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 (3) of an EUV radiation source (1) has a contact section (31) with a conical surface (32) or a contact section (31) which can be reversibly converted into a configuration with a conical outer surface (32) and / or an elastic contact element (34, 35) which is in contact with at least one contact surface.

Description

[0001] Application for a chamber wall of a source chamber of an EUV radiation source

[0002] The content of the German patent applications DE 10 2024 206 804.7, DE

[0003] 10 2024 203 897.0, DE 10 2024 203 896.2 and DE 10 2024 203 895.4 are incorporated herein by reference.

[0004] The invention relates to an insert for a chamber wall of a source chamber of an EUV radiation source. The invention also relates to an EUV radiation source with such an insert. Furthermore, the invention relates to an illumination system, a projection exposure system, a mask inspection system, or a metrology system with an EUV radiation source, as well as a projection exposure system and a metrology system with such an illumination system. Finally, the invention relates to a method for manufacturing an EUV radiation source.

[0005] 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. An inductively coupled plasma source is known from EP 1 774 838 B1.

[0006] 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. An object of the invention is to improve an EUV radiation source. In particular, an object of the invention is to improve an insert for a chamber wall of a source chamber of an EUV radiation source, especially in such a way that heat transfer and / or current transfer from the insert to the chamber wall of the source chamber is improved.

[0007] These problems are solved by an insert according to the invention or an EUV radiation source, in particular an EUV xenon plasma source, with such an insert.

[0008] The application can have an external and an internal application.

[0009] 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. Sometimes the outer carrier is simply referred to as the insert.

[0010] Together, the carrier and the inner insert (bore insert) are also referred to as the bore.

[0011] The carrier can have a base body made of copper.

[0012] The bore insert can be made of ceramic, in particular. According to one aspect, the insert can have a conical outer surface, at least in sections, or be reversibly convertible into a configuration with a conical outer surface.

[0013] This allows the contact area and pressure between the insert and the chamber wall of the source chamber to be improved, and in particular maximized.

[0014] Additional components, especially a spring ring with fins, can be omitted. This simplifies assembly and reduces costs. Furthermore, heat and current transfer can be improved. This results in reduced wear and better quality, particularly higher plasma stability and durability.

[0015] Simultaneously, the bore's conical shape allows for centering, thereby increasing positional stability. Additional measures for centering the bore are therefore unnecessary.

[0016] In the following, a conically shaped outer surface is understood to mean both an outer surface that is conically shaped in a ground state, in particular a stress-free ground state, and an outer surface that can be reversibly converted into a conical configuration.

[0017] The contact force between the insert and the chamber wall can be generated and / or adjusted by screws. In addition to or as an alternative to the insert having a conical section, an elastically designed contact element can be located on at least one contact surface of the insert. This can also improve heat transfer and / or electrical conductivity. The elastic contact element can be deformed, in particular pressed, when the insert is placed into the chamber wall.

[0018] A conically shaped outer surface is generally understood to be an outer surface with a conically shaped envelope. The outer surface does not necessarily have to be continuous, and in particular, not simply continuous. However, this is also possible.

[0019] The outer surface may have one or more slots or recesses. This can improve the deformability, in particular the reversible deformability of the insert, especially in the area of ​​the attachment section.

[0020] The longitudinal direction refers specifically to the axial direction of a passage channel formed during operation. The passage channel serves, in particular, to allow the passage of source plasma ignited in the source chamber.

[0021] The contact element can form part of the insert. It can also be designed as an additional, especially separate, part, or be considered as such. The insert can have exactly one contact section with a conically shaped outer surface. It can also have two or more such contact sections.

[0022] According to one aspect, the plant section extends longitudinally. In particular, it has a longitudinal component. The outer surface can be oriented parallel or obliquely to the longitudinal direction in its basic state.

[0023] The cone angle of the conically shaped outer surface can be up to 10°, in particular up to 20°, and especially up to 30°. It can, in principle, also be larger.

[0024] The conical angle of the insert can be specifically designed to form a recess in the chamber wall of the source chamber that is compatible with the insert. This recess in the chamber wall of the source chamber can be designed in such a way that, when the insert is inserted, a fit, in particular a positive-locking contact, is achieved between the insert and the chamber wall of the source chamber.

[0025] According to one aspect, the plant section is located at the first end of the deployment in the longitudinal direction.

[0026] The first end can be, in particular, an inner end, which, during the intended use of the insert, is located on the side facing the source chamber. The attachment section can, in particular, be arranged at an end of the insert where the insert has a smaller diameter than at the opposite end.

[0027] According to another aspect, the use in the longitudinal direction adjacent to the plant section can have at least one essentially hollow cylindrical section.

[0028] Alternatively, the insert can have a further section with a conically shaped outer surface, extending longitudinally adjacent to the system section. The cone angle of this outer surface can correspond exactly to that of the system section.

