CN114557136A

CN114557136A - Device for a radiation source

Info

Publication number: CN114557136A
Application number: CN202080072810.1A
Authority: CN
Inventors: M·里彭; P·P·A·A·布罗姆; R·德鲁伊特; M·V·格里克-吉伦; G·梅利索尔戈斯; T·J·斯考特
Original assignee: ASML Holding NV
Current assignee: ASML Holding NV
Priority date: 2019-10-16
Filing date: 2020-09-18
Publication date: 2022-05-27
Also published as: TW202130224A; WO2021073833A1; KR20220078612A

Abstract

A containment device is provided that is configured to contain waste products of a laser producing plasma radiation source. The accommodating device comprises: a first portion defining a chamber; and a second portion at least partially defining an inlet to the chamber. In use, waste product enters the chamber through the inlet. The second portion is formed of a material including a ceramic material. The containment device is particularly useful in a radiation source for a lithographic system.

Description

Device for a radiation source

Cross Reference to Related Applications

This application claims priority to EP application 19203471.8 filed on 16/10/2019, which is incorporated herein by reference in its entirety.

Technical Field

The present invention relates to a radiation source. In particular, the invention relates to an apparatus suitable for transporting and/or containing waste products of a radiation source, such as tin.

Background

A lithographic apparatus is a machine that is configured to apply a desired pattern onto a substrate. Lithographic apparatus can be used, for example, to manufacture Integrated Circuits (ICs). For example, a lithographic apparatus may project a pattern from a patterning device (e.g., a mask) onto a layer of radiation-sensitive material (resist) provided on a substrate.

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

EUV radiation may be generated using a Laser Produced Plasma (LPP) radiation source. The LPP radiation source may use a fuel such as liquid tin. After generation of EUV radiation, tin may constitute a waste product of the radiation source. The exhaust system may be used to remove waste products (such as liquid tin) from the radiation source. To facilitate such removal of the waste products, portions of the discharge system may be maintained at a temperature above the melting point of the waste products so that the waste products may flow.

However, the waste product may accumulate in one or more components of the discharge system, particularly if the components of the discharge system are not maintained above the melting point of the waste product. This may result in reduced flow and/or clogging within the exhaust system. Furthermore, tin can corrode components of the exhaust system and thus shorten their service life.

It may be desirable to overcome problems associated with waste products of the radiation source, such as tin, such as the problems described above. Accordingly, embodiments of the present invention relate to a novel apparatus suitable for transporting and containing waste products of a radiation source.

Disclosure of Invention

According to a first aspect of the present invention there is provided a containment device arranged to contain waste products of a laser producing plasma radiation source. The containment device may include a first portion. The first portion may define a chamber. The receiving means may comprise a second portion. The second portion may at least partially define an inlet to the chamber. In use, waste products may enter the chamber through the inlet. The second portion may be formed of a material including a ceramic material.

The second portion at least partially defines an inlet to the chamber, the second portion being formed of a material including a ceramic material. In particular, one or more surfaces of the second portion defining the inlet to the chamber may be formed from a material comprising a ceramic material. In some embodiments, the second portion may be formed from such a ceramic material. Alternatively, the second portion may be formed from another material, which may be coated with such a ceramic material.

The waste product of the radiation source may comprise tin.

The first portion may be referred to as a body. The second portion may be referred to as a collar. The inlet of the chamber may be defined as an opening.

A laser-produced plasma (LPP) radiation source may generate radiation by providing droplets of a liquid fuel, such as droplets of liquid tin, with energy via a laser beam. The liquid fuel may constitute a waste product of the radiation source. That is, the waste product may include liquid tin. It may be desirable to remove such waste products from the radiation source. The radiation source may be provided with an exhaust system. Any waste products within the radiation source may be discharged into the containment device via the discharge system. The containment device may also be referred to as a bucket. The containment means may be arranged to receive and store waste products. In particular, waste products may be received via an inlet of the chamber and may be stored within the chamber.

The containing means advantageously comprise a first part and a second part. In particular, the first portion (which may constitute the body of the containment device) may be formed from a first material and the second portion (which may constitute the collar of the containment device) may be formed from a second, different material. The material of the first portion and the material of the second portion may be selected to have different advantageous properties. For example, the material of the first portion may advantageously be adapted to store waste products of the radiation source. The material of the second portion may advantageously be adapted to be non-adhering and/or non-wetting with the waste products.

The ceramic material forming the second portion may be substantially non-wetting with respect to the waste products. If the waste product reaches the second portion, it may be less likely to wet the surface of the second portion. In addition, the second portion may be substantially non-adherent to the waste product. The non-stick nature of the ceramic material may facilitate removal of waste products from the surface of the second portion. Thus, even if the temperature of the second section is below the melting point of the waste product, any waste product may not remain on the surface of the second section. Advantageously, this may prevent the accumulation of waste products around the inlet of the chamber. This may prevent the formation of blockages in the discharge system of which the receiving means forms part. This is advantageous because any clogging of the exhaust system may result in a significant reduction of the throughput (e.g. of the radiation source and/or the lithographic apparatus).

In particular, previous designs of containment devices used in the exhaust system of the radiation source may not include a second portion formed of a ceramic material. These previous designs may be prone to plugging due to the accumulation of waste products. In this prior design, the waste product may wet the surfaces near the opening in the containment device. In such prior designs, waste products may adhere to surfaces near the opening in the containment device. Thus, over time, more and more waste product may be deposited near the opening in the containment device. This may reduce the efficiency of delivering waste products into such previously designed containment devices. This may eventually lead to clogging of the drainage system using such previously designed containment devices.

According to a first aspect of the invention, the new design of the containment device substantially mitigates (and may even eliminate) the risk of such clogging occurring. The new design of the containment device according to the first aspect of the invention therefore provides significant advantages over known containment devices.

Hydrogen may be provided within the radiation source. A mechanism may be provided for providing a flow of hydrogen gas within the radiation source. Providing a flow of hydrogen gas within the radiation source across the surface of the component may help prevent waste products from interacting with and/or accumulating on the surface.

