CN118476316A - Container for radiation source - Google Patents

Abstract

A container for an EUV radiation source, the container comprising: a guide portion for guiding the fuel chips from the plasma formation region of the radiation source toward the fuel chip removing device; a wall comprising an opening, wherein at least a portion of the guide is arranged in the opening of the wall so as to define a gap between the guide and the wall; and a gas supply system configured to supply gas into the gap to control heat transfer between the guide and the wall.

Description

Container for radiation source

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to European application 21217092.2 filed on December 22, 2021, the entire contents of which are incorporated herein by reference.

Technical Field

The present invention relates to containers for radiation sources, such as extreme ultraviolet (EUV) radiation sources, and associated apparatus and systems.

Background Art

A lithographic apparatus is a machine configured to apply a desired pattern to a substrate. For example, a lithographic apparatus may be used in the manufacture of integrated circuits (ICs). A lithographic apparatus may, for example, project a pattern at a patterning device (e.g., a mask) onto a layer of radiation-sensitive material (resist) disposed on a substrate.

To project a pattern onto a substrate, a lithographic apparatus may use electromagnetic radiation. The wavelength of this radiation determines the minimum size of a feature that can be formed on the substrate. A lithographic apparatus using extreme ultraviolet (EUV) radiation (having a wavelength in the range of 4 nm to 20 nm, such as 6.7 nm or 13.5 nm) can be used to form smaller features on a substrate than a lithographic apparatus using, for example, radiation having a wavelength of 193 nm.

The lithographic system may comprise a radiation source, a beam delivery system and a lithographic apparatus.The beam delivery system may be arranged to deliver EUV radiation from the radiation source to the lithographic apparatus.

EUV radiation may be generated using plasma. For example, plasma may be generated by directing a laser beam at a fuel in a radiation source. The resulting plasma may emit EUV radiation. A portion of the fuel may become fuel debris, which may accumulate or deposit on one or more components of the radiation source.

Fuel debris deposited on one or more components of the radiation source may lead to contamination of other components of the radiation source. Such contamination may lead to a reduction in the performance of the radiation source (e.g., the quality or power of the EUV radiation generated), which in turn may lead to a degradation in the performance of the associated lithographic apparatus. Ultimately, this may lead to significantly increased downtime of the lithographic apparatus while components of the radiation source are cleaned or replaced.

Summary of the invention

According to a first aspect of the present invention, there is provided a container for an EUV radiation source, the container comprising: a guide portion for guiding fuel debris from a plasma formation region of the EUV radiation source toward a fuel debris removal device; a wall comprising an opening, wherein at least a portion of the guide portion is arranged in the opening of the wall so as to define a gap between the guide portion and the wall; and a gas supply system, the gas supply system being configured to supply gas into the gap to control heat transfer between the guide portion and the wall.

By configuring the gas supply system to supply gas into the gap, the cooling or heating of the guide portion can be controlled and/or improved. For example, when the EUV radiation source generates EUV radiation, it may be desirable to cool the guide portion. Gas may be supplied into the gap to allow the guide portion to be cooled, for example, to a temperature below the melting temperature of a fuel that may be used in the EUV radiation source. In use, fuel fragments may be deposited on the guide portion. By cooling the guide portion to a temperature below the melting temperature of the fuel, dripping, bubbling and/or splashing of liquid fuel fragments may be prevented or reduced. This may result in a reduction in contamination of one or more components of the EUV radiation source.

Additionally or alternatively, when the EUV radiation source generates EUV radiation, the temperature of the guide portion may increase to about 300° C. or greater. This may result in damage and/or corrosion of the guide portion. For example, the guide portion may include a metal material or a metal alloy material, such as stainless steel. Some metal alloy materials (such as stainless steel) may begin to corrode and/or be damaged at temperatures of about 400° C. or higher. For example, when the EUV radiation source generates EUV radiation, by configuring the gas supply system to supply gas into the gap, the cooling of the guide portion may be controlled and/or improved. This may result in a reduction in corrosion and/or damage to the guide portion and/or an increase in the life of the guide portion. For example, when the EUV radiation source does not generate EUV radiation, it may be desirable to heat the guide portion, for example to remove fuel debris from the guide portion.

The container may be or include a vacuum container, a pressure container, a vacuum chamber or a pressure chamber, etc. The container may be configured to enclose a vacuum or low-pressure environment of an EUV radiation source. The term "low-pressure environment" may be considered to include an environment comprising a gas at a pressure lower than atmospheric pressure (e.g., at a pressure between about 100 Pa and 200 Pa).

The gas supply system can be operable between a first configuration and a second configuration. In the first configuration, the gas supply system can be configured to supply gas into the gap, for example, to increase the heat transfer between the guide portion and the wall. In the second configuration, the gas supply system can be configured not to supply gas into the gap, for example, to reduce the heat transfer between the guide portion and the wall. For example, in the second configuration, the gas supply system can be configured to terminate or stop supplying gas into the gap. By operating the gas supply system between the first configuration and the second configuration, the heat transfer between the guide portion and the wall can be controlled. This can allow the cooling or heating of the guide portion to be controlled and/or improved.

For example, when the EUV radiation source generates EUV radiation, the gas supply system can be configured to operate in a first configuration. For example, when the radiation source does not generate EUV radiation, the gas supply system can be configured to operate in a second configuration. The EUV radiation source can include an on state in which EUV radiation is generated. The EUV radiation source can include an off state in which EUV radiation is not generated. The EUV radiation source can operate between an on state and an off state.

The pressure of the gas in the gap when the gas supply system is in the first configuration may be greater than the pressure of the gas in the gap when the gas supply system is in the second configuration. When the gas supply system is in the first configuration, the pressure of the gas in the gap may be between about 10 kPa and 20 kPa. When the gas supply system is in the second configuration, the pressure of the gas in the gap may be between about 100 Pa and 200 Pa.

The gas supply system may be configured to control the pressure of the gas in the gap, for example to control heat transfer between the guide and the wall.The gas supply system may be configured to control the pressure of the gas in the gap based on at least one of the type of gas and the size of the gap.

For example, in use, the wall may be subjected to a cooling source. For example, in use, the guide portion may be subjected to a heating source. The heating source comprises a heating element. The heating element may be configured to heat the guide portion, for example, when the EUV radiation source does not generate EUV radiation. The heating element may be included in a part of the guide portion, or arranged on the guide portion. The guide portion may be arranged in the container so that, for example, in use, the guide portion may be subjected to heat generated at the plasma formation region of the EUV radiation source.

The cooling source may comprise a cooling element. The cooling element may be configured to cool the wall. The cooling element may be comprised in the wall or in a portion of the wall.

By configuring the gas supply system to supply gas into the gap, cooling or heating of the guide, for example by the cooling source or the heating source, respectively, can be controlled or adjusted more precisely. This can reduce or avoid the use of heating elements with increased capacity, for example, to offset the increased cooling capacity of the cooling source. For example, an increase in the capacity of the cooling source may be necessary when the power of the EUV radiation generated by the EUV radiation source increases. By reducing or avoiding the use of heating elements with increased capacity, damage or deformation of one or more components of the radiation source that may be arranged near the heating element can be reduced or avoided.

The gas may include a thermal conductivity between about 0.02 W/mK and 0.18 W/mK at room temperature.

The gas may be selected from at least one of hydrogen, nitrogen and helium.

The container may comprise at least one restriction element or a plurality of restriction elements for maintaining the pressure of the gas in the gap.At least one restriction element, some or all of the restriction elements may be arranged in the gap and/or in or on the wall.

The container may include at least one spacer element or a plurality of spacer elements for maintaining the size of the gap. At least one spacer element or a plurality of spacer elements may be arranged between the guide and the wall. For example, at least one spacer element or a plurality of spacer elements may be arranged on the guide (e.g. a portion thereof) and/or on the wall.

The container may comprise a plurality of inlets for directing the gas into the gap.The plurality of inlets may be part of, comprised in or arranged in the wall.

According to a second aspect of the present invention, there is provided a container for an EUV radiation source, the container comprising: a container module comprising a wall, the wall comprising a first portion and a second portion, wherein a gap is defined between the first portion and the second portion of the wall; and a gas supply system, the gas supply system being configured to supply gas into the gap to control heat transfer between the first portion and the second portion of the wall.

