CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Application No. 63/078,410, filed September 15, 2020, titled PRESSURE VESSEL HAVING PRESSURE BEARING SHELL, which is incorporated herein in its entirety by reference.

TECHNICAL FIELD

[0002] The disclosed subject matter relates to a pressure vessel having a pressure bearing shell and being configured to retain a fluid.

BACKGROUND

[0003] Extreme ultraviolet (EUV) light, for example, electromagnetic radiation having wavelengths of 100 nanometers (nm) or less (also sometimes referred to as soft x-rays), and including light at a wavelength of, for example, 20 nm or less, between 5 and 20 nm, or between 13 and 14 nm, can be used in photolithography processes to produce extremely small features in substrates, for example, silicon wafers, by initiating polymerization in a resist layer. Methods for generating EUV light include, but are not limited to, altering the physical state of a source material to a plasma state. The source material includes a compound or an element, for example, xenon, lithium, or tin, with an emission line in the EUV range. In one such method, often termed laser produced plasma (“LPP”), the required plasma is produced by irradiating a source material, for example, in the form of a droplet, stream, or cluster of source material, with an amplified light beam that can be referred to as a drive laser. For this process, the plasma is typically produced in a sealed vessel, for example, a vacuum chamber, and monitored using various types of metrology equipment. The source material, such as xenon, lithium, or tin, which emit in the EUV range when in the plasma state, are commonly referred to as target material since they are targeted and irradiated by the drive laser.

SUMMARY

[0004] In some general aspects, a fluid supply apparatus is configured to supply target material to a target location in a chamber of an extreme ultraviolet light source. The fluid supply apparatus includes: a priming system; a reservoir system; a nozzle supply system; and a pressure vessel within one or more of the priming system, the reservoir system, and the nozzle supply system. The priming system is configured to receive a solid matter that includes the target material and to produce a fluid target material from the solid matter. The reservoir system includes one or more fluid reservoirs in fluid communication with the priming system and configured to store the fluid target material. The nozzle supply system is in fluid communication with the reservoir system. The pressure vessel is configured to retain fluid target material. The pressure vessel includes: a liner defining a liner cavity that retains the fluid target material under pressure, and a pressure bearing shell defining a shell cavity in which the liner is fixed. The liner and pressure bearing shell form a pseudo-monolithic shape in which any gap at the interface between the liner and pressure bearing shell is small enough to prevent entry of foreign materials.

[0005] Implementations can include one or more of the following features. For example, the liner and the pressure bearing shell can be configured such that the shell exerts a compressive stress on the liner.

[0006] The interface between the liner and the pressure bearing shell can be at least partly conical in shape. The interface between the liner and the pressure bearing shell can be at least partly cylindrical in shape.

[0007] The liner can include a tube section that extends through at least one opening of the pressure bearing shell, the tube section defining an internal passageway through which the fluid target material flows.

[0008] The nozzle supply system can include a nozzle device including a capillary through which the fluid target material is flowed, the capillary being in fluid communication with the liner cavity of the pressure vessel.

[0009] The liner and the pressure bearing shell can be sealed at an end and the liner can be pressured to a pressure greater than 25 megapascals (MPa), greater than 55 MPa, greater than 80 MPa, or greater than 100 MPa.

[0010] The fluid target material can be tin or an alloy of tin. The liner can be made of molybdenum, and the pressure bearing shell can be made of a material having a coefficient of thermal expansion that matches a coefficient of thermal expansion of the molybdenum. The pressure bearing shell can be made of an alloy of iron.

[0011] In other general aspects, a pressure vessel is configured to retain a fluid. The pressure vessel includes: a liner made of a material that is compatible with the fluid; and a pressure bearing shell defining a shell cavity in which the liner is fixed. The liner defines a liner cavity that retains the fluid and is in contact with the fluid. The liner and pressure bearing shell form a pseudo-monolithic shape in which any gap at the interface between the liner and pressure bearing shell is small enough to prevent entry of foreign materials.

[0012] Implementations can include one or more of the following features. For example, the liner and pressure bearing shell can be configured such that the shell exerts a compressive stress on the liner.

[0013] The interface between the liner and the pressure bearing shell can be at least partly conical in shape. The interface between the liner and the pressure bearing shell can be at least partly cylindrical in shape. [0014] The liner can include a tube section that extends through at least one opening of the pressure bearing shell, the tube section defining an internal passageway through which the fluid flows. The internal passageway of the tube section can be in fluid communication with a capillary of a nozzle device.

[0015] The liner and the pressure bearing shell can be sealed at an end and the liner can be pressured to a pressure greater than 25 megapascals (MPa), greater than 55 MPa, greater than 80 MPa, or greater than 100 MPa.

[0016] The pressure bearing shell can be made of a material having a coefficient of thermal expansion that matches a coefficient of thermal expansion of the material of the liner.

[0017] The interface between the liner and the pressure bearing shell can be at least partly conical in shape and can taper toward a tube section of the liner that extends through an opening of the pressure bearing shell.

[0018] The liner can be made of molybdenum or a ceramic material. The liner can be made of a material that is anisotropic and is brittle at room temperature.