Most metal-containing materials are generally not wetted by waste products under normal atmospheric conditions. The non-wetting property may be due to an oxide layer formed on the surface of such a material. However, such an oxide layer may be removed in a hydrogen-containing ambient. In particular, the oxide layer may be chemically reduced in an environment where hydrogen radicals are present. This may result in increased wetting of the waste product. Thus, preventing the accumulation of waste products on the surface of the second portion due to the presence of hydrogen gas and/or hydrogen radicals can be particularly challenging.

A particular advantage of the containment device according to the first aspect of the invention is that the ceramic material may not be wetted and generally not adhered by the waste products even in the presence of hydrogen. Thus, the second part formed of such a ceramic material provides the above-mentioned advantages even in a particularly challenging environment generated in the presence of hydrogen.

The first portion may be formed of a material including molybdenum. The first portion may be formed of a material that includes more than 90% molybdenum (e.g., more than 95% molybdenum). For example, the first portion may be formed from a material including a titanium-zirconium-molybdenum alloy. The titanium-zirconium-molybdenum alloy may include 99.4% molybdenum, 0.5% titanium, and 0.08% zirconium.

When the first portion is formed of a material comprising molybdenum (e.g., a titanium-zirconium-molybdenum alloy), the first portion is corroded negligibly or not by the waste products. For example, the first portion may be corroded negligibly or not by the liquid tin. In particular, at temperatures at which the containment device can be maintained, corrosion of the first portion is negligible or no. This is particularly advantageous with respect to known containment devices for storing waste products of the radiation source, such as liquid tin, which may be formed of stainless steel. The waste products may react with the stainless steel. Stainless steel may be corroded by waste products. This may lead to failure of such containment devices. Impurities in stainless steel, weld defects, and/or thermal stresses can exacerbate the problem. Thermal gradients can exacerbate this problem.

The TZM may be substantially free of hydrogen embrittlement. This is particularly advantageous due to the possibility of hydrogen gas and/or hydrogen radicals being present in the vicinity of the first portion.

The ceramic material may comprise boron and/or fluorine. Advantageously, it has been found that ceramic materials comprising boron or fluorine are particularly non-wetting and non-adherent to tin, even in a reducing environment in the presence of hydrogen gas and/or hydrogen radicals.

The ceramic material may include: silicon oxide; magnesium oxide; alumina; potassium oxide; boron oxide; and fluorine.

Such materials may include MACOR by Corning incorporated, Inc. of America^TMThe materials sold. Such a material may enable the second portion to achieve the significant advantages described above by implementing the first aspect of the invention. MACOR^TMMay in particular not be adhered by waste products, in particular liquid tin. MACOR^TMMay be particularly non-wetting by waste products, in particular liquid tin. Even in the presence of hydrogen, MACOR^TMAre generally non-wetting with respect to the waste product and are generally non-adherent to the waste product. In particular, the material comprises boron and fluorine.

The ceramic material may include a metal nitride. Advantageously, it has been found that metal nitrides (in particular boron nitride and aluminum nitride) are particularly non-wetting and non-adherent to tin, even in a reducing environment in the presence of hydrogen gas and/or hydrogen radicals. Such metal nitrides may be more suitable than metal oxides, for example.

The ceramic material may comprise boron nitride.

Such a material may enable the second portion to achieve the significant advantages described above by implementing the first aspect of the invention. The boron nitride may in particular not be adhered by waste products, in particular liquid tin. The boron nitride may in particular not be wetted by the waste products, in particular liquid tin. Even in the presence of hydrogen, boron nitride is generally non-wetting and generally non-adherent to waste products.

The boron nitride may be pyrolytic boron nitride.

That is, the ceramic material may include pyrolytic boron nitride. Such a material may enable the second portion to achieve the significant advantages described above by implementing the first aspect of the invention. Pyrolytic boron nitride may in particular not be adhered by waste products, in particular liquid tin. Pyrolytic boron nitride may be particularly non-wetting by waste products, particularly liquid tin. Pyrolytic boron nitride can be generally non-wetting and generally non-adherent to waste products, even in the presence of hydrogen.

The ceramic material may comprise aluminum nitride.

The ceramic material may include boron nitride and aluminum nitride. Such materials may be included as SHAPAL^TM、SHAPAL^TM-M and/or SHAPAL^TMMaterial sold by Hi-M Soft. Such a material may enable the second portion to achieve the significant advantages described above by implementing the first aspect of the invention. Boron nitride and aluminum nitride may in particular not be adhered by waste products, in particular liquid tin. Boron nitride and aluminum nitride may in particular not be wetted by waste products, in particular liquid tin. Boron nitride and aluminum nitride may be generally non-wetting and may generally be non-adherent to waste products even in the presence of hydrogen.

According to a second aspect of the present invention there is provided a laser producing plasma radiation source comprising a containment device according to the first aspect of the present invention.

According to a third aspect of the present invention, there is provided a plasma radiation source for generating laser light. The laser producing plasma radiation source may include components for use in an exhaust system of the radiation source. The assembly may define a chamber arranged to contain waste products of the radiation source. The component may be formed from a material including molybdenum.

The component may be formed from a material that includes more than 90% molybdenum (e.g., more than 95% molybdenum). For example, the component may be formed from a material including a titanium-zirconium-molybdenum alloy. The titanium-zirconium-molybdenum alloy may include 99.4% molybdenum, 0.5% titanium, and 0.08% zirconium.

The exhaust system may be used to facilitate removal of waste products of the radiation source. The LPP radiation source according to the third aspect of the present invention is advantageous in that when the component is formed from a material comprising molybdenum (such as, for example, TZM), the corrosion of the component by the waste products is negligible or no corrosion of the component by the waste products is observed. For example, the corrosion of the liquid tin to the component may be negligible or none. The LPP radiation source according to the third aspect of the invention is particularly advantageous over LPP radiation sources comprising components formed from, for example, stainless steel. For example, waste products of the radiation source may react with components formed of stainless steel. Stainless steel may be corroded by waste products. This may lead to failure of such components. Impurities in stainless steel, weld defects, thermal gradients, and/or thermal stresses can exacerbate the problem.