[0029] The insert can also have two or more hollow cylindrical sections.

[0030] The insert can have one or more stages. In particular, it can have one or more mounting shoulders. Through a staged design, especially through one or more mounting shoulders, the longitudinal position of the insert in the chamber wall can be precisely determined.

[0031] According to one aspect, the plant section may have one or more longitudinally extending incisions.

[0032] This can increase the elasticity of the system section. It can also increase the surface area of ​​the system section. Another important aspect is the use of a material with good thermal and electrical conductivity. For example, it can be made entirely or partially of copper and / or molybdenum.

[0033] A material with good thermal conductivity is understood to mean, in particular, a material with a thermal conductivity coefficient of at least 300 W / mK, in particular at least 340 W / mK, in particular at least 380 W / mK.

[0034] A material is considered to have good electrical conductivity if it has a conductivity of at least 3 • 10 6 S / m, in particular at least 5 • 10 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.

[0035] According to another aspect, the contact surface for the elastic contact element can extend transversely, and in particular perpendicularly, to the longitudinal direction. It can also extend radially to the longitudinal direction. The contact surface for the elastic contact element can, in particular, at least partially, be a contact shoulder of the insert.

[0036] The installation area does not need to extend exclusively in a direction perpendicular to the longitudinal direction. It can also include a section that is oriented parallel to the longitudinal direction.

[0037] A conical area, in particular the conical outer surface, can also serve as the contact surface. The outer surface can be partially or completely covered by the contact element. The insert can also be equipped with multiple elastic contact elements.

[0038] In particular, two or more longitudinally offset, and especially objectionable, contact surfaces for elastic contact elements may be provided.

[0039] The contact elements can also act as sealing elements. In particular, they can eliminate the need for additional O-rings.

[0040] The contact elements can be arranged on the insert in such a way that they deform when the insert is placed into the designated recess in the chamber wall of the source chamber due to a longitudinally acting pressing force. In this process, the material of the contact element is preferably displaced towards a central axis of the insert.

[0041] According to another aspect, the contact element can be formed or consist at least partially, and in particular completely, of a metal foil.

[0042] According to another aspect, the elastic contact element can be at least partially made of indium and / or have a doping of an electrically conductive material.

[0043] According to another aspect, a lubricant, in particular Teflon grease or ultra-high vacuum grease (UHV grease), may be applied to the contact element. The lubricant may be applied to one or both sides of the contact element. In particular, it may be applied exclusively to the outer surface of the contact element that rests against the chamber wall, exclusively to the inner surface of the contact element that rests against the insert, or to both the outer and inner surfaces of the contact element.

[0044] Instead of a lubricant, a liquid metal can also be used.

[0045] The thickness of the lubricant layer can, in particular, only support a few atomic layers.

[0046] The lubricant may be vapor-deposited onto the contact element.

[0047] The insert can also be provided with a suitable lubricant, especially on its outside, and in particular vapor-coated.

[0048] An EUV radiation source according to the invention, in particular an EUV xenon plasma source, has a source chamber with an insert placed in a chamber opening provided for this purpose, as described above.

[0049] The advantages arise from the benefits of its use.

[0050] According to one aspect, an inner wall surrounding the chamber opening is adapted to the insert's component section. In particular, the inner wall surrounding the chamber opening is designed to be complementary to the shape of the insert's component section. This ensures that when the insert is placed into the chamber opening, a press fit, and especially a positive-locking connection, is formed between the insert's component section and the surrounding inner wall of the source chamber. This can result in contact with particularly good thermal and / or electrical conductivity.

[0051] The component section, particularly its outer surface, can be brought into contact with the adjacent chamber wall, especially over a large area, and in particular across its entire surface. A contact spring with a lamellar structure is preferably not required.

[0052] The use of an EUV radiation source according to the invention for an illumination system of a projection exposure system, a mask inspection system or a metrology system leads to advantages that result from those associated with the use according to the invention.

[0053] The photomask, which is also referred to as the mask in the following, can have an aspect ratio between 1:1 and 1:3, preferably between 1:1 and 1:2, and particularly preferably between 1:1 or 1:2. The photomask can be substantially rectangular. The photomask can preferably be 5 to 7 inches long and wide, and particularly preferably 6 inches long and wide. Alternatively, the photomask can be 5 to 7 inches long and 10 to 14 inches wide, preferably 6 inches long and 12 inches wide. A further object of the invention is to improve a method for producing an EUV radiation source. This object is achieved by a method comprising the following steps:

[0054] Providing a source chamber with a chamber wall into which an insert according to the preceding description can be placed,

[0055] Deployment of a deployment as described above,

[0056] Insertion of the insert into the chamber wall, wherein the insert is deformed, in particular reversibly deformed, for or during insertion into the chamber wall.

