Insert for an external insert for an EUV radiation source

Abstract

An insert (bore) for an external insert (8) for an EUV radiation source (1) is made of a fiber-reinforced material.

Description

[0001] The invention relates to an insert (bore) for an outer insert (carrier) for an EUV radiation source. The invention also relates to an insert for an EUV radiation source with such an inner insert. Furthermore, the invention relates to an EUV radiation source with such an insert, as well as to an illumination system for a projection exposure system, a mask inspection system, or a metrology system with such an EUV radiation source, and to a projection exposure system and a metrology system with a corresponding illumination system. Finally, the invention relates to a method for producing an insert (bore) for an EUV radiation source.

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

[0003] EUV radiation sources are used in illumination 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 / 100856 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] Another plasma source is known from US 2006 / 0017387 A1.

[0006] One object of the invention is to improve an inner insert (bore) for an outer insert (carrier) for an EUV radiation source. This object is achieved by an insert according to the invention.

[0007] According to one aspect of the invention, the insert is made of a fiber-reinforced material.

[0008] This has been shown to have numerous benefits.

[0009] By using a fiber-reinforced material, the coefficient of thermal expansion could be significantly reduced. This reduced thermal stresses during operation, resulting in a lower likelihood of cracks forming during use.

[0010] In addition, production costs could be reduced considerably.

[0011] Furthermore, the strength of the insert could be increased.

[0012] Finally, the thermal conductivity of the insert was improved.

[0013] The inner insert is also called a bore insert. The outer insert, which is inserted into the wall of a source chamber of an EUV radiation source, is also called a carrier.

[0014] Together, the carrier and the inner insert (bore insert) are also called the bore.

[0015] The carrier may have a base body made of copper.

[0016] The bore insert can in particular be made of ceramic.

[0017] According to one aspect, the inner insert can be made at least partially of silicon carbide (SiC), graphite, or an isotropic SiSiC material. A corresponding SiSiC material is available, for example, under the trade name Cesic®. The material can, in particular, have diffusely arranged short fibers.

[0018] Short fibers are defined as fibers with a length of no more than 1 mm, in particular no more than 0.3 mm, and in particular no more than 0.1 mm. The proportion of such short fibers can, in particular, be at least 90%.

[0019] According to one aspect, the insert may be made of a material having a thermal expansion coefficient of at most 6 10 -6 / K, especially 4.5 · 10 -6 / K, especially 4 · 10 -6 / K, especially 3 · 10 -6 / K, especially 2 · 10 -6 / K in particular 1.5 · 10 -6 / K. This information may refer in particular to the fibers in the material.

[0020] According to a further aspect, the insert can comprise continuous carbon fibres. The fibres can in particular have a length of at least 1 cm, in particular at least 3 cm, in particular at least 5 cm. The proportion of fibres with such a minimum length can in particular be at least 50%, in particular at least 70%, in particular at least 90%. The proportion of short fibres, in particular fibres with a length of less than 3 cm, can in particular be at most 30%, in particular at most 20%, in particular at most 10%. According to a further aspect, so-called high-temperature carbon fibres can be used as fibres for the insert. This allows the thermal conductivity to be further improved. The thermal conductivity can be improved in particular in the fibre direction. By aligning the fibres in one or more specific directions, the heat dissipation and the strength of the insert can be specifically influenced.

[0021] This increases the strength of the insert and thus its service life.

[0022] According to a further aspect, the fibers of the insert can have a specific orientation. The fibers of the insert can, in particular, be arranged obliquely to the longitudinal direction. An oblique arrangement of the fibers is understood to mean an arrangement in which the fibers are neither parallel nor perpendicular to the longitudinal direction. The fibers can, in particular, be arranged at an angle in the range of 20° to 70° to the longitudinal direction.

[0023] The orientation of the fibers can be specifically specified during the insert's production. In particular, it is possible to use a wound tube or a fabric with appropriately oriented fibers to manufacture the insert.

[0024] According to a further aspect, the insert may have, in the longitudinal direction, successively an inner portion, a middle portion and an outer portion, wherein the middle portion has a smaller diameter than the inner portion and the outer portion.

[0025] The outer section may have a longitudinal extension that is at least 30%, in particular at least 50%, in particular at least 70%, in particular at least 100% of the longitudinal extension of the central section. This aspect may be independent of other aspects, in particular independent of the use of fiber-reinforced material for the bore. The aspects may also be combined with one another.

[0026] In particular, the sections may directly follow one another, in particular they may be adjacent to one another.

[0027] According to a further aspect, the insert can also be formed as a single piece. In this case, the central section and the outer section are formed as a single piece.