By configuring the gas supply system to supply gas into the gap, the cooling or heating of the first portion of the wall can be controlled and/or improved. For example, when the EUV radiation source generates EUV radiation, it may be desirable to cool the first portion of the wall. Gas may be supplied into the gap to allow the first portion of the wall to be cooled, for example, to a temperature below the melting temperature of a fuel that can be used in the EUV radiation source. In use, fuel fragments may be deposited on the first portion of the wall. By cooling the first portion of the wall to a temperature below the melting temperature of the fuel, dripping, bubbling and/or splashing of liquid fuel fragments may be prevented or reduced. This may result in a reduction in contamination of one or more components of the EUV radiation source. For example, when the EUV radiation source SO does not generate EUV radiation, it may be desirable to heat the first portion of the wall, for example to remove fuel fragments from the first portion of the wall.

The gas supply system can be operable between a first configuration and a second configuration. In the first configuration, the gas supply system can be configured to supply gas into the gap, for example, to increase the heat transfer between the first portion and the second portion of the wall. In the second configuration, the gas supply system can be configured not to supply gas into the gap, for example, to reduce the heat transfer between the first portion and the second portion of the wall. For example, in the second configuration, the gas supply system can be configured to terminate or stop supplying gas into the gap. By operating the gas supply system between the first configuration and the second configuration, the heat transfer between the first portion and the second portion of the wall can be controlled. This can allow control and/or improvement of the cooling or heating of the first portion of the wall.

For example, when the EUV radiation source generates EUV radiation, the gas supply system can be configured to operate in a first configuration. For example, when the EUV radiation source does not generate EUV radiation, the gas supply system can be configured to operate in a second configuration. The EUV radiation source can include an on state in which EUV radiation is generated. The EUV radiation source can include an off state in which EUV radiation is not generated. The EUV radiation source can be operated between an on state and an off state.

The gas supply system may be configured to control the pressure of the gas in the gap, for example to control heat transfer between the first and second portions of the wall. The gas supply system may be configured to control the pressure of the gas in the gap, for example based on at least one of the type of gas and the size of the gap.

The pressure of the gas in the gap when the gas supply system is in the first configuration may be greater than the pressure of the gas in the gap when the gas supply system is in the second configuration. When the gas supply system is in the first configuration, the pressure of the gas in the gap may be between about 10 kPa and 20 kPa. When the gas supply system is in the second configuration, the pressure of the gas in the gap may be between about 100 Pa and 200 Pa.

For example, in use, a first portion of the wall may be subjected to a heating source. A second portion of the wall may be subjected to a cooling source. The heating source comprises a heating element. For example, when the EUV radiation source does not generate EUV radiation, the heating element may be configured to heat the first portion of the wall. The heating element may be part of the first portion of the wall or included in the first portion of the wall. For example, in use, the first portion of the wall may be subjected to heat generated at a plasma formation region of the EUV radiation source. The cooling source may comprise a cooling element. The cooling element may be configured to cool the second portion of the wall. The cooling element may be part of the second portion of the wall or included in the second portion of the wall.

The gas may include a thermal conductivity between about 0.02 W/mK and 0.18 W/mK at room temperature.

The gas may be selected from at least one of hydrogen, nitrogen and helium.

The container may include at least one restriction element or a plurality of restriction elements for maintaining the pressure of the gas in the gap. At least one restriction element, at least some or all of the restriction elements may be arranged in the gap and/or on the wall, for example, on the first part and/or the second part of the wall.

The container may include at least one spacer element or a plurality of spacer elements for maintaining the size of the gap. The at least one spacer element or a plurality of spacer elements may be arranged between the first portion and the second portion of the wall. At least some or all of the at least one spacer element or a plurality of spacer elements may be arranged on the first portion and/or the second portion of the wall.

The container may comprise a plurality of inlets for directing the gas into the gap.The plurality of inlets may be arranged in the wall, for example in the first part and/or the second part of the wall.

The container module may be configured for use in the vicinity of a plasma formation region of an EUV radiation source.For example, the container module may be configured to surround a plasma formation region of an EUV radiation source.

The container module may be configured for use near an intermediate focus of EUV radiation generated by the EUV radiation source.

The containment module may include a guide for directing the fuel debris from the plasma formation region of the EUV radiation source towards the fuel debris removal device.

The container module may comprise a reservoir for collecting fuel from at least one component of the EUV radiation source.The container module may comprise a further reservoir for supplying fuel to at least one component of the EUV radiation source.

According to a third aspect of the present invention, there is provided an EUV radiation source, comprising the container according to the first aspect and/or the second aspect.

According to a fourth aspect of the present invention, there is provided a lithography system, the lithography apparatus comprising an EUV radiation source according to the third aspect and a lithography apparatus.

According to a fifth aspect of the present invention, there is provided a guide portion for use in a container, the guide portion being configured such that when at least a portion of the guide portion is arranged in an opening in a wall of the container, a gap is defined between the wall of the container and the guide portion.

The container may be or include a container for an EUV radiation source. For example, when at least a portion of the guide is arranged in an opening in a wall of the container, the guide may be configured to guide fuel debris from a plasma formation region of the EUV radiation source towards the fuel debris removal device.

The guide portion may include a first portion and a second portion. The first portion of the guide portion may be configured to be arranged in an opening of the wall of the container. The first portion of the guide portion may include a shape corresponding to the shape of the opening of the wall of the container. The guide portion may be configured such that the size or dimensions of the first portion of the guide portion are smaller than the size or dimensions of the opening of the wall of the container. This may allow a gap to be defined or formed between at least the first portion of the guide portion and the opening of the wall of the container.

The guide portion may be configured so that the second portion of the guide portion protrudes or extends from the first portion of the guide portion. For example, the second portion may extend vertically (e.g., substantially vertically) from the first portion. The second portion may include a shape corresponding to the container wall, such as a curved shape. The guide portion may be configured so that when a portion of the guide portion (e.g., the first portion) is arranged in an opening in the wall of the container, the second portion extends parallel to the wall of the container (e.g., substantially parallel to the wall of the container). The guide portion may be configured so that when a portion of the guide portion (e.g., the first portion) is arranged in an opening in the wall of the container, a gap is defined or formed between at least the second portion of the guide portion and the wall of the container.

It will be apparent to those skilled in the art that the various aspects and features of the present invention set out above or below may be combined with various other aspects and features of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings, in which:

FIG1 depicts a lithography system including a lithographic apparatus and a radiation source;

FIG. 2 depicts an exemplary container for use with the radiation source of FIG. 1 ;

FIG3 depicts a cross-sectional view of an exemplary guide and a portion of a wall of the container of FIG2 ;

FIG4 depicts a cross-sectional view of an exemplary guide and a portion of a wall of the container of FIG2 ;

FIG5 depicts a cross-sectional view of an exemplary guide and a portion of a wall of the container of FIG2;

FIG. 6 depicts an exemplary guide for use with the container of FIG. 2 ;

FIG. 7 depicts an exemplary guide for use with the container of FIG. 2 ;

FIG8 depicts an exemplary container module for use in the container of FIG2 with the guide removed;

FIG. 9 depicts an exemplary container module for the container of FIG. 2 , wherein a portion of the guide is disposed in an opening of the wall;

FIG10 depicts a plan view of an exemplary arrangement of a plurality of spacer elements for use in the container of FIG2 ;

FIG11 depicts a cross-sectional view of another exemplary arrangement of a plurality of spacer elements;

12 depicts a cross-sectional view of a first portion of a guide disposed in an opening in the wall of the container of FIG. 2 ;

FIG. 13 depicts a portion of a cross-sectional view of a first portion of a guide disposed in an opening in the wall of FIG. 12 ;

FIG. 14 depicts an exemplary container module for use in the container of the radiation source of FIG. 2 ;

FIG. 15 depicts another exemplary container module for use in the container of the radiation source of FIG. 2 ; and

FIG. 16 depicts another exemplary container module for use in the container of the radiation source of FIG. 2 .

DETAILED DESCRIPTION

Fig. 1 shows a lithographic system comprising a radiation source SO and a lithographic apparatus LA. The radiation source SO is configured to generate an EUV radiation beam B and for supplying the EUV radiation beam B to the lithographic apparatus LA. The lithographic apparatus LA comprises an illumination system IL, a support structure MT configured to support a patterning device MA (e.g. a mask), a projection system PS, and a substrate table WT configured to support a substrate W.

The illumination system IL is configured to condition the EUV radiation beam B before it is incident on the patterning device MA. Furthermore, the illumination system IL may comprise a faceted field mirror arrangement 10 and a faceted pupil mirror arrangement 11. The faceted field mirror arrangement 10 and the faceted pupil mirror arrangement 11 together provide a desired cross-sectional shape and a desired intensity distribution for the EUV radiation beam B. The illumination system IL may comprise other mirrors or arrangements in addition to or instead of the faceted field mirror arrangement 10 and the faceted pupil mirror arrangement 11.