[0019] The interface between the liner and pressure bearing shell can include a filler material having a melting point that is greater than a melting point of the fluid such that the filler material is in contact with both the liner and the pressure bearing shell and any gap that is formed is between this filler material and one or more of the liner and the pressure bearing shell, such gap being small enough to prevent entry of foreign materials. The filler material can cover one or more of the liner and the pressure bearing shell at the interface, and has a thickness extent that is 20-200 micrometers (pm). The filler material can have a brazing temperature of 300-400 °C. The filler material can be made of an alloy of nickel and gold.

[0020] Any gap at the interface between the liner and pressure bearing shell can be small enough to prevent entry of oxygen.

[0021] The pressure bearing shell can be made of a material that is more ductile than the liner material, and a ratio of the yield strength to the ultimate strength of the pressure bearing shell material can be between 0.4 and 0.6.

[0022] In other general aspects, a pressure vessel is configured to retain a fluid that includes tin. The pressure vessel includes: a liner made of molybdenum, the liner defining a liner cavity that retains the tin fluid and is in contact with the tin fluid; and a pressure bearing shell defining a shell cavity in which the liner is fixed. The pressure bearing shell is made of a material having a coefficient of thermal expansion that matches a coefficient of thermal expansion of the molybdenum.

[0023] Implementations can include one or more of the following features. For example, the shell material can be made of an alloy of iron. The alloy of iron can include nickel, cobalt, and iron. The alloy of iron can be Kovar™. [0024] The liner and pressure bearing shell can be configured such that the shell exerts a compressive stress on the liner.

[0025] The interface between the liner and the pressure bearing shell can be at least partly conical in shape. The interface between the liner and the pressure bearing shell can be at least partly cylindrical in shape.

[0026] The liner can include a tube section that extends through at least one opening of the pressure bearing shell, the tube section defining an internal passageway through which the tin fluid flows. The internal passageway of the tube section can be in fluid communication with a capillary of a nozzle device.

[0027] The liner and the pressure bearing shell can be sealed at an end and the liner can be pressured to a pressure greater than 25 megapascals (MPa), greater than 55 MPa, greater than 80 MPa, or greater than 100 MPa.

[0028] The interface between the liner and the pressure bearing shell can be at least partly conical in shape and taper toward a tube section of the liner that extends through an opening of the pressure bearing shell.

DESCRIPTION OF DRAWINGS

[0029] The accompanying drawings, which are incorporated herein and form part of the specification, illustrate the present disclosure and, together with the description, further serve to explain the principles of the aspects of this disclosure and to enable a person skilled in the relevant art(s) to make and use the aspects of this disclosure.

[0030] Fig. 1 A is a schematic diagram of a pressure vessel configured to retain a fluid and to maintain a high-pressure environment for the fluid, the pressure vessel including a liner within a pressure bearing shell;

[0031] Fig. IB is a schematic diagram of the pressure bearing shell of the pressure vessel of Fig. 1A;

[0032] Fig. 1C is a schematic diagram of the liner of the pressure vessel of Fig. 1A;

[0033] Fig. ID is a close-up cross-sectional view showing an interface between the liner and the pressure bearing shell of Fig. 1 A;

[0034] Fig. 2A is a schematic diagram of the pressure vessel of Fig. 1A, showing the compressive stress applied to the liner from the pressure bearing shell;

[0035] Fig. 2B is a cross-sectional schematic view of the pressure vessel of Fig. 2A taken along plane 2B-2B and showing the compressive stress applied to the liner from the pressure bearing shell; [0036] Fig. 3 is a schematic view of the pressure vessel of Fig. 1A, depicting how a first end is sealed with a structure and a liner cavity is pressurized by way of a pressure port at the structure;

[0037] Fig. 4A is a cross-sectional view of an implementation of the pressure vessel of Figs. 1 A-3, in which an interface between the liner and the pressure bearing shell has a cylindrical shape; [0038] Fig. 4B is a cross-sectional view of the pressure vessel of Fig. 4A taken along plane 4B-4B; [0039] Fig. 5A is a cross-sectional view of an implementation of the pressure vessel of Figs. 1 A-3, in which at least a part of an interface between the liner and the pressure bearing shell has a conical shape;

[0040] Fig. 5B is a cross-sectional view of the pressure vessel of Fig. 5B taken along plane 5B-5B; [0041] Fig. 5C is a cross-sectional view of the pressure vessel of Fig. 5A in a disassembled state;

[0042] Fig. 6A is a cross-sectional view of an implementation of the pressure vessel of Figs. 1 A-3, in which at least a part of an interface between the liner and the pressure bearing shell has a conical shape and at least part of the interface between the liner and the pressure bearing shell includes a filler material;

[0043] Fig. 6B is a cross-sectional view of the pressure vessel of Fig. 6B taken along plane 6B-6B;

[0044] Fig. 6C is a close-up view of the interface between the liner and the pressure bearing shell of Fig. 6A;