The TZM may be substantially free of hydrogen embrittlement. This is particularly advantageous due to the possibility of hydrogen gas and/or hydrogen radicals being present in the vicinity of the components within the radiation source.

This assembly may be referred to as a containment device. Advantageously, the waste products have negligible or no corrosion on the containment device.

According to a fourth aspect of the present invention there is provided a laser producing plasma radiation source comprising a component for use in an exhaust system of the radiation source, wherein the component comprises a ceramic material comprising boron and/or fluorine.

The component of the radiation source according to the fourth aspect of the invention comprises a ceramic material. It should be understood that this is intended to include: embodiments in which the entire component is formed of such a ceramic material, or alternatively embodiments in which the component is formed of another material, which may be coated with such a ceramic material.

The LPP radiation source according to the fourth aspect of the present invention is advantageous in that the ceramic material may be substantially non-wetted by the waste product. Advantageously, it has been found that ceramic materials comprising boron or fluorine are particularly non-wetting and non-adherent to tin, even in a reducing environment in the presence of hydrogen gas and/or hydrogen radicals. If waste products reach the component, the surface of the component may not be wetted. Furthermore, the ceramic material may not be substantially adhered by the waste product. The non-stick nature of the ceramic material may facilitate removal of waste products from the surface of the component. Advantageously, this may prevent waste products from accumulating on the assembly. This may prevent clogging of the discharge system. This is advantageous because any clogging of the exhaust system may result in a significant reduction of the throughput (e.g. of the radiation source and/or the lithographic apparatus).

The ceramic material may include: silicon oxide; magnesium oxide; alumina; potassium oxide; boron oxide; and fluorine. The exhaust system may be used to facilitate removal of waste products of the radiation source. The ceramic material may comprise MACOR, Inc. of Corning, USA^TMThe materials sold. Additionally or alternatively, the ceramic material may comprise boron nitride.

According to a fifth aspect of the present invention there is provided a laser producing plasma radiation source comprising a component for use in an exhaust system of the radiation source, wherein the component comprises a ceramic material comprising a metal nitride. The ceramic material may comprise boron nitride and/or aluminum nitride.

The component of the radiation source according to the fifth aspect of the invention comprises a ceramic material. It should be understood that this is intended to include: embodiments in which the entire component is formed of such a ceramic material, or alternatively embodiments in which the component is formed of another material, which may be coated with such a ceramic material.

The exhaust system may be used to facilitate removal of waste products of the radiation source. The LPP radiation source according to the fifth aspect of the present invention is advantageous in that the ceramic material may be substantially non-wetted by the waste products. Advantageously, it has been found that metal nitrides (in particular boron nitride and aluminum nitride) are particularly non-wetting and non-adherent to tin, even in a reducing environment in the presence of hydrogen gas and/or hydrogen radicals. Such metal nitrides may be more suitable than metal oxides, for example. If waste products reach the component, the surface of the component may not be wetted. Furthermore, the ceramic material may not be substantially adhered by the waste product. The non-stick nature of the ceramic material may facilitate removal of waste products from the surface of the component. Advantageously, this may prevent waste products from accumulating on the assembly. This may prevent clogging of the discharge system. This is advantageous because any clogging of the exhaust system may result in a significant reduction of the throughput (e.g. of the radiation source and/or the lithographic apparatus).

The ceramic material may comprise boron nitride and/or aluminum nitride. The boron nitride may include pyrolytic boron nitride.

The ceramic material may include as SHAPAL^TM、SHAPAL^TM-M and/or SHAPAL^TMMaterial sold by Hi-M Soft.

The radiation source according to the second, third, fourth or fifth aspect of the invention may further comprise means for providing hydrogen. Hydrogen may be provided to one or more surfaces within the radiation source.

Providing a flow of hydrogen gas across one or more surfaces within the radiation source may help prevent waste products of the radiation source from interacting with and/or accumulating on the surfaces.

Most metal-containing materials can be generally non-wetted by waste products under normal atmospheric conditions. This non-wetting property may be due to an oxide layer formed on the surface of such material. However, such an oxide layer may be removed in a hydrogen-containing ambient. In particular, the oxide layer may be chemically reduced in an environment where hydrogen radicals are present. This may result in increased wetting of the waste product. Thus, preventing the accumulation of waste products on the surface of the second portion due to the presence of hydrogen gas and/or hydrogen radicals can be particularly challenging.

One particular advantage of forming the assembly from the materials given in the second, third, fourth or fifth aspect of the invention is that: even in the presence of hydrogen, these materials may not be generally wetted and generally adhered by the waste products and/or may generally be resistant to corrosion by the waste products (such as tin). Thus, the LPP radiation source according to the second, third, fourth or fifth aspect of the invention provides significant advantages even in particularly challenging environments where hydrogen is generated in the presence of hydrogen.

The assembly of radiation sources according to the third, fourth or fifth aspects of the invention may at least partially define an entrance to the chamber. The chamber may be arranged to contain waste products of the radiation source and the assembly may correspond to the "second portion" according to the first aspect of the invention. This assembly may be referred to as a collar. The collar may be substantially non-wetted by waste product. If waste products reach the collar, the surface of the collar may not be wetted. Additionally, the collar may be substantially free from sticking by waste products. The non-stick nature of the ceramic material may facilitate removal of waste products from the surface of the collar. Advantageously, this may prevent waste product from accumulating on the collar. This may prevent clogging of the discharge system. This is advantageous because any clogging of the exhaust system may result in a significant reduction of the throughput (e.g. of the radiation source and/or the lithographic apparatus).

The assembly of radiation sources according to the third, fourth or fifth aspects of the invention may comprise a tube. The conduit may be configured to convey waste products of the radiation source.

The conduit may be substantially non-wetting to the waste product. If waste products are present on the tubing, it may be less likely to wet the surface of the tubing. Further, the conduit may be substantially free of adhering waste products. The non-stick nature of the ceramic material may facilitate removal of waste products from the surface of the pipe. Advantageously, this may prevent waste products from accumulating on the pipeline. This may prevent clogging of the discharge system. This is advantageous because any clogging of the exhaust system may result in a significant reduction of the throughput (e.g. of the radiation source and/or the lithographic apparatus).

