Insert for a chamber wall of a source chamber of an EUV radiation source

Abstract

An insert (8) for a chamber wall of a source chamber (2) of an EUV radiation source (1) has a contact section (31) of a contact surface against which a contact element (50) rests flatly.

Description

[0001] The invention relates to an insert for a chamber wall of a source chamber of an EUV radiation source. The invention further relates to an EUV radiation source with such an insert, an illumination system with such an EUV radiation source, a projection exposure system, and a metrology system with a corresponding illumination system.

[0002] In an EUV radiation source, useful radiation in the EUV range can be generated by igniting a source plasma in a source chamber of the EUV radiation source. US 2011 / 0089834 A1 describes an embodiment of an EUV radiation source with an electrode plasma generation device. EP 1 774 838 B1 discloses an inductively coupled plasma source.

[0003] EUV radiation sources are used in lighting systems for projection exposure systems, particularly for EUV lithography, inspection systems, and metrology systems. A corresponding projection exposure system is known, for example, from WO 2009 / 100 856 A1.

[0004] DE 10 2020 206 876 A1 discloses an EUV radiation source with a multi-part insert in a chamber wall of a source chamber. DE 10 2021 207 565 B3 discloses a further embodiment of an EUV radiation source with an insert in a wall of a source chamber.

[0005] One object of the invention is to improve an insert for a chamber wall of a source chamber of an EUV radiation source. The insert is to be improved, in particular, with regard to heat dissipation.

[0006] This problem is solved by an insert according to the invention.

[0007] According to one aspect of the invention, the insert has a contact surface against which a contact element rests flatly.

[0008] The contact element can also be fully integrated into the insert. In particular, the contact element can be milled into the carrier. Preferably, the radial geometry is milled first. Subsequently, the individual spring elements can be milled free.

[0009] The contact element can, in particular, have at least a section of a surface which forms sections of a cylindrical or conical shell. Curved surfaces are also possible in principle.

[0010] The inner insert is also called the bore insert. The outer insert, which is inserted into the wall of a source chamber of an EUV radiation source, is also called the carrier. Together, the carrier and the inner insert are referred to as the bore. The carrier may have a copper base. The bore insert may be made of ceramic.

[0011] This can improve the thermal conductivity and / or electrical conductivity, especially between the insert and the surrounding chamber wall of the source chamber.

[0012] A planar system is understood to mean, in particular, a system in which the contact surface has an extent of at least 1 mm, in particular at least 2 mm, in particular at least 3 mm, in particular at least 5 mm, in particular at least 1 cm in each of two mutually perpendicular directions. The contact surface can, in particular, be at least 50 mm² in each direction. 2 , in particular at least 100 mm 2 , in particular at least 200 mm 2 , in particular at least 300 mm 2 , in particular at least 500 mm 2 , in particular at least 1 cm 2 , in particular at least 2 cm 2 , in particular at least 3 cm 2 , in particular at least 5 cm 2 be.

[0013] The contact surface can be square, especially rectangular, or hexagonal.

[0014] The contact element can make contact with the mating surface in multiple areas. In particular, it can have a flat contact surface at each end. The end contact surface can be cylindrical or cone-shaped.

[0015] According to one aspect, the contact element can be designed to be elastically springy.

[0016] A spring ring can be used as a contact element.

[0017] The contact element can be manufactured as a bent or stamped part.

[0018] In particular, it can be made from a part with a surface designed as a freeform surface.

[0019] This allows for a particularly high degree of flexibility in shaping the contact element.

[0020] According to one aspect, the plant section can be located at an inner end of the insert in the longitudinal direction.

[0021] The inner end, in this context, refers specifically to the end of the insert facing the source chamber.

[0022] The insert has a smaller outer diameter at the inner end than at the outer end.

[0023] According to one aspect of the invention, the insert consists of a material that conducts heat well and / or electricity well.

[0024] A material with good thermal conductivity is understood to mean, in particular, a material with a thermal conductivity coefficient of at least 100 W / mK, in particular at least 200 W / mK, in particular at least 300 W / mK, in particular at least 400 W / mK.

[0025] A material that conducts electricity well is, in particular, a material with a conductivity of at least 5 × 10⁻⁶. 6 S / m, in particular at least 1 · 10 7 S / m, in particular at least 3 · 10 7 S / m, in particular at least 5 · 10 7 S / m understood.

[0026] The insert can consist in particular of silver and / or copper and / or aluminum and / or compounds of these elements.

[0027] The insert can be made of a material with a thermal coefficient and / or electrical conductivity at least as high as that of aluminum, copper, and especially as high as that of silver.

[0028] The application according to the invention can lead to the improvement of an EUV radiation source, in particular an EUV xenon plasma source.