After being so conditioned, the EUV radiation beam B interacts with the pattern forming device MA. As a result of this interaction, a patterned EUV radiation beam B' is generated. The projection system PS is configured to project the patterned EUV radiation beam B' onto the substrate W. To this end, the projection system PS may include a plurality of mirrors 13, 14, which are configured to project the patterned EUV radiation beam B' onto the substrate W held by the substrate table WT. The projection system PS may apply a reduction factor to the patterned EUV radiation beam B', thereby forming an image MA whose features are smaller than corresponding features on the pattern forming device MA. For example, a reduction factor of 4 or 8 may be applied. Although the projection system PS is illustrated in Figure 1 as having only two mirrors 13, 14, the projection system PS may include a different number of mirrors (e.g., six or eight mirrors).

The substrate W may include a previously formed pattern. In this case, the lithographic apparatus LA aligns an image formed by the patterned EUV radiation beam B' with a pattern previously formed on the substrate W.

A relative vacuum, ie a small amount of gas (eg hydrogen) at a pressure well below atmospheric pressure, may be provided in the radiation source SO in the illumination system IL and/or the projection system PS.

The radiation source SO shown in FIG. 1 is, for example, of a type that may be referred to as a laser produced plasma (LPP) source. A laser system 1 (which may, for example, include a CO ₂ laser) is arranged to deposit energy via a laser beam 2 into a fuel provided from, for example, a fuel emitter 3, such as tin (Sn). Although tin is mentioned in the following description, any suitable fuel may be used. The fuel may, for example, be in liquid form and may, for example, be a metal or an alloy. The fuel emitter 3 may include a nozzle configured to direct tin, for example, in the form of droplets, along a trajectory toward a plasma formation region 4. The laser beam 2 is incident on the tin at the plasma formation region 4. The laser energy is deposited into the tin, generating a tin plasma 7 at the plasma formation region 4. During de-excitation and recombination of electrons with ions of the plasma, radiation including EUV radiation is emitted from the plasma 7.

EUV radiation from the plasma is collected and focused by a collector 5. The collector 5 includes, for example, a near normal incidence radiation collector 5 (sometimes more generally referred to as a normal incidence radiation collector). The collector 5 may have a multilayer mirror structure arranged to reflect EUV radiation (e.g., EUV radiation having a desired wavelength such as 13.5 nm). The collector 5 may have an elliptical configuration having two focal points. A first of the focal points may be located at the plasma formation region 4, and a second of the focal points may be located at an intermediate focus 6, as discussed below.

The laser system 1 may be spatially separated from the radiation source SO. In this case, the laser beam 2 may be delivered from the laser system 1 to the radiation source SO by means of a beam delivery system (not shown) comprising, for example, suitable directional mirrors and/or beam expanders, and/or other optical devices. The laser system 1, the radiation system SO and the beam delivery system may together be considered a radiation system.

The radiation reflected by the collector 5 forms the EUV radiation beam B. The EUV radiation beam B is focused at an intermediate focus 6 to form an image at the intermediate focus 6 of the plasma present at the plasma formation region 4. The image at the intermediate focus 6 serves as a virtual radiation source for the illumination system IL. The radiation source SO is arranged such that the intermediate focus 6 is located at or near an opening 8 in an enclosure 9 of the radiation source SO.

The radiation source SO may comprise an on-state, in which EUV radiation is generated. The radiation source SO may comprise an off-state, in which no EUV radiation is generated. The radiation source SO may be operable between an on-state and an off-state.

FIG2 shows an exemplary container 16 for use with the radiation source shown in FIG1 . The container 16 may be part of or included in the radiation source SO. The enclosure 9 shown in FIG1 may be defined by or included in the container 16. The term "container" may be considered to include vacuum containers, pressure vessels, vacuum chambers, or pressure chambers, etc. In other words, the container 16 may be considered to provide a housing for the vacuum or low-pressure environment of the radiation source SO. As described above, the pressure of the gas in the container 16 may be lower than atmospheric pressure. The container 16 may be configured to surround one or more components of the radiation source SO, such as the collector 5 and/or the fuel emitter 3.

The container 16 comprises a guide 18 for guiding the fuel fragments from the plasma formation region 4 of the radiation source SO towards the fuel fragment removal device 20. The fuel fragments may include particle fragments, for example Sn clusters, Sn microparticles, Sn nanoparticles and/or Sn deposits when tin is used as fuel, molecular and/or atomic fragments, such as Sn vapor, _SnHx vapor, Sn atoms, Sn ions. The fuel fragments may be mixed with a gas (for example hydrogen) that may be present in the radiation source SO. The fuel fragment-gas mixture may be guided towards the fragment removal device 20 via the guide 18. The fuel fragment removal device 20 may be configured to separate the fuel fragments (for example at least a portion thereof) from the gas. The fuel fragment removal device 20 may be provided in the form of a scrubber or the like.

The container 16 includes a wall 16a. The wall 16 defines an inner surface of the container 16 or a portion thereof. The wall 16a includes an opening 16e. At least a portion of the guide 18 is arranged in the opening 16e of the wall 16a, so that a gap 22 is defined or formed between the guide 18 and the wall 16a. The container 16 may include a gas supply system 24 for supplying gas into the gap 22 to control heat transfer between the guide 18 and the wall 16a. The gas supply system 24 may be part of or included in a debris mitigation system (not shown), which may be part of the container 16. It will be understood that the term "heat transfer" may be used interchangeably with the term "heat flow".

At least some of the fuel fragments may be deposited on the guide 18, for example, on at least a portion of the guide 18. For example, when the radiation source SO generates EUV radiation, it may be desirable to keep the temperature of the guide 18 below the melting temperature of the fuel. For example, when tin is used as the fuel, it may be desirable to keep the temperature of the guide 18 below 200° C., which is below the melting temperature of tin of about 230° C. This may prevent or reduce contamination of one or more components of the radiation source SO, such as the collector 5. At temperatures above the melting temperature of the fuel, the fuel fragments may become liquid and/or drip or otherwise spray on one or more components of the radiation source SO. The spraying of liquid fuel fragments may be referred to as splashing. The spraying of liquid fuel fragments may be due to the interaction between hydrogen radicals and the liquid fuel fragments. For example, hydrogen (H2) molecules may split into hydrogen radicals due to their absorption of heat and/or EUV radiation or ion collisions. In other words, under the influence of, for example, EUV radiation, a hydrogen plasma may be formed in the radiation source SO. The hydrogen plasma may contain reactive species (H, H ⁺ , etc.), which may be referred to as hydrogen radicals. The hydrogen radicals may remove (e.g., etch) fuel debris from one or more components of the radiation source (e.g., collector 5). However, it has been found that some hydrogen radicals (such as H ⁺ ) may penetrate the liquid fuel debris layer and form hydrogen bubbles within the liquid fuel debris layer. The bubbles may damage the surface, and when one or more bubbles subsequently rupture, fuel debris (e.g., particulate fuel debris) may be ejected or emitted into the radiation source SO. This bubbling or splashing of liquid fuel debris may be considered an important cause of contamination of one or more components of the radiation source (such as collector 5).

By configuring the gas supply system 24 to supply gas into the gap 22, the cooling or heating of the guide portion 18 can be controlled and/or improved. When the radiation source SO generates EUV radiation, it may be desirable to cool the guide portion 18. For example, gas may be supplied into the gap 22 to allow the guide portion 18 to be cooled to below the melting temperature of the fuel (e.g., tin). This in turn may reduce contamination of one or more components of the radiation source SO, for example, by reducing dripping, bubbling, and/or splashing of liquid fuel fragments. When the radiation source is off, for example, when the radiation source SO does not generate EUV radiation, it may be desirable to heat the guide portion 18, as will be described in more detail below.

When the radiation source SO generates EUV radiation, the temperature of the guide portion 18 increases to about 300° C. or more. This may result in damage and/or corrosion of the guide portion 18. For example, the guide portion 18 may include a metal material or a metal alloy material, such as stainless steel. Some metal alloy materials (such as stainless steel) may begin to corrode and/or be damaged at temperatures of about 400° C. or more. By configuring the gas supply system 24 to supply gas into the gap 22, the cooling of the guide portion 18 may be controlled and/or improved, for example when the radiation source SO generates EUV radiation. This may result in a reduction in corrosion and/or damage to the guide portion 18 and/or an increase in the life of the guide portion 18.