The waste product of the radiation source according to the second, third, fourth or fifth aspect of the invention may comprise tin.

Drawings

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

FIG. 1 depicts a schematic representation of a side view of a lithographic system including a lithographic apparatus and a radiation source;

FIG. 2 depicts a three-dimensional perspective view of a containment device for use in a radiation source;

FIG. 3 depicts a schematic representation of a side view of the containment device depicted in FIG. 2; and

figure 4 depicts a process by which the containment device of figures 2 and 3 may be inserted into the exhaust system of a radiation source.

Detailed Description

FIG. 1 depicts a lithographic system including a radiation source SO and a lithographic apparatus LA. The radiation source SO is configured to generate an Extreme Ultraviolet (EUV) radiation beam B and to provide the EUV radiation beam B to the lithographic apparatus LA. The lithographic apparatus LA comprises an illumination system IL, a support structure (e.g. a mask table) 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 facet field mirror device 10 and a facet pupil mirror device 11. The faceted field mirror device 10 and the faceted pupil mirror device 11 together provide a beam B of EUV radiation having a desired cross-sectional shape and a desired intensity distribution. The illumination system IL may comprise other mirrors or devices in addition to or instead of the facet field mirror device 10 and the facet pupil mirror device 11.

After being so conditioned, the EUV radiation beam B interacts with the patterning device MA. Due to this interaction, a patterned beam B' of EUV radiation is generated. The projection system PS is configured to project a patterned beam B' of EUV radiation onto a substrate W. To this end, the projection system PS may comprise a plurality of

mirrors

13, 14 configured to project the patterned beam B' of EUV radiation onto a substrate W held by the substrate table WT. The projection system PS may apply a reduction factor to the patterned EUV radiation beam B' to form an image having features smaller than corresponding features on the patterning device MA. For example, a reduction factor of 4 or 8 may be applied. Although the projection system PS is shown in fig. 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).

A relative vacuum, i.e., a small amount of gas at a pressure much lower than atmospheric pressure, may be provided in the radiation source SO, the illumination system IL and/or the projection system PS.

For example, the radiation source SO shown in FIG. 1 is of the type that may be referred to as a Laser Produced Plasma (LPP) source. May for example comprise carbon dioxide (CO)₂) The laser system 1 of the laser is arranged to deposit energy into a fuel, such as tin (Sn) provided from, for example, a fuel emitter 3, via a laser beam 2. 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 comprise a nozzle configured to direct tin (e.g. in the form of droplets) along a trajectory towards the plasma formation region 4. The laser beam 2 is incident on the tin at the plasma formation zone 4. Deposition of laser energy into tin generates a tin plasma 7 at the plasma formation region 4. During deexcitation and recombination of electrons with ions of the plasma, radiation comprising EUV radiation is emitted from the plasma 7.

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 directing mirrors and/or a beam expander and/or other optics. The laser system 1, the radiation source SO and the beam delivery system may together be considered a radiation system.

EUV radiation from the plasma is collected and focused by collector 5. The collector 5 comprises, 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 ellipsoidal configuration with two foci. As described below, a first one of the foci may be at the plasma formation region 4, and a second one of the foci may be at the intermediate focus 6.

The radiation reflected by the collector 5 forms an 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 a closed structure 9 of the radiation source SO.

The process of converting the tin droplets into the tin plasma 7 is a high energy process. Any tin that is not converted into a tin plasma 7 as a result of interaction with the laser beam 2 can be ejected from the plasma formation region 4. The tin that is not converted into the tin plasma 7 may reach the inner walls of the enclosing structure 9 of the radiation source SO and/or other components within the radiation source SO. The tin plasma 7 may also diffuse from the plasma-forming region 4 (e.g., as a result of interaction with the laser beam 2). When the electrons and ions of the tin plasma 7 recombine (thereby generating radiation comprising EUV radiation), tin atoms are formed. These tin atoms may reach the inner walls of the enclosing structure 9 of the radiation source SO and/or other components within the radiation source SO.

As mentioned above, small amounts of gas at a pressure far below atmospheric pressure may be provided in the radiation source SO. Hydrogen may be provided within the radiation source SO. A mechanism may be provided for providing a flow of hydrogen within the radiation source SO. Providing a flow of hydrogen across the surface of the component within the radiation source SO may help prevent tin from interacting with and/or accumulating on the surface.

The radiation source SO may be provided with an exhaust system. Any tin within the enclosing structure 9 may drain into the containment device 20 via the drainage system. The containment device 20 may also be referred to as a bucket. In particular, the surface inside the closing structure 9 may be configured to facilitate the discharge of tin into the containing means 20. The holding device 20 may form part of the exhaust system of the radiation source SO. The conduit 30 may form part of the exhaust system of the radiation source SO. The conduit 30 can be used to deliver tin to the containment device 20. Tin can be discharged from inside the enclosure 9 through the duct 30 into the containing means 20. The exhaust system may comprise one or more pipes.

It may be desirable for the tin that has been discharged into containment device 20 to be in liquid form. This may be desirable because the liquid tin may collect at one end of containment device 20 (as determined by gravity) after being delivered to containment device 20. The housing means 20 may be provided with a heating device. The heating device may heat the containment device 20 to a suitable operating temperature. A suitable operating temperature for containment device 20 may be above the melting point of tin. It will be appreciated that the temperature of the radiation source SO (particularly within the enclosure 9) may be significantly higher than the temperature at which the containment device 20 operates.

In some embodiments, containment device 20 may be located in and/or considered part of radiation source SO. In other embodiments, containment device 20 may be at least partially external to radiation source SO and/or considered to at least partially not form part of radiation source SO. In embodiments where the containment device 20 is located outside the vessel of the radiation source SO, there may be some differences from embodiments where the containment device is located inside the vessel of the radiation source SO, but the overall concept may remain the same.

Although fig. 1 depicts the radiation source SO as a Laser Producing Plasma (LPP) source, any suitable source, such as a Discharge Producing Plasma (DPP) source (it being understood that it may also produce waste products, such as tin), may be used to generate EUV radiation.