[0029] According to one aspect, the contact element can lie flat against the chamber wall.

[0030] It can lie flat against the chamber wall, especially in a central area.

[0031] The contact element can make full contact with both the insert and the chamber wall. This allows for particularly good heat dissipation.

[0032] According to one aspect, the contact element can be pre-tensioned in the inserted state.

[0033] This allows for particularly good thermal and / or electrical contact between the insert and the chamber wall.

[0034] Preloading the contact element can compensate for thermal deformations of the insert and / or the chamber wall.

[0035] An EUV radiation source as described above leads to an improved lighting system and thus to an improvement of a projection exposure system or a metrology system.

[0036] Further advantages and details of the invention will become apparent from the description of an exemplary embodiment with reference to the figures.

[0037] They show: Fig. 1. A schematic cross-sectional drawing of an EUV radiation source, Fig. 2 a semi-schematic sectional view through section II from a source chamber of the EUV radiation source in the area of ​​a transmission channel, Fig. 3 a schematic view of a contact element which forms surface contacts at least when the insert is plugged in and Fig. 4 a schematic view of a molded part from which the contact element is formed according to Fig. 3 can be produced.

[0038] In Fig. Figure 1 shows a schematic sectional drawing of an exemplary embodiment of an EUV radiation source 1. Fig. Figure 2 shows a section of the same. The overall setup of the EUV radiation source 1 is merely exemplary and not intended to be restrictive to Figure 5. In particular, the arrangement of the access / maintenance openings of the radiation source may differ from the depicted design. The beam direction of the EUV radiation source 1 relative to the rest of the optics and the installation direction of the insert in the source chamber wall are independent of each other and can also be reversed.

[0039] The EUV radiation source 1 is part of an illumination system of a projection exposure system, which is not explicitly shown. For fundamental details, reference is made by way of example to DE 10 2017 212 352 A1, which is hereby fully integrated into the present application.

[0040] The EUV radiation source 1 has a two-part source chamber 2 with an upper chamber part 3 and a lower chamber part 4. A central plate 5 is located between the upper chamber part 3 and the lower chamber part 4. The central plate 5 forms a chamber wall of the source chamber 2, in particular of the upper chamber part 3.

[0041] In the following, the upper chamber part 3 will also be referred to as the source chamber.

[0042] The central plate 5 has eccentric openings 6 and a central opening 7.

[0043] The central plate 5 can be made up of multiple parts. In particular, it can have a plate 18 facing the source chamber 2, which can be subjected to high voltage, and a separate outer base plate 19.

[0044] A first insert 8 is inserted into the central opening 7. The first insert 8 forms an outer insert. The first insert 8 is also referred to as the "carrier". It has a first passage channel 10 extending in a longitudinal direction 9.

[0045] A second insert 11 is arranged in the first passage channel 10. The second insert 11 has a second passage channel 12 extending in the longitudinal direction 9. The support with the inner insert 11 is sometimes also referred to as a "bore".

[0046] The first passage channel 10 is also referred to as the outer passage channel. The second passage channel 12 is also referred to as the inner passage channel. The two passage channels 10, 12 have a common longitudinal axis 13 extending in the longitudinal direction 9.

[0047] In the operation of the EUV radiation source 1, the eccentric openings 6 and the central opening 7, in particular the passage channels 10, 12, serve for the passage of a source plasma ignited in the chamber parts 3, 4.

[0048] EUV radiation source 1 is an induction plasma current generator.

[0049] The EUV radiation source 1 is connected to components of an illumination optics system (not explicitly shown) of a projection exposure system, a mask inspection system, or a metrology system. The illumination optics are, in particular, a component of an illumination system. The illumination system may, in particular, comprise one or more mirrors, especially one or more faceted mirrors. The illumination optics serve, in particular, to direct the illumination radiation generated by the EUV radiation source 1 to a mask containing structures to be imaged. The mask is also referred to as a reticulum.

[0050] Also shown schematically is in the Fig. 1. A maintenance area 14 adjoins the EUV radiation source 1. An interface with a dome aperture 15 is provided between the maintenance area 14 and the EUV radiation source 1. For details, refer to DE 10 2017 212 352 A1, in particular. Fig. 23 and related description, referenced.

[0051] Maintenance area 14 can be sealed vacuum-tight against an external area 17 by means of a maintenance hatch 16. The maintenance hatch 16 can be opened for maintenance work. When the maintenance hatch 16 is open, access to maintenance area 14 and thus to the EUV radiation source 1 is possible. In particular, it is possible to remove the two inserts 8 and 11 from the EUV radiation source 1 through maintenance area 14, for example, to replace them.