[0045] Fig. 7A is a cross-sectional view of a first step in assembly of the pressure vessel of Fig. 6A, in which the liner is inserted into the pressure bearing shell;

[0046] Fig. 7B is a cross-sectional view of the first step in the assembly of the pressure vessel of Fig. 7B taken along the plane 7B-7B;

[0047] Fig. 7C is a close-up view of the interface between the liner and the pressure bearing shell of Fig. 7A;

[0048] Fig. 7D is a cross-sectional view of a second step in assembly of the pressure vessel of Fig. 6A, in which a filler material is brazed between the pressure bearing shell and the liner;

[0049] Fig. 8 is a block diagram of a fluid supply apparatus configured to supply target material to a target location in a chamber of an extreme ultraviolet light source, the fluid supply apparatus including a pressure vessel of any one of Figs. 1A-6C; and

[0050] Fig. 9 is a block diagram of a fluid supply apparatus and an extreme ultraviolet light source, in which the fluid supply apparatus includes a nozzle supply system in which the pressure vessel is arranged and fluid coupled to a nozzle device of the nozzle supply system.

DESCRIPTION

[0051] Referring to Fig. 1A, a pressure vessel 100 is configured to retain a fluid 50 and to maintain, at various times, a high-pressure environment for the fluid 50. For example, a high-pressure environment may include pressures that are greater than 1 megapascal (MPa). The pressure vessel 100 includes a liner 105 (also shown in Fig. IB) that defines a liner cavity 106 that retains the fluid 50 such that the fluid 50 is in contact with an inner surface 107 of the liner 105. Because the fluid 50 and the inner surface 107 of the liner 105 are in contact with each other, the liner 105 is made of a material that is compatible with the fluid 50. In order to be compatible, the material of the liner 105 has minimal or no chemically reactivity to the fluid 50. Furthermore, the material of the liner 105 should have a melting point or range of melting points that is greater than the melting point or range of melting points of the fluid 50. Depending on the fluid 50, this means that the liner 105 may need to be made of a material that is not suited for use in a pressure vessel. That is, the liner 105 may need to be made of a material that is too brittle and/or is unsuitable for use at the high pressures (for example, greater than 1 MPa) that are needed for use in a pressure vessel.

[0052] As an example, if the fluid 50 is made of tin or a tin alloy that is maintained in a fluid state, and therefore is kept at a temperature greater than about 230 °C, then the liner 105 can be made of molybdenum. Molybdenum is non-reactive with tin and has a melting point above 230 °C. Unfortunately, molybdenum is a brittle anisotropic material at room temperatures and, even though it undergoes a brittle to ductile transition at 150-200 °C, molybdenum is still too brittle to be used in a pressure bearing capacity even at temperatures above 230 °. In particular, molybdenum would suffer from brittle fracture at the temperatures and high pressures required in a pressure vessel environment. [0053] In order to be able to use a material for the liner 105 that is not suited for use in a pressure vessel or that suffers from brittle fracture, such as when there is a need to ensure that the material for the liner 105 is compatible with the fluid 50, the pressure vessel 100 includes a shell 110 (also shown in Fig. 1C) into which the liner 105 is fixed. The shell 110 is pressure bearing, which means that it is able to bear or withstand the high pressures that are required for the pressure vessel environment. The pressure bearing shell 110 is ductile and functions to prevent fractures even when operating the pressure vessel 100 at the higher pressures, such as above 1 MPa. Thus, in this way, the overall pressure vessel 100 can comply with governmental directives relating to use of pressure vessels even though the liner 105 alone does not comply.

[0054] An interface 108 is formed at the three-dimensional border between the liner 105 and the pressure bearing shell 110. The interface 108 is the three-dimensional location at which the liner 105 and the pressure bearing shell 110 meet. Moreover, the liner 105 and the pressure bearing shell 110 form a pseudo-monolithic shape, which means that even though there is the interface 108 between the liner 105 and the pressure bearing shell 110, the overall shape (the combination of the liner 105 and the pressure bearing shell 110) functions similarly to a monolithic shape made of a single bulk material. Referring also to Fig. ID, any gap 109 that is formed at the interface 108 between the liner 105 and the pressure bearing shell 110 is small enough to prevent entry of foreign materials. For example, three different types of foreign materials 111, 112, 113 are shown in Fig. ID. The size of the gap 109 corresponds to a distance measured along a direction that extends between an outer surface 105o of the liner and an inner surface HOi of the pressure bearing shell 110. This direction is parallel with the X axis of a Cartesian coordinate system shown in Figs. 1A-D. To put it another way, the outer surface 105o of the liner 105 is essentially continuously conterminous with the inner surface 1 lOi of the pressure bearing shell 110 and the interface 108 is so tight that entry of these foreign materials 111, 112, 113 is prevented or substantially reduced. Specifically, the extent of each of the foreign materials 111, 112, 113 is larger than the size of the gap 109; in this way, the foreign materials 111, 112, 113 are unable to enter the volume defined by the gap 109.