The gas supply system 24 can operate between a first configuration and a second configuration. For example, the gas supply system 24 can include a mass flow controller 25. The mass flow controller 25 can include a controllable valve 25a. The mass flow controller 25 can be configured to operate the valve 25a between an open state and a closed state. In the first configuration, the gas supply system 24 can be configured to supply gas into the gap 22, for example to increase the heat transfer between the guide portion 18 and the wall 16a. In other words, in the first configuration of the gas supply system 24, the heat conduction between the guide portion 18 and the wall 16a can be increased. This can, for example, allow cooling of the guide portion 18 when the radiation source SO generates EUV radiation. In the first configuration of the gas supply device 24, the mass flow controller 25 can be configured to operate the valve 25a in an open state. For example, the mass flow controller 25 can be configured to open the valve 25a so that the gas is supplied to the gap 22 at a target mass flow rate. In this embodiment, the target mass flow rate can be in the range of about 8×10 ^-5 kg/s (5l/min). It will be appreciated that in other embodiments, the target mass flow rate may be between about 8×10 ⁻⁵ kg/s (5 1/min) and 0.8 kg/s (50 1/min).

In the second configuration, the gas supply system 24 may be configured not to supply gas into the gap 22, for example to reduce heat transfer between the guide portion 18 and the wall 16a. For example, in the second configuration, the gas supply system 24 may be configured to terminate or stop supplying gas into the gap 22. In the second configuration of the gas supply system 24, the heat conduction between the guide portion 18 and the wall 16a may be reduced, for example, relative to the heat conduction between the guide portion 18 and the wall 16a when the gas supply system 24 is in the first configuration. This may, for example, allow heating of the guide portion 18 when the radiation source SO does not generate EUV radiation. In the second configuration of the gas supply device 24, the mass flow controller 25 may be configured to operate or control the valve to be in a closed state. When the radiation source SO generates EUV radiation, the gas supply system 24 may be configured to operate in the first configuration. When the radiation source SO does not generate EUV radiation, the gas supply system 24 may be configured to operate in the second configuration.

The heat transfer can be expressed by the heat transfer coefficient h:

Where q is the heat flux and ΔT is the temperature difference.

The heat transfer coefficient h of the gas in the gap 22 may depend on the pressure of the gas in the gap 22. The gas supply system 24 may be configured to control the pressure of the gas in the gap 22 to control the heat transfer between the guide portion 18 and the wall 16a. For example, the gas supply system 24 is configured to increase or decrease the pressure of the gas in the gap 22 to increase or decrease the heat transfer coefficient h of the gas in the gap 22. For example, when the gas supply system 24 is in the first configuration, the pressure of the gas in the gap 22 may be greater than the pressure of the gas in the gap 22 when the gas supply system 24 is in the second configuration.

The gas may include a thermal conductivity between about 0.02 W/mK and 0.18 W/mK at room temperature. The gas may include an inert gas. The gas may be selected from at least one of hydrogen, nitrogen, and helium. In an exemplary embodiment, hydrogen may be used as the gas. As described above, hydrogen may have been used in the radiation source SO. However, it will be understood that in other embodiments, other gases may be used, such as nitrogen, helium, or mixtures thereof.

In an embodiment using hydrogen as the gas, when the gas supply system 24 is in the first configuration, the pressure of the gas in the gap 22 may be between about 10 kPa (100 mbar) and 20 kPa (200 mbar). This may result in a heat transfer coefficient h between about 500 W/m ² K and 1500 W/m ² K. For example, when the size of the gap 22 is about 0.25 mm and the pressure of the gas in the gap 22 is about 15 kPa, the heat transfer coefficient h may be about 750 W/m ² K. A reduction in the pressure of the gas in the gap 22 results in a reduction in the heat transfer coefficient h of the gas in the gap 22. When the gas supply system 24 is the second configuration, the pressure of the gas in the gap 22 may be between about 100 Pa (1 mbar) and 200 Pa (2 mbar). This may result in a heat transfer coefficient h between 10 W/m ² K and 100 W/m ² K. For example, when the size of the gap 22 is about 0.25 mm and the pressure of the gas in the gap 22 is about 150 Pa (1.5 millibars), the heat transfer coefficient h can be about 85 W/m ² K. It will be appreciated that in other embodiments, the pressure of the gas in the gap can be different from the exemplary pressures described above. When the gas supply system 24 is operated in the second configuration, the pressure of the gas in the gap 22 decreases and/or reaches equilibrium with the pressure of the gas in the radiation source SO (e.g., the container 16). For example, the pressure of the gas in the radiation source SO (e.g., the container 16) can be between about 100 Pa (1 millibar) and 200 Pa (2 millibars), such as 150 Pa (1.5 millibars). The guide 18 can be arranged in the opening 16e of the wall 16a so that the gap 22 is communicatively coupled to the interior of the radiation source SO (e.g., the interior of the radiation source SO, such as the container 16). For example, the guide 18 can be arranged in the opening 16e of the wall 16a so as to allow some of the gas in the gap 22 to leak or flow into the container 16. In other words, the guide 18 may be arranged in the opening 16e of the wall 16a so as to allow some gas exchange between the gap 22 and the container 16. This may allow the pressure of the gas in the gap 22 to decrease and/or reach equilibrium with the pressure of the gas in the radiation source SO (e.g., container 16), for example, when the gas supply system 24 is in the second configuration. The gas supply system 24 may be configured to control the pressure of the gas in the gap 22, for example, based on the type of gas and/or the size of the gap. For example, gases other than hydrogen may have different thermal conductivities, which may require different pressures of the gas in the gap to produce a desired heat transfer coefficient. However, for example, when the gas supply system is in the first or second configuration, the pressure of the gas other than hydrogen may be selected to be similar or the same as described above to avoid changing the pressure of the gas in the radiation source (e.g., container). Additionally or alternatively, the heat transfer coefficient h of the gas in the gap 22 depends on the size of the gap 22. In this way, when the size of the gap changes, the heat transfer coefficient h of the gas in the gap 22 may also change. The size of the gap 22 may be between about 0.1 mm and 1 mm, such as about 0.25 mm. For example, when the pressure of the gas in the gap 22 is in the range of about 15 kPa, the heat transfer coefficient h may vary between about 1700 W/m ² K and 195 W/m ² K for a size of the gap 22 varying between about 0.1 mm and 1 mm.

Referring to FIG. 2 , the container 16 may be provided in the form of a modular container. For example, the container 16 may include three modules 16b, 16d, 16c. The first module 16b of the container 16 may be arranged near the plasma formation region 4. The first module 16b of the container 16 may be arranged to surround the plasma formation region 4. The second module 16c of the container 16 may be arranged near the intermediate focus 6. The third module 16d of the container 16 may be arranged between the first module 16b and the second module 16c of the container 16. The wall 16a may be included in the third module 16d of the container 16. Each of the first module 16b, the second module 16c, and the third module 16d of the container 16 may include a truncated cone shape. It will be understood that the modules of the container disclosed herein are not limited to having a truncated cone shape. For example, in other embodiments, the modules of the container may each include a cylindrical or polyhedral shape, etc. Additionally or alternatively, it will be understood that the container disclosed herein is not limited to having three modules. For example, in other embodiments, the container may have more or less than three modules. It will be appreciated that the guide 18 may be or define another module of the container 16 .

FIG. 3 shows a cross-sectional view of a portion of the guide 18 and the wall 16a. As can be seen in FIG. 3, a gap 22 is defined between the guide 18 and the wall 16a. For example, in use, the wall 16a may be subjected to a cooling source. The container 16 may include a plurality of cooling elements 26, five of which are shown in FIG. 3. The cooling element 26 may be part of the cooling source or included in the cooling source. It will be understood that in other embodiments, the container may include more or less than five cooling elements. The cooling element 26 may be part of the wall 16a of the container 16 or included in the wall 16a of the container 16. The cooling source may be configured to cool the wall 16a of the container 16. The cooling source may be configured to cool the wall 16a to a temperature below 150°C. For example, the cooling source may be configured to cool the wall 16a to a temperature in the range of about 40°C to 60°C, such as about 50°C. The cooling element 26 may be provided in the form of a coolant channel. The cooling element 26 may be configured to convey a coolant, such as a coolant fluid or gas. For example, the coolant may include water. Wall 16a may comprise a metal material or a metal alloy material. The metal material or metal alloy material may be selected to have a thermal conductivity of about 200 W/mK or greater at room temperature, for example to allow sufficient cooling by a cooling source. In this embodiment, the metal material or metal alloy material may comprise aluminum.