Fig. 2 depicts a three-dimensional perspective view of containment device 20 according to an embodiment of the present invention.

The accommodating device 20 includes: a main body 21; and a collar 25. The body 21 may be referred to as a first portion. Collar 25 may be referred to as a second portion.

The housing device 20 further includes: a plurality of connection points 22; a plurality of movement limiters 23; an opening 24; a recess 26; and a tray 27 with a splash cover 28.

The body 21 is substantially cubical. Both edges of the body 21 are chamfered, resulting in

chamfered edges

21b, 21 c. It should be understood that in other embodiments of containment device 20, body 21 may have a different shape. The body 21 of the containment device 20 may be formed from a plurality of individual components. This may be advantageous for manufacturing considerations. The body 21 is generally hollow. That is, the body 21 generally defines a cavity. The cavity may be referred to as a reservoir. The opening 24 is an opening in the top surface 21a of the body 21. It should be understood that the top surface 21a of the body 21 is intended to refer to the surface of the body 21 that faces in use in a direction generally opposite to the direction in which gravity acts. That is, in use, the top surface 21a may be described as generally above the other surfaces of the body 21. The opening 24 may be described as an aperture or a cutout. Opening 24 provides fluid communication between the cavity within body 21 and the environment in which containment device 20 is located.

Multiple attachment points 22 may allow containment device 20 to be attached to the external frame of the exhaust system. Alternatively, multiple connection points may allow containment device 20 to be connected to any other component. It should be understood that each connection point 22 may comprise part of any standard mechanism for securing one component to another, as is well known in the art. The plurality of movement limiters 23 may prevent undesired movement of the accommodating device 20. In particular, when containment device 20 is used as part of a venting system, plurality of movement limiters 23 may prevent undesired movement of containment device 20. A plurality of movement limiters 23 project from the outer dimension of the body 21.

Collar 25 is a separate component from the component forming part of body 21. The collar 25 is in contact with the top surface 21a of the body 21. Collar 25 extends from top surface 21 a. The collar 25 extends from the top surface 21a in a direction substantially perpendicular to the main plane of the top surface 21 a. It should be understood that in alternative embodiments, collar 25 may extend in a different direction. A collar 25 extends outwardly from the body 21. That is, the collar 25 extends from the top surface 21a in a direction opposite to the direction in which the cavity of the body 21 is provided.

The collar 25 is substantially U-shaped in a cross-section perpendicular to the direction in which the collar 25 extends from the top surface 21a and in the portion of the collar extending above the top surface 21 a. The portion of the collar 25 that extends above the top surface 21a of the body 21 may be referred to as an upper portion 25e of the collar 25.

The collar 25 has a generally rectangular shape in a cross-section perpendicular to the direction in which the collar 25 extends from the top surface 21a and in portions of the collar that do not normally extend above the top surface 21 a. The portion of the collar 25 that does not normally extend above the top surface 21a of the body 21 may be referred to as the lower portion 25f of the collar 25. The lower portion 25f comprises material only at the periphery of the lower portion 25f, such that the lower portion 25f comprises a central aperture. The lower portion 25f forms a closed shape (which extends partially into the body 21 so as to define the opening 24).

Since the collar 25 is substantially U-shaped in the upper portion 25e of the collar 25, the collar 25 defines a recess 25a between two substantially mutually perpendicularly extending

portions

25b, 25 c. The recess 25a may be described as an open portion of the collar 25. A collar 25 is provided partially around the opening 24. In particular, collar 25 delimits the edge of opening 24. Fluid communication between the cavity within the body 21 and the environment in which the containment device 21 is disposed is provided via a conduit defined by an opening 24 and a collar 25.

The receiving means 20 is oriented at an angle to the horizontal, i.e. to the ground (which may be in the y-direction). This is because the radiation source SO is also angled with respect to the horizontal plane. In an alternative embodiment, containment device 20 may be oriented horizontally (i.e., the bottom of containment device 20 may be oriented parallel to the y-direction (i.e., the ground)).

The recess 26 is defined by a portion of the top surface 21a adjacent the notch 25a of the collar 25. In particular, the recess 26 is defined by a portion of the top surface 21a that extends from the top surface 21a in the same direction as the cavity of the body 21 is arranged. The recess 26 may protrude only slightly from the top surface 21 a. The edge of the recess 26 is close to the collar 25. In particular, the

extension portions

25b, 25c of the collar 25 partially surround a portion of the recess 26 such that the base of the recess 25a is defined by said portion of the recess 26.

The recess 26 extends from the collar 25 to the edge of the top surface 21a of the body 21. The tray 27 comprises a generally cuboidal component having an open face. The tray 27 may be substantially smaller than the body 21 of the containment device 20. The tray 27 is provided on the side surface 21d of the main body 21. The tray 27 is disposed such that the opening face of the tray 27 is close to the edge of the top surface 21a of the main body 21 to which the recess 26 extends. The splash cover 28 comprises a generally rectangular assembly. The splash cover 28 can be described as a thin sheet. A splash cover 28 may be affixed to the tray 27. The splashboard cover 28 may be attached to a face of the tray 27 opposite to a face of the tray provided on the side surface 21d of the main body 21. The splash cover 28 extends from the tray 27 so as to at least partially cover the edge of the top surface 21a of the body 21 to which the recess 26 extends.

The body 21 may be formed of a material including molybdenum. Advantageously, molybdenum has a high resistance to corrosion by tin, which makes materials comprising molybdenum particularly suitable for forming body 21. Body 21 may also include one or more additional materials to increase the strength of body 21. The body 21 may be formed of a material including titanium. The body 21 may be formed of a material including zirconium. The body 21 may be formed from a material including a titanium-zirconium-molybdenum alloy (referred to as TZM). The titanium-zirconium-molybdenum alloy may include 99.4% molybdenum, 0.5% titanium, and 0.08% zirconium. This can be formed by adding TiC and ZrC to molybdenum in order to improve the strength properties of the material (relative to pure molybdenum).

Collar 25 may be formed from a material including a ceramic material.