[0055] For example, foreign materials that can form or exist adjacent to the pressure vessel 100 are water vapor (HjO), oxygen (O2), and oxides that form from the fluid 50. Such materials can be corrosive and damaging, and, in prior pressure vessels, such materials can become trapped within the gap between the liner and the outer shell, and can be difficult to remove, once they have been trapped. These trapped materials can migrate into the interior or cavity of the pressure vessel to thereby contaminate the fluid 50. The contamination of these materials within the fluid 50 can cause clogs and fractures within components of prior pressure vessels and also components that are downstream of the pressure vessel. As discussed herein, the pressure vessel 100 is designed in a manner that prevents these foreign materials from becoming trapped within the gap 109 between the liner 105 and the pressure bearing shell 110.

[0056] Referring to Fig. IB, the pressure bearing shell 110 defines a shell cavity 114 into which the liner 105 is fixed. In order to reduce changes in the size of the gap 109 that could be caused from changes in the temperature of one or more of the liner 105 and the pressure bearing shell 110, the pressure bearing shell 110 is made of a material that has a coefficient of thermal expansion that matches a coefficient of thermal expansion of the liner 105. For example, if the fluid 50 is made of tin or an alloy of tin, the liner 105 can be made of molybdenum or a ceramic material (both of which are non-reactive with the tin). In this case, the pressure bearing shell 110 is made of an alloy of iron, such as an alloy of nickel, cobalt, and iron. In one specific example, the pressure bearing shell 110 is made of Kovar™.

[0057] As mentioned above, the liner 105 can be made of a material such as molybdenum that is brittle and anisotropic at room temperature. In particular, the brittleness of the material of the liner 105 can be described in terms of its ductility. Ductility is a physical property of a material associated with the ability to be stretched or deformed without breaking. Ductility is an indication of how much plastic strain a material can withstand before it breaks. A ductile material can withstand large strains even after it has begun to yield. Thus, a ductile substance can be deformed by a substantial amount without breaking. On the other hand, a brittle material such as molybdenum may stretch or deform in failure, but such stretching and deformity by molybdenum is minimal such that it would not be able to withstand a large plastic deformation before fracturing or separating. That is, the material of the liner 105 is not ductile enough to function in a pressure bearing capacity. On the other hand, the pressure bearing shell 110 is made of a material that is more ductile than the material of the liner 105.

Additionally, the material of the pressure bearing shell 110 is such that it can withstand a large plastic deformation before it fractures (or separates). The pressure bearing shell 110 is ductile enough to function in a pressure bearing capacity. [0058] In some implementations, the ductility of the material of the pressure bearing shell 110 is quantified by three properties: yield strength, ultimate strength, and elongation at break. The yield strength is the maximum stress that the material can withstand when it is deformed (within its elastic limit). The ultimate strength is the maximum stress that the material can withstand before its failure. The elongation at the break is a quantification of how much plastic deformation the material can tolerate before catastrophic failure. A ductility of the material of the pressure bearing shell 110 can be quantified using these properties as follows. In some implementations, a ratio of the yield strength to the ultimate strength of the material of the pressure bearing shell 110 is between 0.4 and 0.6.

[0059] Referring to Figs. 2 A and 2B, in some implementations, the pressure bearing shell 110 exerts a compressive stress on the liner 105. Specifically, the compressive stress is exerted on the liner 105 in the XZ plane (of the XYZ Cartesian coordinate system shown in Figs. 2A and 2B). The compressive stress is depicted in the form of arrows 217 that extend from the pressure bearing shell 110 to the liner 105.

[0060] In some implementations, the compressive stress 217 can arise by shrink fitting the pressure bearing shell 110 to the liner 105. In these implementations, with reference to Figs. IB and 1C, when the pressure bearing shell 110 and the liner 105 are at the same temperature (for example, at room temperature, or at a temperature at which the pressure vessel 100 is operated), an inner extent ID110 of the pressure bearing shell 110 is smaller than an outer extent OD105 of the liner 105. During manufacture of the pressure vessel 100, the pressure bearing shell 110 is heated until its inner extent ID110 becomes larger than the outer extent OD105 of the liner 105. At this time, the liner 105 is inserted into the pressure bearing shell 110, and temperature of the liner 105 and the pressure bearing shell 110 are permitted to equalize with each other. Once the temperature of the liner 105 and the pressure bearing shell 110 is equalized, they form the pseudo-monolithic shape of the pressure vessel 100.

[0061] In other implementations, as discussed below with reference to Figs. 6A-7B, the compressive stress 217 can be affected by adding a filler material.