For example, in use, the guide 18 may be subjected to a heating source. The guide 18 may be arranged in the container 16 so that, for example, in use, the guide 18 is subjected to heat generated at the plasma formation region 4 of the radiation source SO. The heat generated at the plasma formation region 4 of the radiation source SO is indicated by the arrows in FIG. 3 . This heat may cause the temperature of the guide 18 to increase, for example, to increase to a temperature higher than the melting temperature of the fuel. This in turn may cause dripping, splashing and/or bubbling of fuel fragments deposited on the guide 18, which may cause contamination of one or more components of the radiation source SO (such as the collector 5). As described above, when EUV radiation is generated by the radiation source SO, the gas supply system 24 may be operated in a first configuration. The gas supply system 24 supplies gas into the gap 22, for example, to increase the heat transfer between the guide 18 and the wall 16a. In other words, by supplying gas in the gap 22, heat can be transferred from the guide 18 to the wall 16a. This may cause the temperature of the guide 18 to decrease. In an example, the heat generated at the plasma formation region 4 is in the range of about 2 kW, and the pressure of the gas in the gap 22 may be between about 10 kPa and 20 kPa. As described above, the pressure of the gas in the gap 22 results in a heat transfer coefficient h between the guide portion 18 and the wall 16a of between about 500 W/m ² K and 1500 W/m ² K. Therefore, the temperature of the guide portion 18 may be reduced to below 150° C., such as between about 70° C. and 120° C. By reducing the temperature of the guide portion 18 below 150° C., dripping, splashing and/or bubbling of fuel debris deposited on the guide portion 18 may be reduced or prevented. This may result in a reduction in contamination of other components of the radiation source SO, such as the collector 5. Additionally or alternatively, by reducing the temperature of the guide portion 18 below 150° C., damage, degradation and/or corrosion of the guide portion 18 may be reduced.

The heating source may include a plurality of heating elements 28, six of which are shown in FIG. 3. The heating element 28 may be part of or included in the guide 18. It will be appreciated that in other embodiments, the guide may include more or less than six heating elements. The heating element 28 may be configured to heat the guide 18, for example when the radiation source SO does not generate EUV radiation. The heating element 28 may be configured to heat the guide 18 during maintenance operations of the radiation source SO, for example to allow fuel debris to be removed from the guide 18 and/or other components of the radiation source SO. The heating source may be configured to heat the guide 18 to a temperature greater than the melting temperature of the fuel. In an embodiment using tin as the fuel, the heating source may be configured to heat the guide 18 to a temperature greater than 230° C. This may allow fuel debris to be removed from the guide 18. As described above, the gas supply system 24 may be configured to operate in a second configuration, for example when the radiation source SO does not generate EUV radiation. In a second configuration, the gas supply system 24 does not supply gas to the gap 22, for example to reduce heat transfer between the guide portion 18 and the wall 16a. In such an example, the pressure of the gas in the gap 22 may be between about 100 Pa and 200 Pa, which may result in a heat transfer coefficient h between about 10 W/m ² K and 100 W/m ² K. In this way, heat transfer between the guide portion 18 and the wall 16a may be reduced, for example to allow the heating element 28 to heat the guide portion 18 to a temperature above the melting temperature of the fuel. For example, when a power of about 2 kW is applied to the heating element 28, the temperature of the guide portion 18 may increase to between about 270° C. and 330° C. This may allow, for example, the removal of fuel debris from the guide portion 18 during maintenance operations of the radiation source SO. For example, the fuel debris may become liquid and drip from the guide portion 18 or parts thereof. The liquid fuel debris may be collected in a reservoir such as a fuel reservoir.

By configuring the gas supply system 24 to supply gas into the gap 22, the cooling or heating of the guide portion 18 may be controlled or adjusted more precisely. This may reduce or avoid the use of heating elements with increased capacity, for example to offset the increased cooling capacity of the cooling source (e.g., cooling element). For example, when the power of the EUV radiation generated by the radiation source SO increases, an increase in the capacity of the cooling source may be necessary. By reducing or avoiding the use of heating elements with increased capacity, damage or deformation of one or more components of the radiation source that may be arranged near the heating element may be reduced or avoided.

FIG4 shows another cross-sectional view of a portion of the guide 18 and the wall 16a. The embodiment shown in FIG4 is similar to the embodiment described above with respect to FIG3. Therefore, any features described above with respect to FIG3 also apply to the embodiment shown in FIG4. In FIG4, the cooling element 26 is omitted for clarity. However, it will be understood that in the embodiment shown in FIG4, the container 16 may include a cooling element 26 as described above.

The container 16 may include at least one restriction element or a plurality of restriction elements 30 for maintaining the pressure of the gas in the gap 22. For example, the restriction element 30 may be configured to reduce the gas flow in and/or along the gap 22 (e.g., into the radiation source SO) to maintain the pressure in the gap 22. For example, when the gas supply system 24 is in the first configuration, the restriction element 30 may be configured to create a pressure difference between the pressure of the gas in the gap 22 and the pressure of the gas in the radiation source SO (e.g., container 16). The restriction element 30 may be provided in the form of a plurality of restriction elements. In the embodiment shown in FIG. 4, the restriction element 30 is arranged in the gap 22. It will be understood that in other embodiments, the restriction element may be arranged in or on other parts of the container, such as in a wall.

In this embodiment, the limiting element 30 can be provided in the form of a corrugated structure 30a. The corrugated structure 30a can be formed of a metal or a metal alloy (such as stainless steel). The corrugated structure 30 can include a plurality of valleys 30b and peaks 30c. The corrugated structure 30a can be configured to reduce the flow of the gas 32 along the gap 22 (for example, in a direction parallel to (for example, substantially parallel to) the wall 16a). For example, the corrugated structure 30a can be configured so that the flow of the gas 32 between the valley 30b and the peak is reduced. However, the corrugated structure 30a can be configured so that some gas can flow between the valley 30b and the peak 30c, for example, flow near the valley 30b and the peak 30c. This can prevent the pressure accumulation or pressure drop in one or more valleys 30b and/or peaks 30c of the corrugated structure 30a. For example, the size of the valley 30b and the peak 30c can be smaller than the size of the gap 22. Gaps 31a may be defined between the corrugated structure 30 (eg, valleys 30b thereof) and the guide 18, and/or gaps 31b may be formed between the corrugated structure 30a (eg, peaks 30c thereof) and the wall 16a.

FIG5 shows another cross-sectional view of a portion of the guide 18 and the wall 16a. The embodiment shown in FIG5 is similar to the embodiment described above with respect to FIG3 and FIG4. Therefore, any features described above with respect to FIG3 and FIG4 also apply to the embodiment shown in FIG5. In FIG5, the cooling element 26 is omitted for clarity. However, it will be understood that in the embodiment shown in FIG5, the container 16 may include a cooling element 26 as described above.

Referring to FIG5 , the container 16 may include a plurality of inlets 34 for directing gas into the gap 22, five of which are shown in FIG5 . It will be appreciated that in other embodiments, the container may include more or less than five inlets. The inlet 34 may be arranged in the wall 16 a. The inlet 34 may be provided in the form of a nozzle that may be arranged to direct the flow of the gas 32 into the gap 22. Although the inlet 34 is shown only in the embodiment shown in FIG5 , it will be appreciated that any features of the inlet 34 may also be applied to the embodiments described above.

In this embodiment, the limiting element 30 can be provided in the form of multiple outlets 30d. The outlet 30d can be a part of the wall 16a. The outlet 30d can be configured to limit the flow of the gas 32 leaving the gap 22, for example, to maintain the pressure in the gap 22. For example, the outlet 30c can be provided in the form of a slit or an orifice, etc. The size of each outlet 30d can be selected so that the flow of the gas 32 from the gap 22 through the outlet 30d is limited or reduced. The outlet 30d can each include a sealing element (not shown), such as a leak sealing element or an O-ring, etc. The outlet 30d can each include a sealing element for reducing or limiting the flow of the gas 32 from the gap 22 through the outlet 30d. This can allow the pressure of the gas in the gap 22 to be maintained. It will be understood that the outlet 30d can be used as a supplement or alternative to the corrugated structure 30a. Although in the above description, the limiting element is described as being provided in the form of a corrugated structure and/or an outlet, it will be understood that in other embodiments, another structure or element can be used to maintain the pressure of the gas in the gap.

6 and 7 show an exemplary guide 18 for use with a container 16. The guide 18 may include a first portion 18a and a second portion 18b. The first portion 18a of the guide 18 may be configured to be arranged in the opening 16e of the wall 16a. The first portion 18a of the guide 18 may be provided in the form of a tubular portion or a conduit. The first portion 18a of the guide 18 may include a shape corresponding to the shape of the opening 16e of the wall 16a. For example, the first portion 18a may include a circular shape, such as a shape having a circular cross-section (e.g., a substantially circular cross-section) or an elliptical cross-section (e.g., a substantially elliptical cross-section). The size or dimensions (e.g., radius and/or circumference) of the first portion 18a of the guide 18 may be smaller than the size or dimensions (e.g., radius and/or circumference) of the opening 16e of the wall 16a of the container 16. This may allow a gap 22 to be defined or formed between at least the first portion 18a of the guide and the opening 16e of the wall 16a of the container 16.