Collar 25 may be formed from a material comprising any combination of: silicon oxide; magnesium oxide; alumina; potassium oxide; boron oxide; and/or fluorine. Specifically, collar 25 may be formed from a material that includes: silicon oxide; magnesium oxide; alumina; potassium oxide; boron oxide; and fluorine. The material may include MACOR by Corning incorporated, USA^TMThe materials sold.

The collar 25 may be formed of a material including Boron Nitride (BN). The collar 25 may be formed of a material including aluminum nitride (AlN). Collar 25 may be formed from materials including boron nitride and aluminum nitride. The material may be included as SHAPAL^TM/SHAPAL^TM-M and/or SHAPAL^TMMaterial sold by Hi-M Soft. Collar 25 may be formed from a material including pyrolytic boron nitride, which may be referred to as PBN.

Several oxides are given herein. It is to be understood that the word "oxide" as used in the compounds may refer to any suitable oxide (such as a dioxide, a trioxide, etc.). In particular, silicon oxide may refer to a silicon atom (SiO) bonded to two oxygen atoms₂) Which may be referred to as silicon dioxide. Magnesium oxide may refer to magnesium atoms (MgO) bonded to oxygen atoms, which may be referred to as magnesium oxide. Alumina may refer to two aluminum atoms (Al) bonded to three oxygen atoms₂O₃) Which may be referred to as alumina. Potassium oxide may refer to two potassium atoms (K2O) bonded to one oxygen atom. Boron oxide may refer to two boron atoms (B) bonded to three oxygen atoms₂O₃)。

Fig. 3 depicts a schematic representation of a side view of the containment device 20.

In use, the containment device 20 may be arranged to interface with a conduit of a drainage system (e.g., conduit 30 shown in fig. 1). Fig. 3 shows the profile of a section of the pipe 30 interfacing with the housing device 20. One end of conduit 30 is proximate opening 24 of containment device 20. In particular, the end of the conduit 30 is at least partially surrounded by a collar 25 (in fig. 3, the dashed line of the conduit 30 shows a cross section of the conduit partially surrounded by the collar 25). The end of the conduit 30 is at least partially surrounded by the upper portion 25e of the collar 25. The upper portion 25e of the collar 25 may be described as a partial cross-section of a pipe. The lower portion 25f of the collar 25 can be described as the full cross-section of the conduit (because, unlike the upper portion 25e, the lower portion 25f does not include a recess and the lower portion 25f is therefore a closed shape). Collar 25 may interface with drain system conduit 30. When conduit 30 interfaces with collar 25, this may be described as the formation of a composite conduit, including conduit 30, upper portion 25e of collar 25e, and lower portion 25f of collar 25. Collar 25 also includes a flange portion 25 d. The flange portion 25d is disposed around the edge of the collar 25 such that when the pipe 30 is interfaced with the collar 25, the flange portion 25d is proximate to the pipe 30. The flange portion 25d increases the extent to which the upper portion 25e of the collar 25 partially surrounds the pipe 30.

As mentioned above, tin can be discharged from the interior of the enclosing structure 9 of the radiation source SO into the receiving device 20 through one or more ducts, for example the duct 30. The flow 31 of tin through the tube 30 is shown in fig. 3. The tin stream 31 exits the end of the tube 30. The tin flow 31 then passes through the opening 24. The tin stream 31 then enters the cavity of the body 21 of the containment device 20. The containment device 20 can thus receive and collect tin from the exhaust system of the radiation source SO.

Known containers for storing liquid tin are made of stainless steel. The liquid tin may react with the stainless steel. Stainless steel may be corroded by liquid tin. For example, in known containment devices for storing liquid tin, the containment device in operation each year may remove approximately 100 μm of stainless steel from the surface of the stainless steel. This may lead to failure of such a containment device. Impurities in stainless steel may exacerbate the problem. Weld defects (from the formation of stainless steel containment devices) can exacerbate the problem. Thermal stresses (from the formation of stainless steel containment devices) can exacerbate the problem. Temperature gradients within the containment device may also significantly exacerbate the problem.

As described above, according to embodiments of the present invention, the body 21 may be formed of a material including molybdenum (e.g., TZM as described above). Advantageously, the body 21 (formed of a material comprising molybdenum) is corroded negligibly or not by liquid tin. In particular, at the temperature at which containment device 20 is maintained, there is negligible or no corrosion of body 21.

The TZM may have a thermal conductivity that is about 9 times greater than that of stainless steel. Thus, advantageously, the heating and cooling times of the body 21 (formed of a material including TZM) may be shorter than those of a body of a containment device formed of stainless steel. This may lead to yield advantages (e.g. yield of the radiation source SO and the lithographic apparatus LA). It is also advantageously possible to use a simpler design of the heating device than is required for a stainless steel receiving device. Such a modified design of the heating device may comprise one or more heating elements separate from the receiving means 20. Such a modified design of the heating device may comprise one or more heating elements which do not need to be removed from the radiation source SO when the cavity of the receiving means 20 is normally filled with tin.

The TZM may have a coefficient of thermal expansion that is about 3 times lower than that of stainless steel. Thus, advantageously, the thermal stresses within the body 21 (formed of a material comprising TZM) may be lower than the thermal stresses within the body of a containment device formed of stainless steel. This may advantageously make the design of the formed body 21 simpler (compared to the body of a stainless steel containment device).

As mentioned above, when the containment device 20 is used as part of the exhaust system of the radiation source SO, the tin stream 31 may exit the end of the tube 30. When the containment device 20 is in use, the end of the conduit 30 is at least partially surrounded by the collar 25 (in particular, by the upper portion 25e of the collar 25). The collar 25 may interface with the drain system conduit 30 to form a composite conduit. Advantageously, this allows to efficiently transport the tin to the containing means 20. In particular, this may result in tin being effectively transported into the cavity of the body 21 of the receiving device 20 through the opening 24.