[0028] The inner section can also be formed separately from the middle section.

[0029] In this case, the term "section" is to be understood purely geometrically. A section does not necessarily have to be a separate component.

[0030] The different sections can, in particular, have different inner diameters. They can, in particular, be defined by their inner diameters. The middle section can have the smallest inner diameter.

[0031] The outer section may have an inner diameter that increases toward the outside. It may, in particular, be funnel-shaped.

[0032] In particular, the sections may have an identical outer diameter.

[0033] In particular, the sections may have an outer diameter that remains constant over their longitudinal extension.

[0034] A further object of the invention is to improve an external insert (carrier) for a source chamber of an EUV radiation source.

[0035] This object is achieved by an insert having an inner insert arranged in a passage channel according to the preceding description.

[0036] The advantages arise from those of internal use.

[0037] According to one aspect, the inner insert lies flat in the outer passage channel.

[0038] By using an inner insert according to the preceding description, an EUV radiation source, in particular an EUV xenon plasma source, an illumination system for a projection exposure system, a mask inspection system or a metrology system with such an EUV radiation source, a projection exposure system for EUV lithography and a metrology system for inspecting a mask for EUV lithography can be improved.

[0039] A further object of the invention is to improve a method for producing an insert for an EUV radiation source.

[0040] This task is solved by a procedure with the following steps: - Winding a tubular base body, - Impregnating the fibers with an adhesive that can completely carbonize, - Pyrolysis of the base body, - Infiltration of the base body with silicon or vapor deposition of the base body with silicon carbide (SIC) and - mechanical processing of the base body.

[0041] The base body can, in particular, be longer than the length of the insert to be produced. A plurality of such inserts can, in particular, be produced from the base body. The length of the base body can, in particular, be at least 10 cm, in particular at least 20 cm, in particular at least 30 cm, in particular at least 50 cm, in particular at least 1 m.

[0042] Phenolic resin in particular can be used as an adhesive.

[0043] The mechanical processing may, in particular, comprise dividing the base body into a plurality of parts. In this case, the base body is severed, in particular, perpendicular to the longitudinal direction.

[0044] For pyrolysis of the base body, it is heated to at least 700 °C, in particular at least 800 °C, in particular at least 900 °C.

[0045] Pyrolysis can be carried out in particular in the absence of oxygen.

[0046] To infiltrate the base body with silicon, the base body or parts of it can be heated with silicon granules in a chamber. This can melt the silicon. Alternatively or additionally, the base body can be vapor-coated with silicon carbide after pyrolysis. Chemical vapor deposition (CVD) can be used for this purpose. This can lead to improved insert strength. In particular, it can ensure that no uncrosslinked silicon is present in the base body material.

[0047] Excess silicon can then be removed from the base body. A mechanical process, such as sandblasting, can be used for this. Corundum, in particular, can be used as a blasting medium. This allows for the removal of excess silicon.

[0048] The inner insert (bore) can be produced from the base body produced and treated in this way by mechanical processing, for example a turning process.

[0049] The finishing process may include one or more cleaning steps.

[0050] Further features and details of the invention will become apparent from the description of exemplary embodiments based on the figures. They show: Fig. 1 a schematic cross-sectional drawing of an EUV radiation source, Fig. 2 a partially schematic sectional view through section II of a source chamber of the EUV radiation source in the area of ​​a passage channel, Fig. 3 a partially schematic sectional view through section II of a source chamber of the EUV radiation source in the region of a passage channel according to a variant, Fig. 4 schematically shows a longitudinal section through an insert (bore) for an outer insert (carrier) of a source chamber of an EUV radiation source, Fig. 5 schematically shows a mat for producing the insert according to Fig. 4 with fibers oriented in specific directions, Fig. 6 a mat according to Fig. 5 with alternative fiber orientations, Fig. 7 schematically shows a longitudinal section through an insert according to Fig. 4 with diffusely arranged short fibers and Fig. 8 schematically shows a view of the insert according to Fig. 7 in a developed state.

[0051] In Fig. 1 shows a schematic sectional drawing of an exemplary embodiment of an EUV radiation source 1. In Fig. 2 and Fig. Figure 3 shows a section of the same. The overall structure of the EUV radiation source 1 is merely exemplary and not limiting to Figure 5. In particular, the arrangement of the access / maintenance openings of the radiation source may differ from the illustrated design. The beam direction of the EUV radiation source 1 relative to the remaining optics and the installation direction of the insert in the source chamber wall are independent of each other and can also be reversed.

