for use by the master controller 755. For example, the feedback signal may indicate errors in parameters such as timing and focal length of the laser pulses to properly intercept the droplet at the correct position and time for efficient and effective production of EUV light.

The light source 700 may also include a guiding laser 775 that may be used to align various sections of the light source 700 or assist in steering the amplified light beam 710 to the plasma formation region 705. In conjunction with the guiding laser 775, the light source 700 includes a metrology system 724 positioned within the focusing assembly 722 to sample a portion of the light from the guiding laser 775 and the amplified light beam 710. In other implementations, the metrology system 724 is placed within the beam delivery system 720. Metrology system 724 can include optical elements that sample or redirect a subset of the light, such optical elements being made of any material that can withstand the power of the directed laser beam and the amplified light beam 710. The beam analysis system is formed by metrology system 724 and master controller 755, as master controller 755 analyzes the sampled light from guide laser 775 and uses this information to adjust components within focusing assembly 722 through beam control system 758.

Thus, in summary, the light source 700 produces an amplified light beam 710, which light beam 710 is directed along a beam path to irradiate the target mixture 714 at the plasma formation region 705, thereby converting target material within the mixture 714 into a plasma that emits light in the EUV range. The amplified light beam 710 operates at a specific wavelength (also referred to as the drive laser wavelength) determined based on the design and characteristics of the laser system 715. Further, the amplified light beam 710 may be a laser beam when the target material provides sufficient feedback to the laser system 715 to produce a coherent laser, or if the drive laser system 715 includes suitable optical feedback to form a laser cavity.

Implementations of the present disclosure may be further described using the following clauses:

1. an apparatus for an Extreme Ultraviolet (EUV) light source, the apparatus comprising:

a body, comprising:

a first structure comprising a first wall; and

a second structure comprising a second wall permanently joined to the first wall, wherein an interior of the body is at least partially defined by the first wall and the second wall, the first wall comprising a first metalized material and the second wall comprising a second metalized material having a different thermal conductivity than the first metalized material, and wherein

The interior of the body is configured to be fluidly connected to a target supply system of an EUV light source.

2. The apparatus according to clause 1, wherein the first end of the first wall and the second end of the second wall are permanently joined at a braze joint.

3. The apparatus according to clause 1, wherein the first metallization material comprises molybdenum (Mo) and the second metallization material comprises stainless steel.

4. The apparatus of clause 1, further comprising:

a temperature control system configured to control a temperature of at least one of the first wall and the second wall.

5. The apparatus according to clause 4, wherein the temperature control system comprises:

a heating system configured to be thermally coupled to the first wall; and

a cooling system configured to be thermally coupled to the second wall, wherein the second metallization material has a thermal conductivity that is lower than a thermal conductivity of the first metallization material.

6. The apparatus according to clause 1, wherein the second metallization material has a lower thermal conductivity than the first metallization material, the first wall extends from a first end to a second end, the second wall extends from the first end to the second end, the first end of the first wall is brazed to the second end of the second wall, and the apparatus further comprises:

an O-ring at a first end of the second wall; and

a removable cap configured to be retained at the O-ring.

7. The apparatus according to clause 1, wherein the second metallization material has a lower thermal conductivity than the first metallization material, the first wall extends from a first end to a second end, the second wall extends from the first end to the second end, the first end of the first wall is brazed to the second end of the second wall, and the apparatus further comprises:

at least one port extending from the second wall, the at least one port comprising a second metallization material.

8. The apparatus according to clause 7, wherein the second metallized material comprises stainless steel.

9. The apparatus of clause 1, wherein the first metallization material comprises a first coefficient of thermal expansion and the second metallization material comprises a second coefficient of thermal expansion.

10. The device according to clause 1, wherein the outer side of the first wall is permanently joined to the inner side of the second wall.

11. The apparatus according to clause 1, wherein the body further comprises:

a third structure comprising a third wall comprising an inner surface and an outer surface; and

wherein the inner surface of the third wall is permanently joined to the outer surface of the second wall and the third wall comprises a second metalized material.