[0062] In some implementations, such as shown in Fig. 3, the pressure vessel 100 is sealed at a first end 115 with a structure 117 such as a flange, sealing device, valve, or fluid flow component. A second end 116 of the pressure vessel 100 may be sealed or may be open to provide a controlled escape of the fluid 50 from the pressure vessel 100 to another device. As discussed below, for example, the second end 116 can include an opening that is in fluid communication with a nozzle. The liner cavity 106 can be pressurized (via a pressure port 120) to a pressure greater than 25 MPa, greater than 55 MPa, greater than 80 MPa, or greater than 100 MPa using, for example, an inert gas such as argon (Ar) and hydrogen (Hz). Moreover, the fluid 50 can be flowed into the liner cavity 106 through a fluid passage 120 within the structure 117. [0063] Referring to Figs. 4A and 4B, an implementation 400 of the pressure vessel 100 is shown. The pressure vessel 400 is designed with an overall cylindrical shape in which a three-dimensional interface 408 between the liner 405 and the pressure bearing shell 410 is cylindrical in shape. The liner 405 defines a liner cavity 406 in which the fluid 50 (not shown in Figs. 4A and 4B) can be retained. The liner 405 includes a first end 415 that can be sealed (such as shown in Fig. 3) with a structure 417 that can include a pressure port 420. Moreover, fluid 50 can be flowed into the liner cavity 406 through the structure 417 or through the liner 405 and the pressure bearing shell 410, depending on the application.

[0064] The pressure vessel 400 includes a second end 416 that is in fluid communication with a nozzle device, such as discussed below with reference to Figs. 8 and 9. To this end, the liner 405 includes a tube section 421 that extends through at least one opening 422 of the pressure bearing shell 410. The tube section 421 defines an internal passageway 423 in fluid communication with the liner cavity 406 and also to the nozzle device such that the fluid 50 is able to flow through the internal passageway 423. In this way, the fluid 50 flows generally along the -Y direction within the system that includes the pressure vessel 400, such that the fluid 50 enters the liner cavity 406 through the structure 417 (or the liner 405 and the pressure bearing shell 410), and the fluid 50 remains in the liner cavity 406 until being directed out of the liner cavity 406 toward the nozzle device by way of the internal passageway 423.

[0065] Referring to Figs. 5A-5C, an implementation 500 of the pressure vessel 100 is shown. The pressure vessel 500 is designed with an overall cylindrical shape as the pressure vessel 400. However, in the pressure vessel 500, an interface 508 defined between the liner 505 and the pressure bearing shell 510 is at least partly conical in shape, such interface 508 corresponding to the three-dimensional shape formed at the boundary between the liner 505 and the pressure bearing shell 510. Thus, an outer surface 505o of the liner 505 has a conical shape that matches a conical shape of an inner surface 5 lOi of the pressure bearing shell 510. The liner 505 defines a liner cavity 506 in which the fluid 50 (not shown in Figs. 5A and 5B) can be retained. The liner 505 includes a first end 515 that can be sealed (such as shown in Fig. 3) with a structure 517 that can include a pressure port 520. Moreover, fluid 50 can be flowed into the liner cavity 506 through the structure 517 or through the liner 505 and the pressure bearing shell 510, depending on the application.

[0066] The pressure vessel 500 includes a second end 516 that is in fluid communication with a nozzle device, such as discussed below with reference to Figs. 8 and 9. To this end, the liner 505 includes a tube section 521 that extends from a transverse surface 505t of the liner 505 and through at least one opening 522 of the pressure bearing shell 510. The tube section 521 defines an internal passageway 523 in fluid communication with the liner cavity 506 and also to the nozzle device such that the fluid 50 is able to flow through the internal passageway 523. In this way, the fluid 50 flows generally along the -Y direction within the system that includes the pressure vessel 500, such that the fluid 50 enters the liner cavity 506 through the structure 517 (or the liner 505 and the pressure bearing shell 510), and the fluid 50 remains in the liner cavity 506 until being directed out of the liner cavity 506 toward the nozzle device by way of the internal passageway 523.

[0067] As mentioned, the interface 508, which is that three-dimensional shape formed at the boundary between the liner 505 and the pressure bearing shell 510, is partly conical or fully conical in shape. In this example, the interface 508 tapers toward the tube section 521. Referring to Fig. 5C, the conical design of the interface 508 (which is due to the conical shape of the mating surfaces, that is, the outer surface 505o of the liner 505 and the inner surface 5 lOi of the pressure bearing shell 510) can provide some advantages during manufacture of the pressure vessel 500. In particular, the tapered interface 508 can enable greater tolerances during mating of the liner 505 to the pressure bearing shell 510. As the liner 505 is inserted into the shell cavity 514, the outer surface 505o of the liner 505 slides across the inner surface 5 lOi of the pressure bearing shell 510 until the transverse surface 505t of the liner 505 makes contact with a transverse surface 5 lOt of the pressure bearing shell 510.

[0068] Referring to Figs. 6A-6C, an implementation 600 of the pressure vessel 100 is shown, in which an interface 608 between a liner 605 and a pressure bearing shell 610 includes a filler material 625. Similar to the pressure vessel 500, the interface 608 is partly conical or fully conical in shape and tapers toward a tube section 621 through which the fluid 50 is able to flow from a liner cavity 606 defined by the liner 605. The filler material 625 has a melting point that is greater than a melting point or range of the fluid 50 that flows through the liner cavity 606. In this way, the filler material 625 remains solid when the pressure vessel 600 is being used. The filler material 625 is in contact with both the liner 605 and the pressure bearing shell 610. In particular, the filler material 625 contacts an outer surface 605o of the liner 605 and an inner surface 6 lOi of the pressure bearing shell 610. Any gap that is formed between the filler material 625 and either of the liner 605 and the pressure bearing shell 610 is small enough to prevent entry of foreign materials, such as the foreign materials 111, 112, 113 (Fig. ID). In some implementations, the filler material 625 can have an extent 626 of 20-200 micrometers (pm). The extent 626 is a measure of the thickness of the filler material 625 in a direction taken along the normal to the outer surface 605o and the inner surface 610i.