The first portion 18 a of the guide portion 18 may be configured for connection to another conduit (not shown) that may be configured to connect the guide portion 18 to the fuel debris removal device 20 .

The second portion 18b of the guide portion 18 may protrude or extend from the first portion 18a of the guide portion 18. For example, the second portion 18b of the guide portion 18 may extend vertically (e.g., substantially vertically) from the first portion 18a of the guide portion 18. The second portion 18b of the guide portion 18 may include a curved shape that may correspond to (e.g., substantially correspond to) the shape of the wall 16a. For example, when the first portion 18a of the guide portion 18 is arranged in the opening 16e of the wall 16a, the second portion 18b of the guide portion 18 may extend parallel to (e.g., substantially parallel to) the wall 16a of the container 16, such as shown in FIG. 2.

The heating element 28 is schematically represented by the boxes in Figures 6 and 7. Although two boxes 28 are shown in Figures 6 and 7, it will be understood that each box can represent one or more heating elements 28. The heating element 28 can be arranged on the guide portion 18, for example so that when the first part 18a of the guide portion 18 is arranged in the opening 16e of the wall 16a, the heating element 28 is located in the gap 22. For example, the heating element 28 can be arranged on the surface 18c of the guide portion 18. When the first part 18a of the guide portion 18 is arranged in the opening 16e, the gap 22 can be defined between the surface 18c of the guide portion 18 and the wall 16a. The heating element 28 can be arranged on the surface 18c of the guide portion 18 so as to uniformly heat the guide portion 18, for example during maintenance operations of the heating source SO.

8 and 9 show an exemplary container module for use in the container 16 of the radiation source SO shown in FIG2 . The container module shown in each of FIGS. 8 and 9 may be provided in the form of a third container module 16 d as described above with respect to FIG2 . FIG8 shows a third container module 16 d with the guide 18 removed. FIG9 shows a third container module 16 d with the first portion 18 a of the guide 18 arranged in the opening 16 e of the wall 16 a.

The third container module 16d may include an enclosure 36. The enclosure 36 may be configured to surround the wall 16a of the third container module 16d. The enclosure 36 may form an outer surface of the third container module 16d. The enclosure 36 may include an opening 36a. The size and/or shape of the opening 36a of the enclosure 36 may correspond to the size and/or shape of the opening 16e in the wall 16a.

8, the opening 16e of the wall 16a may include a circular shape. For example, the opening 16e may include a circular cross-section (eg, a substantially circular cross-section) or an elliptical cross-section (eg, a substantially elliptical cross-section), or the like.

When the first portion 18a of the guide portion 18 is disposed in the opening 16e of the wall 16a, a gap 22 can be defined between the first portion 18a of the guide portion 18 and the perimeter 16f of the opening 16e in the wall 16a. The gap 22 can extend between the first portion 18a of the guide portion 18 and the opening 36a of the enclosure structure 36 (e.g., the perimeter thereof). The gap 22 can also be defined between the second portion 18b of the guide portion 18 and the wall 16a (e.g., the portion 16g of the wall 16a), which can be best seen in Figure 2. The gap 22 can extend between the second portion 18b of the guide portion 18 and the wall 16a (e.g., the portion 16g thereof).

9, when the first portion 18a of the guide portion 18 is disposed in the opening 16e of the wall 16a, the first portion 18a of the guide portion 18 may protrude from the wall 16a in an outward direction. The first portion 18a of the guide portion 18 may also protrude from the enclosure 36 in an outward direction. This may facilitate connection of the guide portion 18 with another conduit and/or the fuel debris removal device 20.

FIG. 10 shows a plan view of an exemplary arrangement 42 of a plurality of spacer elements 40 for use in a container 16. A plurality of spacer elements 40 may be a part of a container 16 or included in the container 16. A plurality of spacer elements 40 may be configured to maintain the size of the gap 22. For example, the spacer elements 40 may be configured to control the size of the gap 22. The spacer elements 40 are configured to determine the tolerance of the size of the gap 22, for example, during the manufacture of the guide 18 and/or the third container module 16. As described above, the size of the gap 22 may be between about 0.1 mm and 1 mm, such as about 0.25 mm. For example, the spacer elements 40 may be a part of the wall 16 a. Alternatively or additionally, the spacer elements 40 may be a part of the guide 18.

Referring to FIG. 10 , the arrangement 42 of the spacer elements 40 may be arranged on the wall 16a, for example, opposite the second portion 18b of the guide 18. For example, when the first portion 18a of the guide 18 is arranged in the opening 16e of the wall 16a, the arrangement 42 of the spacer elements 40 may be arranged on the portion 16g of the wall 16a, which may be opposite the second portion 18b of the guide 18, as shown in FIG. 2 . The spacer elements 40 may be arranged on the wall 16a to extend into the gap 22 and face the second portion 18b of the guide 18. The arrangement 42 of the spacer elements 40 may include an inlet 34 and an outlet 30d as described above. The inlet 34 may be arranged between at least two of the spacer elements 40. For example, the inlet 34 may be arranged equidistantly between the spacer elements 40. It will be understood that in other embodiments, the inlet may be arranged differently. The outlet 30d may be arranged around the spacer elements 40 and the inlet 34. For example, the outlets 30d may be arranged on the perimeter 42a of the arrangement 42. However, it will be appreciated that in other embodiments the outlets may be arranged differently.

FIG. 11 shows a cross-sectional view of another exemplary arrangement 44 of the spacer element 40. The arrangement 44 shown in FIG. 11 may include any features of the arrangement 42 shown in FIG. 10. However, it will be understood that the arrangement 44 of the spacer element 40 shown in FIG. 11 may find applicability in different parts of the wall 16a. For example, the spacer element 40 may be arranged between the first part 18a of the guide 18 and the opening 16e of the wall 16a. The spacer element 40 may be arranged on the periphery 16f of the opening 16e. The spacer element 40 may be arranged on the wall 16a, for example, on the periphery 16f of the opening 16e, for example, so as to extend toward the interior or center of the opening 16e, as will be described below. It will be understood that in other embodiments, the spacer element may be additionally or alternatively arranged on the guide.

In the exemplary embodiment shown in Figures 10 and 11, each spacer element 40 can be arranged in the form of a circular or semicircular structure, such as a bead. However, it will be understood that in other embodiments, each spacer element can have a different shape. The dimension G of the gap 22 is indicated in Figure 11. The height H of each spacer element 40 can be determined by one or more manufacturing tolerances of the dimension G of the gap 22. However, it will be understood that the height H of each spacer element 40 can correspond to the minimum value of the allowable dimension G of the gap 22. Although a plurality of spacer elements are described above, it will be understood that in other embodiments, the container can include a single or at least one spacer element.

The container 16 may include a fastening element 46 for fastening the guide 18 to the wall 16a. The fastening element 46 may be configured to removably fasten the guide 18 to the container 16, such as to removably fasten the guide 18 to the wall 16a. For example, the fastening element 46 may be provided in the form of a bolt and nut arrangement, or a bolt and bolt hole arrangement, etc. Although only one fastening element 46 is shown in FIG. 11 , it will be understood that the container may include more than one fastening element for fastening the guide to the container (e.g., a wall).

Fig. 12 shows a cross-sectional view of the first part 18a of the guide 18 arranged in the opening 16e of the wall 16a. The first part 18a of the guide 18 can be arranged concentrically in the opening 16e of the wall 16a. In the exemplary embodiment shown in Fig. 12, three inlets 34 are provided in the wall 16a.

Fig. 13 shows a portion of a cross-sectional view of the first portion 18a of the guide portion 18 arranged in the opening 16e of the wall 16a shown in Fig. 12. A spacing element 40 may be arranged between the first portion 18a of the guide portion 18a and the opening 16e of the wall 16a. By arranging the spacing element 40 between the first portion 18a of the guide portion 18 and the opening 16e of the wall 16a, in use, the spacing element 40 may apply tension or pre-tension to the first portion 18a of the guide portion 18 and/or prevent at least the first portion 18a of the guide portion 18 from expanding.

The spacing element 40 may be arranged between the first portion 18a of the guide 18a and the opening 16e of the wall 16a, for example so as to extend towards the center of the opening 16e. The spacing element 40 may be arranged circumferentially on the periphery 16f of the opening 16e of the wall 16a. It will be appreciated that in other embodiments, the spacing element may be additionally or alternatively arranged on the guide, for example on the first portion and/or the second portion of the guide.