[0057] The insert can be pre-tensioned, especially for insertion into the chamber wall.

[0058] In the case of use with an elastic contact element, this can be deformed during or before insertion into the chamber wall.

[0059] To deform the insert for insertion into the chamber wall, it can, for example, be cooled. The insert can be cooled to a temperature of at most 10 °C, in particular at most 0 °C, in particular at most -10 °C, in particular at most -50 °C, for insertion into the chamber wall.

[0060] The insert can also be pre-tensioned for insertion into the chamber wall using a mechanical clamping device. Furthermore, the insert and / or the elastic contact element can be coated with a lubricant before insertion into the chamber wall. For details, please refer to the preceding description.

[0061] Instead of a lubricant, a liquid metal can also be used.

[0062] Further details and specifics of the invention will become apparent from the description of exemplary embodiments with reference to the figures. These show:

[0063] Fig. 1 is a schematic sectional drawing of an EUV radiation source,

[0064] Fig. 2 shows a semi-schematic sectional view through section II of a source chamber of the EUV radiation source in the area of ​​a passage channel.

[0065] Fig. 3 shows a semi-schematic sectional view through section II of a source chamber of the EUV radiation source in the area of ​​a passage channel according to one variant.

[0066] Fig. 4 shows a schematic sectional view of another variant of an insert for a source chamber,

[0067] Fig. 5 shows a schematic sectional view of another variant of an insert for a source chamber and Fig. 6 shows a schematic sectional view of an elastic contact element.

[0068] Figure 1 shows a schematic sectional drawing of an exemplary embodiment of an EUV radiation source 1. Figures 2 and 3 show a detail thereof. The overall structure of the EUV radiation source 1 is merely exemplary and not intended to be restrictive. In particular, the arrangement of the access and maintenance openings of the radiation source may differ from the embodiment shown. 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.

[0069] 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 incorporated into the present application.

[0070] 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.

[0071] In the following, the upper chamber part 3 is also referred to as the source chamber. The middle plate 5 has eccentric openings 6 and a central opening 7.

[0072] 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.

[0073] 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.

[0074] 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".

[0075] 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.

[0076] 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.

[0077] The EUV radiation source 1 is an induction plasma current generator. Connected to the EUV radiation source 1 are components of an illumination optic (not explicitly shown) of a projection exposure system, a mask inspection system, or a metrology system. The illumination optic is, 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 optic serves, 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 reticle.

[0078] Figure 1 also schematically shows a maintenance area 14 adjoining 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, reference is made to DE 10 2017 212 352 A1, in particular Figure 23 and the associated description.

[0079] 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, 11 from the EUV radiation source 1 through maintenance area 14, for example, to replace them. Maintenance area 14 can also be located elsewhere.

[0080] The following section describes details of the first, outer insert (carrier) 8 and, in particular, the second, inner insert (bore) 11 with reference to Figures 2 and 3. Corresponding designs of the inserts 8 and 11 are advantageous regardless of the other design details of the EUV radiation source 1.

[0081] The outer, first insert 8 is connected to the plate 18, for example, by several screws. 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.

[0082] The first insert 8 is connected to the base plate 19 by a plurality of screws. 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.

[0083] 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.

[0084] 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.

[0085] 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. In the variant according to Figure 3, it also has an outer section 28. The sections 26, 27, and 28 follow one another in the longitudinal direction 9. In particular, they can be adjacent to each other in the longitudinal direction 9.

[0086] The inner section 26, the middle section 27, and the outer section 28 can have substantially constant outer diameters along their longitudinal extent 9. In particular, they can have identical outer diameters. The outer section 28 can be omitted, as shown in Figure 2.

[0087] The inner section 26 is sleeve-shaped. In particular, it is essentially hollow and cylindrical. However, it may have chamfers at its ends.

[0088] The middle section 27 has a smaller inner diameter dm than the inner section with inner diameter di 26, dm < di.

[0089] The outer section 28 can have a wall thickness that decreases towards the outside. In particular, it can have an inner diameter da that increases towards the outside. In particular, it can be funnel-shaped. The outer section 28 can have a longitudinal extent that is at least 30%, in particular at least 50%, in particular at least 75%, in particular at least 100% of the longitudinal extent of the middle section 27.

[0090] In the variant schematically depicted in Figure 4, the insert 8 has a contact section 31 at its longitudinally inner end 9. The contact section 31 has a conical outer surface 32. The recess in the chamber wall (not shown in Figure 4) of the source chamber is preferably designed to be complementary to this.

[0091] Section 31 of the assembly can be designed to be elastically deformable. In particular, it can deform elastically when inserted into the chamber wall. It can also be elastically deformed, especially pre-stressed, for insertion into the chamber wall.