[0069] The filler material 625 is desirably a material that is able to adhere to either the liner 605 or the pressure bearing shell 610. Moreover, the filler material 625 should be non-reactive to the materials of the liner 605, the pressure bearing shell 610, and the fluid 50. In some implementations, the filler material 625 is metallurgically compatible with the material of the liner 605 and the pressure bearing shell 610. In some implementations, the filler material 625 includes an alloy of nickel and gold.

[0070] Referring to Figs. 7A-7D, in some implementations, to assemble the pressure vessel 600, the liner 605 is inserted into the shell cavity 614 until a transverse surface 605t (Fig. 6A) of the liner 605 makes contact with a transverse surface 6 lOt (Figs. 7A and 7B) of the pressure bearing shell 610. In these implementations, the compressive stress that the pressure bearing shell 610 applies to the liner 605 arises due to the application of the filler material 625 in the gap at the interface 608 between the liner 605 and the pressure bearing shell 610. The filler material 625 can be applied to the gap at the interface 608 using brazing, as shown in Fig. 7D. The filler material 625 (which is supplied from a source 627) is heated above its melting point (or brazing temperature) but below the melting point of the materials of the liner 605 and the pressure bearing shell 610. The filler material 625 is drawn into or distributed within the gap at the interface 608 by way of capillary action. Additionally, the brazing temperature of the filler material 625 is desirably above the melting point or range of the fluid 50 to ensure that the filler material 625 remains solid during use of the pressure vessel 600, which can require that the temperature remains above the melting range of the fluid 50 at various times. In the implementation in which the fluid 50 include tin or a tin alloy, the brazing temperature of the filler material 625 can be between 300-400 °C. Once the gap at the interface 608 is filled with filler material 625, the filler material 625 is permitted to cool, thus joining the liner 605 and the pressure bearing shell 610, as shown in Figs. 6A-6C. In this way, the interface 608 is impervious to foreign materials, such as the foreign materials 111, 112, 113 shown in Fig. ID.

[0071] Referring to Fig. 8, a pressure vessel 800, which can be the pressure vessel 100, 400, 500, or 600, is configured for use in a fluid supply apparatus 830. The fluid supply apparatus 830 is configured to supply target material 850 to a target location 854 in cavity 856 of a chamber 858 of an extreme ultraviolet (EUV) light source. The fluid supply apparatus 830 includes a priming system 832, a reservoir system 836, and a nozzle supply system 840. The priming system 832 is configured to receive a solid matter 834 that includes or forms the target material 850 and to produce the target material 850 from the solid matter 834. The reservoir system 836 includes one or more fluid reservoirs 838 in fluid communication with the priming system 832 and also the nozzle supply system 840. The reservoirs 838 are configured to store the target material 850. The nozzle supply system 840 produces and supplies the target material 850 to the target location 854. The pressure vessel 800 can be within any one or more of the priming system 832, the reservoir system 836, and the nozzle supply system 840. In some implementations, the pressure vessel 800 is a part of the nozzle supply system 840.

[0072] In operational use, the nozzle supply system 840 delivers the target material 850 in the form of a stream 851 of particles 852 or targets to the target location 854 along a path. The target material 850 is formed from the solid matter 834 and is flowed through fluid supply apparatus 830. The particles 852 of the target material 850 can be, for example, droplets of liquid or molten fluid target material 850, a portion of a liquid stream of the fluid target material 850, solid particles or clusters formed from the fluid target material 850, solid particles contained within liquid droplets of the fluid target material 850, a foam produced from the fluid target material 850, or solid particles contained within a portion of a liquid stream of the fluid target material 850. The target material 850 is any material that radiates ultraviolet light (such as extreme ultraviolet light) when converted to a plasma state. The target material 850 can include, for example, water, tin, lithium, xenon, or a tin alloy. For example, the element tin can be used as pure tin (Sn); as a tin compound, for example, SnBr4, SnBrj, SnFU; as a tin alloy, for example, tin-gallium alloys, tin-indium alloys, tin-indium-gallium alloys; or any combination of these alloys. The particles 852 can be provided to the target location 854 by passing molten target material 850 through a nozzle of the nozzle supply system 840, and allowing the particles 852 to drift along the path into the target location 854. In some implementations, the particles 852 can be directed to the target location 854 by force. Additionally, the particle 852 that interacts with the radiation pulse within the target location 854 can also have already interacted with one or more prior radiation pulses. Or, the particle 852 that interacts with the radiation pulse within the target location 854 can reach the target location 854 without having interacted with any other radiation pulses.