[0052] The following will refer to the Fig. 2 and Fig. 3. Details of the first, outer insert (carrier) 8 and, in particular, the second, inner insert (bore) 11 are described. Corresponding designs of the inserts 8 and 11 are advantageous regardless of the other design details of the EUV radiation source 1.

[0053] The outer, first insert 8 is connected to the plate 18, for example, by several screws 30. It has, in particular, an electrical contact 21 with the plate 18. An O-ring may be provided in the connection area between the first insert 8 and the plate 18.

[0054] The first insert 8 is connected to the base plate 19, for example, by a plurality of screws 30. It has, in particular, an electrical contact 23 with the base plate 19. An O-ring may be provided in the contact area between the first insert 8 and the base plate 19.

[0055] The inner, second insert 11 rests circumferentially against the inner circumference of the first passage channel 10. It is arranged in the first passage channel 10 with virtually no play. However, it can be arranged to be displaceable longitudinally within the first passage channel 10.

[0056] The inner insert 11 can be thermally shrunk into the passage channel 10. The inner insert 11 can also be soldered, welded, or bonded to the passage channel 10. In particular, it can be positively and / or materially bonded to the passage channel 10.

[0057] During the Fig. In the variant shown in Figure 2, the inner insert 11 has several sections. In particular, it has a first, inner section 26 and a second, middle section 27. Sections 26 and 27 follow each other in the longitudinal direction 9. They can, in particular, be adjacent to each other in the longitudinal direction 9.

[0058] The inner section 26 and the middle section 27 can have substantially constant outer diameters along their longitudinal extent 9. In particular, they can have identical outer diameters.

[0059] The inner section 26 is sleeve-shaped. In particular, it is essentially hollow and cylindrical. However, it may have chamfers at its ends.

[0060] The middle section 27 has a smaller inner diameter dm than the inner section 26 with inner diameter di, dm < di.

[0061] The insert 8 has a facility section 31 at its longitudinally 9 inner end.

[0062] To improve the thermal contact and / or the electrical conductivity between the insert 8 and the surrounding chamber wall, a contact element may be provided. A spring ring 50 can serve as the contact element. In particular, it is a surface contact spring ring. Such a spring ring is defined as one that, in a specific arrangement of the insert 8 in a wall of the source chamber 2, not only establishes line contacts 8, but also provides surface contacts with the insert 8 and / or the chamber wall.

[0063] In the Fig. Figure 3 shows an example of such a spring ring 50 in the deformed state, which is assumed when inserting the insert 8 into the chamber wall.

[0064] The spring ring 50 has a strip-shaped or ring-shaped contact area 51.

[0065] The spring ring has a square contact area 52.

[0066] In the Fig.Figure 4 shows an example of a molded part 53 from which the spring ring can be manufactured. The molded part 53 is, in particular, a bent and integral component.

[0067] The molded part 53 can have one or more freeform surfaces.

Claims

[1] Insert (8) for a chamber wall of a source chamber (2) of an EUV radiation source (1) comprising 1.

1. a passage channel (10) extending in a longitudinal direction (9), 1.1.

1. which is surrounded on its perimeter by an insert wall, 1.

2. wherein the insert wall has at least one system section (31) with a system area, 1.

3. wherein a contact element lies flat against the mounting surface. [2] Use (8) according to claim 1, characterized by that the contact element is designed to be elastically resilient. [3] Use (8) according to any of the preceding claims, characterized by , that a spring ring (50) serves as the contact element. [4] Use (8) according to any one of the preceding claims, characterized by , that the plant section (31) is arranged at an inner end of the insert (8) in the longitudinal direction (9). [5] Use (8) according to any of the preceding claims, characterized bythat it is made of a material with a thermal conductivity of at least 100 W / mK and / or an electrical thermal conductivity of at least 5·10 4 S / m is. [6] having an EUV radiation source (1) 6.

1. a source chamber (2) with 6.1.

1. a chamber wall having at least one chamber opening, 6.1.

2. an insert placed into the chamber opening (8), 6.

2. wherein the insert (8) is configured according to any one of claims 1 to 5. [7] EUV radiation source (1) according to claim 6, characterized by that the contact element lies flat against the chamber wall. [8] EUV radiation source (1) according to claim 7, characterized by , that the contact element is pre-tensioned in the inserted state of the insert (8). [9] Lighting system for a projection exposure system, a mask inspection system or a metrology system with an EUV radiation source with an insert (8) according to any one of claims 1 to 5. [10] Featuring a projection exposure system for EUV lithography 10.

1. a lighting system according to claim 9 for illuminating a reticle arranged in an object field and 10.

2. a projection optic for imaging structures of the reticulum onto a wafer arranged in an image field. [11] Metrology system for inspecting a mask for EUV lithography with an illumination system according to claim 9.

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