12. The apparatus of clause 11, further comprising:

a temperature control system configured to control a temperature of at least one of the first wall, the second wall, and the third wall, and wherein a thermal conductivity of the second metallization material is lower than a thermal conductivity of the first metallization material.

13. The apparatus of clause 12, wherein the temperature control system comprises:

a heating system configured to be thermally coupled to the first wall; and

a cooling system configured to be thermally coupled to the second wall and a third wall, wherein the third wall is between the second wall and the cooling system.

14. The apparatus according to clause 1, wherein the apparatus is a target material reservoir configured to hold a target material inside the body, the target material emitting EUV light when in a plasma state.

15. The device according to clause 1, wherein the device is a connection assembly, the first structure comprises at least a first port, the second structure comprises at least a second port, and the first port and the second port are in fluid communication with each other.

16. The apparatus according to clause 15, wherein the apparatus is configured to provide a fluid path between an external device coupled to the second port and a reservoir coupled to the first port.

17. An Extreme Ultraviolet (EUV) light source, comprising:

a target provisioning system, comprising:

a droplet generator configured to generate a target stream, wherein the target comprises a target material that emits EUV light when in a plasma state; and

at least one apparatus comprising an interior region configured to be fluidically coupled to a drop generator, the apparatus comprising:

a first structure comprising a first wall; and

a second structure comprising a second wall permanently joined to the first wall, wherein the interior region is at least partially defined by the first wall and the second wall, the first wall comprising a first metallized material, and the second wall comprising a second metallized material having a different thermal conductivity than the first metallized material; and

a container configured to receive a target from a drop generator.

18. The EUV light source according to clause 17, further comprising a light source configured to generate a light pulse having an energy sufficient to convert at least some target material in a target into a plasma state in which the target material emits EUV light.

19. The EUV light source of clause 17, wherein the at least one device is a target material reservoir configured to hold a target material in the interior region.

20. An EUV light source according to clause 19, wherein the target supply system further comprises at least one valve configured to fluidly connect or fluidly disconnect an interior region of the target material reservoir from the drop generator.

21. The EUV light source according to clause 17, wherein the at least one device is a connection assembly, the first structure comprises at least a first port, the second structure comprises at least a second port, and the first port and the second port are in fluid communication with each other.

22. The EUV light source according to clause 21, wherein the target supply system further comprises:

an external device coupled to the second port; and

a reservoir coupled to the first port, wherein the reservoir is configured to hold a target material in the inner cavity and is fluidically coupled to the drop generator; and

wherein the connection assembly is configured to provide a fluid path between the external device and the reservoir.

23. The EUV light source according to clause 22, wherein the external device is a vacuum system or a gas supply system.

24. A target supply system for an EUV light source, the target supply system comprising:

a first structure comprising a first wall; and

a second structure comprising a second wall permanently joined to the first wall, wherein the interior region is at least partially defined by the first wall and the second wall, the first wall comprising a first metalized material, and the second wall comprising a second metalized material having a different thermal conductivity than the first metalized material.

25. The target supply system of clause 24, wherein the at least one device is a target material reservoir configured to hold a target material in the interior region.

26. The target supply system of clause 24, further comprising at least one valve configured to fluidly connect or disconnect an interior region of the at least one device from the drop generator.

27. The target supply system of clause 24, wherein the at least one device is a connection assembly, the first structure includes at least a first port, the second structure includes at least a second port, and the first port and the second port are in fluid communication with each other.

Other implementations are within the scope of the following claims.

Claims

a body, comprising:

a first structure comprising a first wall; and

The interior of the body is configured to be fluidly connected to a target supply system of the EUV light source.

2. The apparatus of claim 1, wherein the first end of the first wall and the second end of the second wall are permanently joined at a braze joint.

3. The apparatus of claim 1, wherein the first metallization material comprises molybdenum (Mo) and the second metallization material comprises stainless steel.

4. The apparatus of claim 1, further comprising:

5. The apparatus of claim 4, wherein the temperature control system comprises:

a heating system configured to be thermally coupled to the first wall; and

a cooling system configured to be thermally coupled to the second wall, wherein the thermal conductivity of the second metallization material is lower than the thermal conductivity of the first metallization material.