[0073] Referring to Fig. 9, an implementation 960 of an EUV light source is shown. As discussed, the nozzle supply system 840 of the fluid supply apparatus 830 delivers the target material 850 in the form of the stream 851 of particles 852 to the target location 854 within a chamber 858 of the EUV light source 960. The interaction of the particles 852 of the target material 850 with radiation pulses of a light beam 961 at the target location 854 creates a plasma 962 that produces EUV light 963. The light beam 961 can be generated by an optical source 964. The EUV light 963 that is generated by the interaction between the radiation pulses of the light beam 961 and the particles 852 is collected by a collector 965, which supplies the EUV light 963 to a lithography exposure apparatus 966. The collector 965 can be, for example, in the shape of a ellipsoid that has a first focus within the target location 854 and a second focus at an intermediate point 967 (also called the intermediate focus) at which the EUV light 963 is output from the EUV light source 960 and input to the lithography exposure apparatus 966. The lithography exposure apparatus 966 can be an integrated circuit lithography tool that uses the EUV light 963, for example, to process a silicon wafer work piece 968 in a known manner. The silicon wafer work piece 968 is then additionally processed in a known manner to obtain an integrated circuit device.

[0074] In the implementation of Fig 9 the pressure vessel 800 is arranged within the nozzle supply system 840. As shown also in Fig. 8, the pressure vessel 800 is arranged so that the tube section 821 of the liner 805 that extends through at least one opening of the pressure bearing shell 810. The tube section 821 defines an internal passageway through which the fluid target material 850 and this internal passageway is fluidly couples with a capillary 968 of a nozzle device 970 of the nozzle supply system 840 so that the capillary 968 is in fluid communication with the liner cavity 806 of the pressure vessel 800.

[0075] As discussed above, the pressure vessel 800 is designed in a pseudo-monolithic manner but made of two components, namely, the liner 805, which hold or retains the fluid target material 850, and the pressure bearing shell 810, which is able to bear or withstand the high pressures that are required for the pressure vessel environment. The pressure bearing shell 810 functions to prevent fractures even when operating the pressure vessel 100 at the higher pressures, such as above 1 MPa. Moreover, even though there is an interface such as interface 108 between the liner 805 and the pressure bearing shell 810, the overall shape (the combination of the liner 805 and the pressure bearing shell 810) functions similarly to a monolithic shape made of a single bulk material. As discussed above, foreign materials such as water vapor (HjO), oxygen (O2), and oxides that can form from the fluid target material 850 can be corrosive and damaging, and can become trapped within the gap and then released into the fluid target material 850 to thereby contaminate the fluid target material 850. The contamination of these foreign materials within the fluid target material 850 can cause clogs and fractures within components of the pressure vessel 800, and importantly, the nozzle device 970 and the capillary 968. In order to prevent such contamination in the nozzle device 970 and the capillary 968, as discussed above, the pressure vessel 800 is designed such that any gap that is formed at the interface between the liner 805 and the pressure bearing shell 810 is small enough to prevent entry of these foreign materials.

[0076] The implementations can be further described using the following clauses:

1. A fluid supply apparatus configured to supply target material to a target location in a chamber of an extreme ultraviolet light source, the fluid supply apparatus comprising: a priming system configured to receive a solid matter that includes the target material and to produce a fluid target material from the solid matter; a reservoir system including one or more fluid reservoirs in fluid communication with the priming system and configured to store the fluid target material; a nozzle supply system in fluid communication with the reservoir system; and a pressure vessel within one or more of the priming system, the reservoir system, and the nozzle supply system, the pressure vessel configured to retain the fluid target material, the pressure vessel comprising: a liner defining a liner cavity that retains the fluid target material under pressure, and a pressure bearing shell defining a shell cavity in which the liner is fixed; wherein the liner and pressure bearing shell form a pseudo-monolithic shape in which any gap at the interface between the liner and pressure bearing shell is small enough to prevent entry of foreign materials.

2. The fluid supply apparatus of clause 1, wherein the liner and the pressure bearing shell are configured such that the shell exerts a compressive stress on the liner.

3. The fluid supply apparatus of clause 1, wherein the interface between the liner and the pressure bearing shell is at least partly conical in shape or is cylindrical in shape.

4. The fluid supply apparatus of clause 1, wherein the liner includes a tube section that extends through at least one opening of the pressure bearing shell, the tube section defining an internal passageway through which the fluid target material flows. 5. The fluid supply apparatus of clause 1, wherein the nozzle supply system includes a nozzle device including a capillary through which the fluid target material is flowed, the capillary being in fluid communication with the liner cavity of the pressure vessel.

6. The fluid supply apparatus of clause 1, wherein the liner and the pressure bearing shell are sealed at an end and the liner is pressured to a pressure greater than 25 megapascals (MPa), greater than 55 MPa, greater than 80 MPa, or greater than 100 MPa.

7. The fluid supply apparatus of clause 1, wherein the fluid target material is tin or an alloy of tin; the liner is made of molybdenum, and the pressure bearing shell is made of a material having a coefficient of thermal expansion that matches a coefficient of thermal expansion of the molybdenum.