FIG14 shows an exemplary container module 48 for use in a container (such as the container 16 of the radiation source SO shown in FIG2 ). As described above, the container module 48 may be provided in the form of a third container module 16 d. Therefore, any features described above with respect to the third container module 16 d may also be applied to the container module 48 shown in FIG14 .

The container module 48 includes a wall 50, which includes a first portion 50a and a second portion 50b. The first portion 50a of the wall 50 can be provided in the form of an inner wall of the container module 48. The second portion 50b can be provided in the form of an outer wall of the container module 48. A gap 52 is defined between the first portion 50a and the second portion 50b of the wall 50. In the exemplary embodiment shown in Figure 14, the container module 48 includes a guide 18, which is used to guide fuel fragments from the plasma formation region 4 of the radiation source SO toward the fuel fragment removal device 20, as described above. However, it will be understood that in other embodiments, the container module may not include a guide. The wall 50 may include an opening 50c. At least a portion of the guide 18 is arranged in the opening 50c of the wall, for example, so that the gap 52 extends between the guide 18, the first portion 50a of the wall 50, and the second portion 50b. The second portion 50b of the wall 50 may include any of the features of the wall 16a described above.

The container module 48 can be configured to be connected to the gas supply system 24. In this embodiment, the gas supply system 24 can be configured to supply gas into the gap 52 to control the heat transfer between the first portion 50a and the second portion 50b of the wall 50. The gas supply system 24 shown in Figure 14 can include any of the features of the gas supply system described above. It will be understood that in other embodiments, the gas supply system can be part of the container module or included in the container module.

As described above, the gas supply system 24 may be operable between a first configuration and a second configuration. The gas supply system 24 may include a mass flow controller 25. The mass flow controller 25 may include a controllable valve 25a. The mass flow controller 25 may be configured to operate the valve 25a between an open state and a closed state. In the first configuration, the gas supply system 24 may be configured to supply gas to the gap 52, for example, to increase the heat transfer between the first part 50a and the second part 50b of the wall 50. In other words, in the first configuration of the gas supply system 24, the heat conduction between the first part 50a and the second part 50b of the wall 50 may be increased. In the first configuration of the gas supply device 24, the mass flow controller 25 may be configured to operate the valve in an open state. For example, the mass flow controller 25 may be configured to open the valve 25a so that the gas is supplied to the gap 52 at a target mass flow rate.

In the second configuration, the gas supply system 24 may be configured to terminate the supply of gas into the gap 52, for example to reduce the heat flow between the first portion 50a and the second portion 50b of the wall 50. In other words, in the second configuration, the gas supply system 24 may be configured not to supply gas into the gap 52. In the second configuration of the gas supply system 24, the heat conduction between the first portion 50a and the second portion 50b may be reduced, for example, relative to the heat conduction between the first portion 50a and the second portion 50b of the wall 50 when the gas supply system 24 is in the first configuration. In the second configuration of the gas supply device 24, the mass flow controller 25 may be configured to operate or control the valve to be in a closed state. When the radiation source SO generates EUV radiation, the gas supply system 24 may be operated in the first configuration. When the radiation source SO does not generate EUV radiation, the gas supply system 24 may be operated in the second configuration.

The heat transfer coefficient of the gas in the gap 52 may depend on the pressure of the gas in the gap 52. The gas supply system 24 may be configured to control the pressure of the gas in the gap 52 to control the heat transfer between the first portion 50a and the second portion 50b of the wall. For example, the gas supply system 24 may be configured to increase or decrease the pressure of the gas in the gap 52 to increase or decrease the heat transfer coefficient h of the gas in the gap 52. For example, when the gas supply system 24 is in the first configuration, the pressure of the gas in the gap 52 may be greater than the pressure of the gas in the gap 52 when the gas supply system 24 is in the second configuration. For example, when the gas supply system 24 is in the first configuration, the pressure of the gas in the gap 52 may be between about 10kPa and 20kPa. For example, when the gas supply system 24 is in the second configuration, the pressure of the gas in the gap 52 may be between about 100Pa and 200Pa. The pressure of the gas in the gap 52 may depend on the size of the gap 52 and/or the type of gas. The gas may include a thermal conductivity between about 0.02W/mK and 0.18W/mK at room temperature. The gas may include an inert gas. The gas may be selected from at least one of hydrogen, nitrogen and helium. In an exemplary embodiment, hydrogen may be used as the gas. As described above, hydrogen may have been used in the radiation source SO. However, it will be appreciated that in other embodiments, another gas may be used, such as nitrogen, helium or a mixture thereof.

As described above, for example, in use, the wall 50 may be subjected to a cooling source. The container module 48 may include a plurality of cooling elements. The cooling element may be part of the cooling source or included in the cooling source. The cooling element may be part of the second portion 50b of the wall 50 or included in the second portion 50b of the wall 50. The cooling element of the container module 48 may include any of the features of the cooling element 26 described above.

For example, in use, the first portion 50a of the wall 50 may be subjected to a heating source. For example, in use, the first portion 50a of the wall 50 may be subjected to heat generated at the plasma formation region 4 of the radiation source SO. The heat may cause the temperature of the first portion 50a of the wall 50 to increase to above the melting temperature of the fuel. As described above, this in turn may cause dripping, splashing and/or bubbling of fuel debris deposited on the first portion 50a of the wall 18, which may cause contamination of one or more components (such as the collector 5) of the radiation source SO. As described above, when the radiation source is turned on, the gas supply system 24 may operate in a first configuration. The gas supply system 24 supplies gas into the gap 52, for example, to increase heat transfer between the first portion 50a and the second portion 50b of the wall 50. In other words, by supplying gas in the gap 22, heat can be transferred from the first portion 50a of the wall 50 to the second portion 50b. This can cause the temperature of the first portion 50a of the wall 50 to decrease, for example, to below the melting temperature of the fuel. By lowering the temperature of the first portion 50a of the wall below the melting temperature of the fuel, dripping, splashing and/or foaming of fuel debris deposited on the first portion 50a of the wall can be reduced or prevented. This can result in reduced contamination of other components of the radiation source SO, such as the collector 5.

The heating source may include a heating element 28. The heating element 28 may be part of or included in the first portion 50a of the wall 50. For example, when the radiation source SO does not generate EUV radiation, the heating element 28 may be configured to heat the first portion 50a of the wall 50. The heating element 28 may heat the guide 18 during maintenance operations of the radiation source SO, for example to allow fuel debris to be removed from the first portion 50a of the wall and/or other components of the radiation source SO. The heating element 28 may be configured to heat the first portion 50a of the wall 50 to a temperature greater than the melting temperature of the fuel. In an embodiment using tin as the fuel, the heating source may be configured to heat the first portion 50a of the wall to a temperature greater than 230°C. This may allow fuel debris to be removed from the first portion 50a of the wall 50. As described above, when the radiation source SO does not generate EUV radiation, the gas supply system 24 may be configured to operate in a second configuration. In a second configuration, the gas supply system 24 may not supply gas to the gap 52, for example to reduce heat transfer between the first portion 50a and the second portion 50b of the wall 50. This may allow the heating element 28 to heat the first portion 50a of the wall 50 to a temperature above the melting temperature of the fuel. This in turn may allow, for example, the removal of fuel debris from the first portion 50a of the wall 50 during maintenance operations of the radiation source SO. For example, the fuel debris may become liquid and drip from the first portion 50 of the wall or portions thereof. The liquid fuel debris may be collected in a reservoir such as a fuel reservoir.

It will be appreciated that the container module 48 may include any of the features of the restriction element, inlet and/or spacing element as described above. For example, the restriction element may be disposed in the gap 52 and/or in the second portion 50b of the wall 50. The inlet may be disposed in the second portion 50b of the wall 50. The spacing element may be disposed on the first portion 50a and/or the second portion 50b of the wall 50, for example such that the spacing element extends into the gap 52, as described above.

Although the container module 48 has been described herein as being provided in the form of the third container module 16d, it will be appreciated that in other embodiments the container module may be provided in the form of the first module 16b or the second module 16c.

Figure 15 shows another exemplary container module 48 for use in a container of a radiation source SO. In the embodiment shown in Figure 15, the container module 48 is provided in the form of the first container module 16b described above.

Figure 16 shows another exemplary container module 48 for use in a container of a radiation source SO. In the embodiment shown in Figure 16, the container module 48 is provided in the form of the second container module 16c described above.