The tin stream 31 may typically comprise liquid tin. After leaving the duct 30, the tin can reach the collar 25. After entering the cavity of the containment device 20, tin may splash back from the surface of the cavity toward the opening 24. The container 20 may be heated. In particular, the heating device may heat the body 21 above the melting point of tin so that the tin within the cavity of the body 21 is in a liquid state. However, the temperature of the collar 25 may be below the melting point of tin. This may be due to the thermal properties of the collar 25 and/or the proximity of the collar 25 to the heating elements of the heating device. For example, collar 25 may be formed from a material having a relatively low thermal conductivity (e.g., a material having a thermal conductivity that is lower than the thermal conductivity of the material forming body 21 of containment device 20). Furthermore, there is a contact resistance between the collar 25 and the body 21 of the containment device 20. Thus, while the body 21 of the holder 20 may be maintained at a temperature of about 250 ℃, the temperature of the collar 25 may be below the melting point of tin (232 ℃). Even in the case where it is intended to heat the receptacle 20 so that all parts of the receptacle 20 are above the melting point of tin, in practice the temperature of the collar 25 may be below the melting point of tin.

As described above, collar 25 may be formed to include a MACOR in accordance with embodiments of the present invention^TMIs formed of the ceramic material of (1). MACOR^TMIs substantially non-wetting to the liquid tin. If the tin reaches the collar 25 (by MACOR)^TMFormed), it may be less likely to wet the surface of the collar 25. Furthermore, MACOR^TMSubstantially not adhered by the liquid tin. MACOR^TMMay facilitate removal of tin from the surface of collar 25. Thus, even though the temperature of collar 25 may be below the melting point of tin, it is unlikely that any tin will remain on the surface of collar 25. Advantageously, this may prevent tin from accumulating around the opening 24. This may prevent clogging of the drainage system. This is advantageous because any clogging of the exhaust system may result in a significant reduction of the throughput (e.g. of the radiation source SO and the lithographic apparatus LA).

In particular, previous designs of containment devices used in the discharge system of the radiation source do not include a containment device made of ceramic material (e.g. MACOR)^TM) A formed collar (e.g., collar 25). These previous designs are prone to clogging due to tin build-up. In this previous design, the tin may wet the surface near the opening of the containment device. In this prior design, tin may stick to surfaces near the opening in the containment device. Thus, over time, more and more tin may be deposited near the opening in the containment device. This reduces the efficiency of tin delivery into such previously designed containment devices. This ultimately leads to blockage of the drainage system using this previously designed containment device.

The new design of containment device 20, according to an embodiment of the present invention, substantially mitigates (and may even eliminate) the risk of such clogging occurring. Thus, the new design of the containment device 20 according to embodiments of the present invention provides significant advantages over known containment devices.

As mentioned above, the radiation source SO may include a mechanism for providing hydrogen to the surface of the component within the radiation source SO. This hydrogen can be transported in the form of hydrogen gas. The high energy radiation within the radiation source SO may generate hydrogen radicals from hydrogen gas. Hydrogen gas and/or hydrogen radicals may diffuse through the exhaust system of the radiation source SO. Thus, hydrogen gas and/or hydrogen radicals may be present in the vicinity of containment device 20.

Most metal-containing materials are generally not wetted by liquid tin under normal atmospheric conditions. This non-wetting property may be due to an oxide layer formed on the surface of such material. However, such an oxide layer may be removed in a hydrogen-containing ambient. In particular, the oxide layer may be chemically reduced in an environment where hydrogen radicals are present. This may lead to increased wetting of the tin. Thus, preventing tin from accumulating on the surface of collar 25 due to the presence of hydrogen gas and/or hydrogen radicals may be particularly challenging.

One particular advantage of containment device 20 according to embodiments of the present invention is that the MACOR^TMEven in the presence of hydrogen, is generally not wetted by tin and is generally not adhered by tin. Thus, even in particularly challenging environments generated in the presence of hydrogen, by including MACOR^TMThe collar 25 formed of the material of (a) provides the advantages described above.

It is to be understood that, as described above, the routing may be performed by using a routing including MACOR^TMThe advantages achieved by the collar 25 formed of any other given material may be achieved by using a collar 25 formed of any other given material. In particular, the same or similar advantages may be achieved by using a collar 25 formed from a material comprising: boron nitride; boron nitride and aluminum nitride (which may be used as SHAPAL)^TM、SHAPAL^TM-M and/or SHAPAL^TMSold by Hi-M soft); or pyrolytic boron nitride.

Another advantage of the containment device 20 according to embodiments of the present invention is that the TZM (from which the body 21 may be formed, as described above) is substantially impervious to hydrogen embrittlement. This is particularly advantageous due to the possibility of hydrogen gas and/or hydrogen radicals being present in the vicinity of the body 21. Known designs of containment devices may be formed from stainless steel, which is susceptible to corrosion by tin due to corrosion by iron (the major constituent of stainless steel) by tin. Accordingly, the containment device 20 according to embodiments of the present invention is particularly advantageous over known containment device designs.

The containment device 20 may be a replaceable component of the exhaust system of the radiation source SO. The containment device 20 may be inserted into an exhaust system. Containment device 20 may be removed from the exhaust system. In particular, when the cavity of the body 21 contains a certain quantity of tin, the containing device 20 can be extracted from the draining system. A new containment device (which may be, for example, identical to containment device 20) may then be inserted into the exhaust system.

The containment device 20 may be reusable. When the cavity of body 21 contains a certain amount of tin, containment device 20 may be removed from the drainage system. The tin can be substantially removed from the containment device 20. The tin may be in a liquid state. This facilitates removal of the tin from the containment device 20. Containment device 20 may then be reinserted into the drainage system.

Fig. 4a and 4b depict the insertion of the containment device 20 into the exhaust system of the radiation source SO. Fig. 4a shows the relative position of the conduit 30 and the containment device 20 before the containment device 20 is inserted into the exhaust system. Fig. 4b shows the relative positions of the conduit 30 and the containment device 20 once the containment device 20 is inserted into the drainage system (this is also shown in fig. 3). In fig. 4a and 4b, the duct 30 and the accommodation device 20 are shown in the context of the same fixed background grid.

When the containment device 20 is inserted into the exhaust system, the conduit 30 of the exhaust system may be held stationary relative to the radiation source SO. To insert receptacle 20 into the drainage system, receptacle 20 may be moved in insertion direction 32.