6. The apparatus of claim 1, wherein the thermal conductivity of the second metallization material is lower than the thermal conductivity of the first metallization material, the first wall extends from a first end to a second end, the second wall extends from a first end to a second end, the first end of the first wall is brazed to the second end of the second wall, and the apparatus further comprises:

an O-ring at the first end of the second wall; and

a removable cap configured to be retained at the O-ring.

7. The apparatus of claim 1, wherein the thermal conductivity of the second metallization material is lower than the thermal conductivity of the first metallization material, the first wall extends from a first end to a second end, the second wall extends from a first end to a second end, the first end of the first wall is brazed to the second end of the second wall, and the apparatus further comprises:

at least one port extending from the second wall, the at least one port comprising the second metallization material.

8. The apparatus of claim 7, wherein the second metallization material comprises stainless steel.

9. The apparatus of claim 1, wherein the first metallization material comprises a first coefficient of thermal expansion and the second metallization material comprises a second coefficient of thermal expansion.

10. The device of claim 1, wherein an outer side of the first wall is permanently joined to an inner side of the second wall.

11. The device of claim 1, wherein the body further comprises:

wherein the inner surface of the third wall is permanently joined to an outer surface of the second wall, and the third wall comprises the second metalized material.

12. The apparatus of claim 11, further comprising:

a temperature control system configured to control a temperature of at least one of the first wall, the second wall, and the third wall, and wherein the thermal conductivity of the second metallization material is lower than the thermal conductivity of the first metallization material.

13. The apparatus of claim 12, wherein the temperature control system comprises:

a heating system configured to be thermally coupled to the first wall; and

a cooling system configured to be thermally coupled to the second wall and the third wall, wherein the third wall is between the second wall and the cooling system.

14. The apparatus of claim 1, wherein the apparatus is a target material reservoir configured to hold a target material in the interior of the body, the target material emitting EUV light when in a plasma state.

15. The device of claim 1, wherein the device is a connection assembly, the first structure includes at least a first port, the second structure includes at least a second port, and the first port and the second port are in fluid communication with each other.

16. The apparatus of claim 15, wherein the apparatus is configured to provide a fluid path between an external device coupled to the second port and a reservoir coupled to the first port.

17. An Extreme Ultraviolet (EUV) light source comprising:

an object provisioning system, comprising:

at least one apparatus comprising an interior region configured to be fluidically coupled to the drop generators, the apparatus comprising:

a first structure comprising a first wall; and

a second structure comprising a second wall permanently joined to the first wall, wherein the interior region is at least partially defined by the first wall and the second wall, the first wall comprising a first metalized material, and the second wall comprising a second metalized material having a different thermal conductivity than the first metalized material; and

a container configured to receive the target from the drop generator.

18. An EUV light source as claimed in claim 17 further comprising a light source configured to generate a pulse of light having an energy sufficient to convert at least some of the target material in a target to a plasma state in which the target material emits EUV light.

19. The EUV light source of claim 17, wherein the at least one device is a target material reservoir configured to hold the target material in the interior region.

20. An EUV light source as claimed in claim 19 wherein the target supply system further comprises at least one valve configured to fluidly connect or disconnect the interior region of the target material reservoir from the drop generator.

21. An EUV light source as claimed in claim 17 wherein the at least one device is a connection assembly, the first structure comprises at least a first port, the second structure comprises at least a second port, and the first and second ports are in fluid communication with each other.

22. An EUV light source according to claim 21, wherein the target supply system further comprises:

an external device coupled to the second port; and

a reservoir coupled to the first port, wherein the reservoir is configured to retain the target material in an inner cavity and is fluidly coupled to the drop generator; and

23. An EUV light source according to claim 22, wherein the external device is a vacuum system or a gas supply system.

a first structure comprising a first wall; and

25. The target supply system of claim 24, wherein the at least one device is a target material reservoir configured to hold the target material in the interior region.

26. The target supply system of claim 24, further comprising at least one valve configured to fluidly connect or disconnect the interior region of the at least one device from the drop generator.

27. The target supply system of claim 24, wherein the at least one device is a connection assembly, the first structure includes at least a first port, the second structure includes at least a second port, and the first port and the second port are in fluid communication with each other.