It will be understood that, as shown in FIG. 2, each of the first container module 16b, the second container module 16c, and the third container module 16d of the container 16 may include the features of the container module 48. In some embodiments, the gaps of the modules may be communicated with each other. In other words, the container 16, such as the first container module 16b, the second container module 16c, and/or the third container module 16d, may be configured so as to allow the gap 52 of one container module in the first container module 16b, the second container module 16c, and the third container module 16d to exchange gas with the gap 52 of at least one other container module in the first container module 16b, the second container module 16c, and the third container module 16d. In other embodiments, the container 16, such as the first container module 16b, the second container module 16c, and/or the third container module 16d, may be configured so that the gap of one container module in the first container module 16b, the second container module 16c, and the third container module 16d and the gap of at least one other container module in the first container module 16b, the second container module 16c, and the third container module 16d are prevented from exchanging gas between the gap. The first container module 16b, the second container module 16c and/or the third container module 16d can be configured to allow gas exchange between the gap 52 of at least one of the first container module 16b, the second container module 16c and the third container module 16d and the radiation source SO (e.g., container 16), for example to reduce the pressure in the gap 52 when the gas supply system 24 is in the second configuration.

Although in the above description, the container module 48 can be provided in the form of the first container module 16b, the second container module 16c and/or the third container module 16d, it will be understood that the present disclosure is not limited thereto. For example, it will be understood that in other embodiments, the container module can be provided in the form of a storage for supplying fuel to the radiation source. The container module can be provided in the form of another storage for collecting fuel from the radiation source.

Although in the above description, the gas supply system operates in the first configuration when radiation is generated by the radiation source, it will be understood that in other embodiments, the gas supply system may additionally or alternatively operate in the first configuration when the radiation source does not generate radiation. Additionally or alternatively, the gas supply system may operate in the second configuration when radiation is generated by the radiation source.

Although hydrogen is used as the gas in the above description. It will be appreciated that in other embodiments, gases other than hydrogen may be used. For example, in other embodiments, the gas may include helium, nitrogen, or a mixture thereof. In such other embodiments, for example when the gas supply system is in the first or second configuration, the pressure of the gas in the gap may be similar, the same, or different from the exemplary pressures disclosed herein.

Although specific reference may be made herein to the use of lithographic apparatus in IC manufacturing, it should be understood that the lithographic apparatus described herein may have other applications. Possible other applications include the manufacture of integrated optical systems, guidance and detection patterns for magnetic domain memories, flat panel displays, liquid crystal displays (LCDs), thin film magnetic heads, etc.

Although specific embodiments of the present invention have been described above, it will be appreciated that the present invention may be practiced in a manner different from that described. The above description is intended to be exemplary and not restrictive. Therefore, it will be appreciated by those skilled in the art that modifications may be made to the described invention without departing from the scope of the aspects set forth below.

aspect

1. A container for an EUV radiation source, the container comprising:

a guide portion for guiding the fuel debris from the plasma formation region of the EUV radiation source toward the fuel debris removal device;

a wall comprising an opening, wherein at least a portion of the guide portion is disposed in the opening of the wall so as to define a gap between the guide portion and the wall; and

A gas supply system is configured to supply gas into the gap to control heat transfer between the guide portion and the wall.

2. A container according to aspect 1, wherein the gas supply system is capable of operating between a first configuration and a second configuration, wherein in the first configuration, the gas supply system is configured to supply the gas into the gap to increase heat transfer between the guide portion and the wall, and wherein, in the second configuration, the gas supply system is configured not to supply gas into the gap to reduce heat transfer between the guide portion and the wall.

3. A container according to aspect 2, wherein the gas supply system is configured to operate in the first configuration when the EUV radiation source generates EUV radiation, and wherein the gas supply system is configured to operate in the second configuration when the EUV radiation source does not generate EUV radiation.

4. A container according to any one of aspects 2 or 3, wherein the pressure of the gas in the gap when the gas supply system is in the first configuration is greater than the pressure of the gas in the gap when the gas supply system is in the second configuration.

5. A container according to aspect 4, wherein, when the gas supply system is in the first configuration, the pressure of the gas in the gap is between approximately 10 kPa and 20 kPa, and wherein, when the gas supply system is in the second configuration, the pressure of the gas in the gap is between approximately 100 Pa and 200 Pa.

6. A container according to any of the preceding aspects, wherein the gas supply system is configured to control the pressure of the gas in the gap to control heat transfer between the guide portion and the wall, and the gas supply system is configured to control the pressure of the gas in the gap based on at least one of the type of gas and the size of the gap.

7. A container according to any preceding aspect, wherein, in use, the wall is subjected to a cooling source and the guide is subjected to a heating source.

8. The container of clause 7, wherein the heating source comprises a heating element configured to heat the guide portion when the EUV radiation source does not generate EUV radiation, the heating element being a part of the guide portion.

9. A container according to aspect 7 or 8, wherein the guide portion is arranged in the container so that, in use, the guide portion is subjected to heat generated at the plasma formation region of the EUV radiation source.

10. The container according to any one of aspects 7 to 9, wherein the cooling source comprises a cooling element configured to cool the wall, the cooling element being part of the wall.

11. The container of any preceding aspect, wherein the gas comprises a thermal conductivity between about 0.02 W/mK and 0.18 W/mK at room temperature.

12. The container according to any preceding aspect, wherein the gas is selected from at least one of the following: hydrogen, nitrogen and helium.

13. A container according to any of the preceding aspects, wherein the container comprises at least one restriction element or a plurality of restriction elements for maintaining the pressure of the gas in the gap, at least some of the plurality of restriction elements being arranged in the gap and/or the wall.

14. A container according to any preceding aspect, wherein the container comprises a plurality of spacer elements for maintaining the size of the gap, the plurality of spacer elements being arranged between the guide portion and the wall.

15. A container according to any preceding aspect, wherein the container comprises a plurality of inlets for directing the gas into the gap, the plurality of inlets being arranged in the wall.

16. An EUV radiation source comprising a container according to any preceding aspect.

17. A lithography system comprising the EUV radiation source according to clause 16 and a lithography apparatus.

Claims (15)

1. A container for an EUV radiation source, the container comprising: a guide portion for guiding the fuel debris from the plasma formation region of the EUV radiation source toward the fuel debris removal device; a wall comprising an opening, wherein at least a portion of the guide portion is disposed in the opening of the wall so as to define a gap between the guide portion and the wall; and A gas supply system is configured to supply gas into the gap to control heat transfer between the guide portion and the wall. 2. The container of claim 1 , wherein the gas supply system is operable between a first configuration and a second configuration, wherein, in the first configuration, the gas supply system is configured to supply the gas into the gap to increase heat transfer between the guide portion and the wall, and wherein, in the second configuration, the gas supply system is configured not to supply the gas into the gap to reduce heat transfer between the guide portion and the wall. 3. The container of claim 2, wherein the gas supply system is configured to operate in the first configuration when the EUV radiation source generates EUV radiation, and wherein the gas supply system is configured to operate in the second configuration when the EUV radiation source does not generate EUV radiation. 4. The container according to any one of claims 2 or 3, wherein the pressure of the gas in the gap when the gas supply system is in the first configuration is greater than the pressure of the gas in the gap when the gas supply system is in the second configuration. 5. A container according to claim 4, wherein, when the gas supply system is in the first configuration, the pressure of the gas in the gap is between about 10 kPa and 20 kPa, and wherein, when the gas supply system is in the second configuration, the pressure of the gas in the gap is between about 100 Pa and 200 Pa. 6. A container according to any preceding claim, wherein the gas supply system is configured to control the pressure of the gas in the gap to control heat transfer between the guide portion and the wall, and the gas supply system is configured to control the pressure of the gas in the gap based on at least one of the type of gas and the size of the gap. 7. A container according to any preceding claim, wherein, in use, the wall is subjected to a cooling source and the guide is subjected to a heating source. 8. The container of claim 7, wherein the heating source comprises a heating element configured to heat the guide portion when the EUV radiation source does not generate EUV radiation, the heating element being a part of the guide portion. 9. The container of any preceding claim, wherein the gas comprises a thermal conductivity of between about 0.02 W/mK and 0.18 W/mK at room temperature. 10. A container according to any preceding claim, wherein the container comprises at least one restriction element or a plurality of restriction elements for maintaining the pressure of the gas in the gap, at least some of the plurality of restriction elements being arranged in the gap and/or in the wall. 11. A container according to any preceding claim, wherein the container comprises a plurality of spacer elements for maintaining the size of the gap, the plurality of spacer elements being arranged between the guide and the wall. 12. A container according to any preceding claim, wherein the container comprises a plurality of inlets for directing the gas into the gap, the plurality of inlets being arranged in the wall. 13. An EUV radiation source comprising a container according to any preceding claim. 14. A lithography system comprising the EUV radiation source according to claim 13, and a lithography apparatus. 15. A guide for use in a container, the guide being configured such that when at least a portion of the guide is disposed in an opening in a wall of the container, a gap is defined between the wall of the container and the guide.