[0092] To increase the elasticity of section 31 of the system, cuts can be made in it. These cuts can, in particular, run parallel to the longitudinal direction 9.

[0093] The conical shape improves the contact area and pressure between the insert 8 and the chamber wall.

[0094] Screws 30 can be used to fix the insert 8 in the chamber wall. Two screws 30 are shown as examples in the figures. The screws 30 can be arranged, in particular, parallel to the longitudinal direction 9. The arrangement of the screws 30 shown in the figures is merely exemplary and not to be understood as limiting.

[0095] Using the screws 33, a contact force can be generated between the insert 8 and the chamber wall, and in particular adjusted.

[0096] Furthermore, an elastic contact element 34 can be arranged on the conical outer surface 32 of the attachment section 31. However, this is not mandatory. The contact element 34 can also be provided in a variant of the insert 8 without a conical outer surface of the attachment section 31.

[0097] An elastic contact element 35 can also be provided in the region of a central, in particular cylindrical, section of the insert 8. The elastic contact element 35 extends in particular along the outer surface of the central section of the insert 8, which runs substantially parallel to the longitudinal direction 9.

[0098] The contact elements 34, 35 can also extend along a mounting shoulder 36, 37 running obliquely, in particular perpendicular to the longitudinal direction 9. A corresponding variant is shown by way of example in Figure 5.

[0099] The contact element 34, 35 can each be designed as a single piece, in particular as a simple, continuous component. It can completely surround the insert 8.

[0100] The contact elements 34, 35 can have a rectangular, parallelogram-shaped or L-shaped cross-section when cut parallel to the longitudinal direction 9.

[0101] They can also have a collar 38 that tapers conically in the longitudinal direction 9. This is shown by way of example in Figure 6.

[0102] The contact elements 34, 35 are made of a vacuum-compatible material. They are made of a material with high temperature resistance, in particular resistance to temperatures of at least 180 °C, in particular at least 200 °C, and in particular at least 230 °C. To prevent individual components from sticking together, the contact elements 34, 35 and / or the insert 8 can be provided with a lubricant, in particular a Teflon grease or an ultra-high vacuum grease.

Claims

Patent 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 inset wall has at least one system section (31) which 1.2.

1. has a conically shaped outer surface (32), or is reversibly convertible into a configuration with a conically shaped outer surface (32) and / or 1.2.

2. at least one contact surface (32, 36, 37) rests against an elastic contact element (34, 35).

2. Insert (8) according to claim 1, characterized in that the installation section (31) extends in the longitudinal direction (9).

3. Insert (8) according to one of the preceding claims, characterized in that the installation section (31) is arranged at a first end of the insert (8) in the longitudinal direction (9).

4. Insert (8) according to one of the preceding claims, characterized in that it has at least one substantially hollow cylindrical section adjacent to the installation section (31) in the longitudinal direction (9).

5. Insert (8) according to one of the preceding claims, characterized in that the plant section (31) has one or more incisions extending in the longitudinal direction (9).

6. Insert (8) according to one of the preceding claims, characterized in that it is made of a material that conducts heat well and conducts electricity well.

7. Use (8) according to one of the preceding claims, characterized in that the contact surface (32, 36, 37) for the elastic contact element (34, 35) extends in a direction transverse to the longitudinal direction (9).

8. Use (8) according to one of the preceding claims, characterized in that the elastic contact element (34, 35) is at least partially formed as a metal foil.

9. Insert (8) according to one of the preceding claims, characterized in that the elastic contact element (34, 35) is at least partially made of indium and / or has a doping of an electrically conductive material.

10. EUV radiation source (1) 10.

1. a source chamber (2) with 10.1.

1. a chamber wall having at least one chamber opening, 10.1.

2. an insert placed into the chamber opening (11), 10.

2. wherein the insert (8) is configured according to any one of claims 1 to 9.

11. EUV radiation source (1) according to claim 10, characterized in that an inner wall surrounding the chamber opening is adapted to the system section (31) of the insert (8).

12. Lighting system for a mask inspection system or a metrology system with an EUV radiation source (1) with an insert (8) according to one of claims 1 to 9.

13. Metrology system for inspecting a mask for EUV lithography with an illumination system according to claim 12.

14. Method for producing an EUV radiation source (1) comprising the following steps: 14.

1. Providing a source chamber (2) with a chamber wall into which an insert (8) according to one of claims 1 to 9 can be inserted, 14.

2. Providing an insert (8) according to any one of claims 1 to 9, 14.

3. Inserting the insert (11) into the chamber wall, 14.

4. wherein the insert (11) is deformed for or during insertion into the chamber wall.

15. Method according to claim 14, characterized in that the insert (8) and / or the elastic contact element (34, 35) is coated with a lubricant or a liquid metal before being inserted into the chamber wall.

Images