8. The fluid supply apparatus of clause 7, wherein the pressure bearing shell is made of an alloy of iron.

9. A pressure vessel configured to retain a fluid, the pressure vessel comprising: a liner made of a material that is compatible with the fluid, the liner defining a liner cavity that retains the fluid and is in contact with the fluid; and a pressure bearing shell defining a shell cavity in which the liner is fixed; wherein the liner and pressure bearing shell form a pseudo-monolithic shape in which the interface between the liner and pressure bearing shell is tight enough to prevent entry of foreign materials.

10. The pressure vessel of clause 9, wherein the liner and pressure bearing shell are configured such that the shell exerts a compressive stress on the liner.

11. The pressure vessel of clause 9, wherein the interface between the liner and the pressure bearing shell is at least partly conical in shape or is cylindrical in shape.

12. The pressure vessel of clause 9, wherein the liner includes a tube section that extends through at least one opening of the pressure bearing shell, the tube section defining an internal passageway through which the fluid flows.

13. The pressure vessel of clause 12, wherein the internal passageway of the tube section is in fluid communication with a capillary of a nozzle device.

14. The pressure vessel of clause 9, wherein the liner and the pressure bearing shell are sealed at an end and the liner is pressured to a pressure greater than 25 megapascals (MPa), greater than 55 MPa, greater than 80 MPa, or greater than 100 MPa.

15. The pressure vessel of clause 9, wherein the pressure bearing shell is made of a material having a coefficient of thermal expansion that matches a coefficient of thermal expansion of the material of the liner.

16. The pressure vessel of clause 9, wherein the interface between the liner and the pressure bearing shell is at least partly conical in shape and tapers toward a tube section of the liner that extends through an opening of the pressure bearing shell.

17. The pressure vessel of clause 9, wherein the liner is made of molybdenum or a ceramic material. 18. The pressure vessel of clause 9, wherein the interface between the liner and pressure bearing shell includes a filler material having a melting point that is greater than a melting point of the fluid such that the filler material is in contact with both the liner and the pressure bearing shell and any gap that is formed is between this filler material and one or more of the liner and the pressure bearing shell, such gap being small enough to prevent entry of foreign materials, wherein the filler material covers one or more of the liner and the pressure bearing shell at the interface, and has a thickness extent that is 20-200 micrometers (pm).

19. The pressure vessel of clause 18, wherein the filler material has a brazing temperature of 300-400 °C.

20. The pressure vessel of clause 18, wherein the filler material is made of an alloy of nickel and gold.

21. The pressure vessel of clause 9, wherein the interface between the liner and pressure bearing shell is tight enough to prevent entry of oxygen.

22. The pressure vessel of clause 9, wherein the pressure bearing shell is made of a material that is more ductile than the liner material, and a ratio of the yield strength to the ultimate strength of the pressure bearing shell material is between 0.4 and 0.6.

23. The pressure vessel of clause 9, wherein the liner is made of a material that is anisotropic and is brittle at room temperature.

24. A pressure vessel configured to retain a fluid that includes tin, the pressure vessel comprising: a liner made of molybdenum, the liner defining a liner cavity that retains the tin fluid and is in contact with the tin fluid; and a pressure bearing shell defining a shell cavity in which the liner is fixed, the pressure bearing shell made of a material having a coefficient of thermal expansion that matches a coefficient of thermal expansion of the molybdenum.

25. The pressure vessel of clause 24, wherein the shell material is made of an alloy of iron.

26. The pressure vessel of clause 25, wherein the alloy of iron comprises nickel, cobalt, and iron.

27. The pressure vessel of clause 25, wherein the alloy of iron is Kovar.

28. The pressure vessel of clause 24, wherein the liner and pressure bearing shell are configured such that the shell exerts a compressive stress on the liner.

29. The pressure vessel of clause 24, wherein the interface between the liner and the pressure bearing shell is at least partly conical in shape or is cylindrical in shape.

30. The pressure vessel of clause 24, wherein the liner includes a tube section that extends through at least one opening of the pressure bearing shell, the tube section defining an internal passageway through which the tin fluid flows.

31. The pressure vessel of clause 30, wherein the internal passageway of the tube section is in fluid communication with a capillary of a nozzle device. 32. The pressure vessel of clause 24, wherein the liner and the pressure bearing shell are sealed at an end and the liner is pressured to a pressure greater than 25 megapascals (MPa), greater than 55 MPa, greater than 80 MPa, or greater than 100 MPa.

33. The pressure vessel of clause 24, wherein the interface between the liner and the pressure bearing shell is at least partly conical in shape and tapers toward a tube section of the liner that extends through an opening of the pressure bearing shell.

34. A shrunk-fit fluid supply apparatus formed of a liner disposed in a pressure bearing shell to form a unitary member, the liner defining a liner outer diameter and the pressure bearing shell defining an inner diameter, wherein the pressure bearing shell is formed of a material adapted to expand when heated to increase the inner diameter to be greater than the outer diameter of the liner, and adapted to shrink to decrease the inner diameter when cooled to thereby squeeze the liner and form the unitary member.