[0052] The EUV radiation source 1 is part of a not explicitly shown illumination system of a projection exposure system. For basic details, reference is made to DE 10 2017 212 352 A1, which is hereby fully incorporated into the present application.

[0053] 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 center plate 5 is located between the upper chamber part 3 and the lower chamber part 4. The center plate 5 forms a chamber wall of the source chamber 2, in particular of the upper chamber part 3.

[0054] In the following, the upper chamber part 3 is also referred to as the source chamber.

[0055] The center plate 5 has eccentric openings 6 and a central opening 7.

[0056] The center plate 5 can be constructed in several parts. In particular, it can comprise a plate 18 facing the source chamber 2, which can be subjected to high voltage, and a separate outer base plate 19.

[0057] 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 a "carrier." It has a first passage channel 10 extending in a longitudinal direction 9.

[0058] A second insert 11 is arranged in the first passage 10. The second insert 11 has a second passage 12 extending in the longitudinal direction 9. The carrier with the inner insert 11 is sometimes also referred to as a "bore."

[0059] 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.

[0060] During 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.

[0061] EUV radiation source 1 is an induction plasma current generator.

[0062] 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 system is, in particular, a component of an illumination system. The illumination system can, in particular, comprise one or more mirrors, in particular one or more facet mirrors. The illumination optics serve, in particular, to transfer the illumination radiation generated by the EUV radiation source 1 to a mask with structures to be imaged. The mask is also referred to as a reticle.

[0063] Also shown schematically is the Fig. 1 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, please refer to DE 10 2017 212 352 A1, in particular Fig. 23 and the associated description.

[0064] The maintenance area 14 can be sealed vacuum-tight from an external area 17 by means of a maintenance flap 16. The maintenance flap 16 can be opened for maintenance work. When the maintenance flap 16 is open, access to the maintenance area 14 and, through it, 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 the maintenance area 14, for example, to replace them.

[0065] In the following, with reference to the Fig. 2 and Fig. 3 describes details of the first, outer insert (carrier) 8 and, in particular, the second, inner insert (bore) 11. Corresponding designs of the inserts 8, 11 are advantageous regardless of the other structural details of the EUV radiation source 1.

[0066] The outer, first insert 8 is connected to the plate 18, for example, via several screws 30. In particular, it has an electrical contact 21 to the plate 18. An O-ring can be provided in the connection area between the first insert 8 and the plate 18.

[0067] The first insert 8 is connected to the base plate 19, for example, via a plurality of screws 30. In particular, it has an electrical contact 23 to the base plate 19. An O-ring can be provided in the contact area between the first insert 8 and the base plate 19.

[0068] 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 essentially no play. However, it can be arranged so as to be displaceable in the longitudinal direction within the first passage channel 10.

[0069] The inner insert 11 can be thermally shrunk into the passage channel 10. The inner insert 11 can also be soldered, welded, or glued to the passage channel 10. In particular, it can be connected to the passage channel 10 in a form-fitting and / or material-fitting manner.

[0070] In the Fig. 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 Fig. 3, it also has an outer section 28. The sections 26, 27, 28 follow one another in the longitudinal direction 9. In particular, they can be adjacent to one another in the longitudinal direction 9.

[0071] The inner section 26, the middle section 27 and the outer section 28 can have substantially constant outer diameters over their extension in the longitudinal direction 9. In particular, they can have identical outer diameters. The outer section 28 can, as in Fig. 2 are omitted.

[0072] The inner section 26 is sleeve-shaped. It is, in particular, essentially hollow-cylindrical. However, it may have chamfered ends.

[0073] The middle section 27 has a smaller inner diameter dm than the inner section 26 with inner diameter di, dm < di.

[0074] In the following, with reference to the Fig. 4 to 8 describe exemplary different variants of the inner insert 11.

[0075] In the Fig. In the variant of the inner insert 11 schematically illustrated in Figure 1, the insert 11 is made of a wound tube or fabric 31. It has successive layers 32 with fibers 33 of different orientations.

[0076] In the Fig. 5 and Fig. 6, different orientations of the fibers 33 in two successive layers 32 in a wound state of the insert 11 are shown as examples.

[0077] The fibers 33 are particularly oriented obliquely to the longitudinal direction 9. The fibers 33 are particularly arranged at angles in the range of 20° to 70° to the longitudinal direction 9. This resulted in particularly uniform wear behavior.

[0078] The geometry of the insert 11 is in the Fig. 4 and Fig. 7 is shown merely as an example. It is not to be understood as limiting. The insert 11 may, in particular, have a different geometry, at least in sections.

[0079] According to the Fig. 7 and Fig. In the variant shown in Figure 8, the material for insert 11 has diffusely arranged short fibers.