Advantageously, the U-shaped cross-section of the upper portion 25e of the collar 25 allows the receptacle 20 to be inserted into a drainage system such that the collar 25 at least partially surrounds the end of the pipe 30, thereby forming a composite pipe. In particular, the notch 25a provides a space through which the end of the conduit 30 may pass when the receptacle 20 is inserted into a drainage system. Thus, the recess 25a and the flange portion 25d (see fig. 2) provide a mechanism by which advantageous coupling between the accommodation device 20 and the pipe 30 can be achieved.

The tin may reach onto the top surface 21a of the body 21. The drainage system may be configured such that any tin that reaches the top surface 21a may generally reach the portion of the top surface 21a that constitutes the recess 26. The notches 25a and recesses 26 of the collar 25 may be arranged such that any tin that diffuses through the notches 25a (e.g., tin that splashes out of the opening 24 from the cavity of the body 21, directly from the conduit 30 onto the collar 25) will be in the recesses 26.

As described above and shown in fig. 3, 4a and 4b, containment device 20 may be oriented at an angle relative to horizontal (i.e., relative to the ground). The TZM (from which the body 21 may be formed, as described above) may not be wetted by tin. The TZM may not be adhered by tin. Tin (usually in a liquid state) located on the recess 26 may diffuse toward the edge of the top surface 21a under the force of gravity, and the tray 27 is disposed near the top surface 21 a. This diffusion of tin may be advantageously promoted by the non-wetting and non-wetting properties of the TZM. One or more edges of the recess may guide the trajectory of the tin so that the tin diffuses towards the tray 27. Tin may enter the tray 27. The splash cover 28 may facilitate the reception and/or retention of tin in the tray 27.

Advantageously, the recess 26, tray 27 and splash cover 28 can prevent the tin stream 31 from contaminating the drain system or other components. The recess 26, tray 27 and splash cover 28 can collect tin that exits from the conduit 30. The recess 26, tray 27 and splash cover 28 can collect tin that reaches the receptacle 20 when the receptacle 20 is inserted into or removed from the drain system.

Although specific reference may be made in this text to the use of lithographic apparatus in the manufacture of ICs, 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 reference may be made in this text to embodiments of the invention in the context of lithographic apparatus, embodiments of the invention may be used in other apparatus. Embodiments of the invention may form part of a mask inspection apparatus, a metrology apparatus, or any apparatus that measures or processes an object such as a wafer (or other substrate) or a mask (or other patterning device). These devices are commonly referred to as lithographic tools. Such a lithography tool may use vacuum conditions or ambient (non-vacuum) conditions.

Embodiments of the invention may be implemented in hardware, firmware, software, or any combination thereof, as the context allows. Embodiments of the invention may also be implemented as instructions stored on a machine-readable medium, which may be read and executed by one or more processors. A machine-readable medium may include any mechanism for storing or transmitting information in a form readable by a machine (e.g., a computing device). For example, a machine-readable medium may include Read Only Memory (ROM); random Access Memory (RAM); a magnetic storage medium; an optical storage medium; a flash memory device; electrical, optical, acoustical or other form of propagated signals (e.g., carrier waves, infrared signals, digital signals, etc.), and others. Further, firmware, software, routines, instructions may be described herein as performing certain actions. However, it should be understood that such descriptions are merely for convenience and that such actions in fact are generated by a computing device, processor, controller, or other device executing firmware, software, routines, instructions, etc. and in so doing may cause an actuator or other device to interact with the physical world.

While specific embodiments of the invention have been described above, it will be appreciated that the invention may be practiced otherwise than as described. The above description is intended to be illustrative and not restrictive. It will therefore be apparent to those skilled in the art that modifications may be made to the invention as described without departing from the scope of the claims set out below.

Claims

1. A containment device arranged to contain waste products of a laser producing plasma radiation source, comprising:

a first portion defining a chamber; and

a second portion at least partially defining an inlet to the chamber;

wherein, in use, the waste product enters the chamber through the inlet, and wherein the second portion is formed from a material comprising a ceramic material.

2. The containment device of claim 1, wherein the first portion is formed from a material comprising molybdenum.

3. The containment device of claim 1 or 2, wherein the ceramic material comprises boron and/or fluorine.

4. The containment device of any one of claims 1 to 3 wherein the ceramic material comprises:

silicon oxide;

magnesium oxide;

alumina;

potassium oxide;

boron oxide; and

fluorine.

5. The containment device of any one of claims 1 to 3 wherein the ceramic material comprises a metal nitride.

6. The containment device of claim 5 wherein said ceramic material comprises boron nitride.

7. The containment device of claim 5, wherein the ceramic material comprises aluminum nitride.

8. A laser producing plasma radiation source comprising a containment device according to any preceding claim.

9. A laser generating plasma radiation source comprising a component for use in an exhaust system of the radiation source, wherein the component defines a chamber arranged to contain waste products of the radiation source, and wherein the component is formed from a material comprising molybdenum.

10. A laser generating plasma radiation source comprising a component for use in an exhaust system of the radiation source, wherein the component comprises a ceramic material comprising boron and/or fluorine.

11. A laser producing plasma radiation source comprising a component for use in an exhaust system of the radiation source, wherein the component comprises a ceramic material comprising a metal nitride.

12. The laser generating plasma radiation source of claim 10, wherein the ceramic material comprises:

silicon oxide;

magnesium oxide;

alumina;

potassium oxide;

boron oxide; and

fluorine.

13. The laser-generating plasma radiation source of claim 10 or 11, wherein the component comprises a ceramic material comprising boron nitride.

14. The laser-generating plasma radiation source of claim 10, 11, or 13, wherein the component comprises a ceramic material comprising aluminum nitride.

15. The radiation source of any one of claims 8 to 14, wherein the radiation source further comprises a mechanism for providing hydrogen to one or more surfaces within the radiation source.

16. A radiation source according to any one of claims 10 to 14, wherein the assembly at least partially defines an inlet to a chamber arranged to receive waste products of the radiation source.

17. The radiation source of any one of claims 10 to 14, wherein the assembly is a tube configured to convey a waste product of the radiation source.