[0080] In the following, a method for producing the insert 11 is described as an example.

[0081] To produce the insert 11, a base body can first be wound.

[0082] Continuous fibers can be used for the base body. Fabric mats can also be used.

[0083] A CNC winding machine can be used to wind the base body.

[0084] The fibers are preferably impregnated with an adhesive that can completely carbonize.

[0085] The base body can be considerably longer than the length of the insert 11 to be manufactured. The base body can, in particular, have a length in the order of 1 m. Preferably, several inserts 11 can be manufactured from the base body.

[0086] The base body is then pyrolyzed.

[0087] To pyrolyze the base material, it is heated in an oven to approximately 1000 °C. This allows the adhesive to be converted into pure carbon.

[0088] The method may then include mechanical processing of the base body. This mechanical processing may also be performed later if necessary. The base body may, in particular, be divided into a plurality of shorter sections.

[0089] The base body or the parts can then be infiltrated with silicon.

[0090] For silicon infiltration, the components are placed in a furnace with silicon granules. There, the silicon is liquefied by heating, allowing it to be embedded into the base body or the components.

[0091] The excess silicon is then removed from the components. This may involve mechanical processing, particularly sandblasting.

[0092] Finally, a final mechanical processing and cleaning process takes place. The component is turned to its final dimensions.

[0093] The description of the manufacturing process is not restrictive, but purely exemplary. Deviations and / or modifications to the process are possible.

Claims

[1] Use (11) for an external use (8) for an EUV radiation source (1) 1.

1. with an inner passage channel (12) extending in a longitudinal direction (9), 1.

2. characterized by , that the insert (11) is made of a fiber-reinforced material. [2] Use (11) according to claim 1, characterized by that it is at least partially made of silicon carbide (SiC), graphite or an isotropic SiSiC material. [3] Use (11) according to any of the preceding claims, characterized by , that the insert (11) is made of a material with a coefficient of thermal expansion of at most 6×10 -6 / K is manufactured. [4] Use (11) according to any of the preceding claims, characterized by that it has continuous carbon fibers. [5] Use (11) according to any of the preceding claims, characterized by that it contains high-temperature carbon fibers. [6] Use (11) according to any of the preceding claims, characterized by , that the material of the insert (11) has fibers with an orientation oblique to the longitudinal direction (9). [7] Use (11) according to any of the preceding claims, characterized by , that it has an inner section (26), a middle section (27) and an outer section (28) successively in the longitudinal direction (9), 7.

1. wherein the middle section (27) has a smaller inner diameter (d m ) exhibits as the inner section (26) and the outer section (28), and 7.

2. wherein the outer section (28) has an extension (l a ) in the longitudinal direction, which has at least 30% of an extent (l m ) of the middle section (27) in the longitudinal direction (9). [8] Use (11) according to any of the preceding claims, characterized by that it is trained in one piece. [9] Use (8) for an EUV radiation source (1) with 9.1 an outer passage channel (10) extending in a longitudinal direction (9) and 9.

2. an inner insert (11) arranged in the outer passage channel (10) according to one of the preceding claims. [10] Use (8) according to claim 9, characterized by , that the inner insert (11) lies flat in the outer passage channel (10). [11] having an EUV radiation source (1) 11.

1. a source chamber (2) with 11.1.

1. a chamber wall (5) having at least one chamber opening (7), 11.1.

2. a first insert (8) inserted into the chamber opening (7) with an outer passage channel (10) extending in a longitudinal direction (9) and 11.1.

3. an inner insert (11) arranged in the outer passage channel (10) with an inner passage channel (12) extending in the longitudinal direction (9), 11.

2. characterized by, that the inner insert (11) is designed according to one of claims 1 to 8. [12] Lighting system for a projection exposure system, a mask inspection system or a metrology system comprising an EUV radiation source (1) with an insert (8) according to claim 11. [13] Projection exposure system for EUV lithography comprising 13.

1. a lighting system according to claim 12 for illuminating a reticle arranged in an object field and 13.

2. a projection optic for imaging the reticulum onto a wafer arranged in an image field. [14] Metrology system for inspecting a mask for EUV lithography with an illumination system according to claim 12. [15] Method for manufacturing an insert (11) for an EUV radiation source (1) comprising the following steps: 15.

1. Winding a tubular base body from a fibrous material, 15.

2. Impregnating the fibers with an adhesive that can fully carbonize, 15.

3. Pyrolysis of the parent material, 15.

4. Infiltration of the base body with silicon or vapor deposition of the base body with silicon carbide (SiC), 15.

5. Machining of the base body.

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