Object holder and method for manufacturing object holder

Abstract

An object holder configured to support an object, the object holder comprising: a base body formed from a plate having an upper side and a contact surface on the upper side of the plate, the contact surface having a predetermined flatness for contacting the object, where a notched absorbing layer is provided on the upper side of the plate, the notched absorbing layer having a low volume density, the notched absorbing layer having a predetermined flatness for contacting the object; the present invention relates to a method for manufacturing a notch absorbing layer on a substrate such that the notch absorbing layer can be compressed by compaction in a layer volume without compromising the flatness of a contact surface under the mechanical action of foreign particles, a multi-layer laminate comprising a notch absorbing layer and a top layer arranged on the notch absorbing layer being arranged on an upper side of the substrate, wherein at least one of the notched absorber layer and the top layer includes at least one of boron and carbon.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to EP application 23153911.5 filed on January 30, 2023, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present invention relates to an object holder configured to support an object and a method for manufacturing such an object holder. In particular, the present invention relates to a wafer holder or mask holder or wafer chuck or mask chuck for holding a semiconductor wafer or photolithography mask during processing of the semiconductor wafer or photolithography mask, and a method for manufacturing the same. The present invention finds application in the processing of objects, particularly semiconductor wafers. Background Art

[0004] A lithographic apparatus is a machine configured to apply a desired pattern to a substrate. A lithographic apparatus can be used, for example, in the manufacture of integrated circuits (ICs). A lithographic apparatus can, for example, project a pattern from a patterning device (e.g., a mask) onto a layer of radiation-sensitive material (resist) disposed on a substrate.

[0005] To project patterns onto substrates, lithographic equipment uses electromagnetic radiation. The wavelength of this radiation determines the minimum size of features that can be formed on the substrate. Compared to lithographic equipment using radiation with a wavelength of, for example, 193 nm, lithographic equipment using extreme ultraviolet (EUV) radiation with a wavelength in the 4-20 nm range, such as 6.7 nm or 13.5 nm, can be used to form smaller features on substrates.

[0006] As is known, in photolithographic semiconductor processing (chip production), object holders are used to hold disc-shaped or plate-shaped objects, such as semiconductor wafers, in particular silicon wafers. Depending on the holding force applied, a distinction is made between electrostatic object holders, which hold the object electrostatically, and vacuum object holders, which hold the object under negative pressure.

[0007] Typically, for example, an electrostatic object holder has a base with several plate-shaped or layered elements, at least one of which is equipped with an electrode arrangement that generates the electrostatic holding force. At least one of the plate-shaped elements is made of a mechanically rigid ceramic to fulfill both load-bearing and cooling functions. Furthermore, the electrostatic object holder typically has at least one exposed surface, for example on its upper side, formed by a plurality of protruding studs. The end faces of the studs form the contact surface for the object to be held.

[0008] For use in chip production, the contact surface spanned by the pillars must be as flat as possible, as inhomogeneities can lead to bowing of the held semiconductor wafer and, therefore, errors in its structure during chip production. Local inhomogeneities of a few nanometers, such as protruding pillars >10 nm, can already lead to intolerable bowing of the semiconductor wafer.

[0009] The flatness of the contact surface spanned by the end faces of the posts can be compromised by notches on the surface of the object holder. Notches can be caused by mechanical influences, such as, for example, foreign particles (notch damage). For example, when a semiconductor wafer is pressed against the contact surface during processing, sharp or pointed particles adhering to the back side of the semiconductor wafer can create notches in the end faces of the posts.

[0010] The notch that acts locally as a depression in the end face does not actually directly damage the flatness of the contact surface. However, near the notch, local accumulation or protrusion occurs due to material displacement caused by penetrating foreign particles, which damages the flatness.

[0011] Notch damage limits the service life of the object holder. Object holder regeneration results in high costs due to downtime and object holder handling. Therefore, minimizing notch damage is of interest. Summary of the Invention

[0012] According to a first aspect of the present invention, there is provided an object holder configured to support an object, the object holder comprising: a base body formed by a plate having an upper side and a contact surface having a predetermined flatness on the upper side of the plate for contacting the object; wherein a notch absorbing layer is provided on the upper side of the plate, the notch absorbing layer having such a low volume density that, under the mechanical action of foreign particles, the notch absorbing layer can be compressed by compaction in the layer volume without impairing the flatness of the contact surface; wherein a multilayer laminate is provided on the upper side of the plate, the multilayer laminate comprising a notch absorbing layer and a top layer arranged on the notch absorbing layer; wherein at least one of the notch absorbing layer and the top layer comprises at least one of boron and carbon.

[0013] Advantages may include reduced wear on the top layer of the object holder while maintaining low friction. This may mean that the object holder can be used longer without having to replace or repair parts. Consequently, downtime of the lithographic apparatus may be reduced. Advantages may also include that the object holder has reduced susceptibility to notch damage, has an extended service life, can be manufactured and used at reduced cost, and / or has a reduced tendency to mechanical stress due to impurities (such as, for example, particles).

[0014] The volume density of the notch absorbent layer may be less than the volume density of the solid material of the notch absorbent layer.The volume density of the groove absorbent layer may be selected.

[0015] The bulk density of the notched absorbent layer may be in the range of 90% to 10%, preferably in the range of 85% to 10%, even more preferably in the range of 85% to 50% of the bulk density of the solid material of the notched absorbent layer.

[0016] The top layer may have a greater bulk density than the notch absorbent layer.

[0017] The volume density of the notched absorbent layer may be in the range of 90% to 10%, preferably in the range of 85% to 10%, even more preferably in the range of 85% to 50% of the volume density of the top layer.

[0018] The top layer may have a greater hardness than the notch absorbing layer.

[0019] The top layer and the groove absorbent layer may be formed from the same material.

[0020] At least one of the notch absorbing layer and the top layer may include diamond.

[0021] The notch absorbing layer and the top layer may comprise diamond.

[0022] At least one of the notch absorber layer and the top layer may include at least one of graphene, boron nitride, carbon nitride, and boron carbon nitride.

[0023] At least one of the notch absorber layer and the top layer may include at least one of the following: B, B4C, BC2, BC3, C, C3N4, N, BN, B 2.5 N, BCN, BC2N, BC4N.

[0024] The notch absorber layer may include at least one of CrN, a metal, a ceramic including a nitride, and a ceramic including a carbide.

[0025] The top layer may include at least one of boron or carbon. The top layer may include boron. The top layer may include carbon. The top layer may include diamond.

[0026] The notched absorbent layer may be a porous and / or fibrous layer.

[0027] The notch absorber layer may have nano-sized or ultra-nano-sized porosity.

[0028] The multilayer laminate may include a substrate layer disposed between the plate and the notch absorbent layer.

[0029] The base layer may have a greater bulk density than the notch absorbent layer.

[0030] The base layer may have a greater hardness than the notch absorbing layer.

[0031] The base layer and the groove absorbent layer and / or the top layer are formed from the same material.

[0032] The contact surface may be formed by a plurality of protruding studs or burls arranged on the upper side of the plate. According to a second aspect of the present invention, there is provided an object holder (100) configured to support an object, the object holder comprising: a base (16), a plurality of burls on the base, the plurality of burls forming a contact surface (19) having a predetermined flatness for contacting the object, wherein each of the plurality of burls comprises a multilayer laminate (20), the multilayer laminate (20) comprising a notch absorbing layer (21) and a top layer (22) arranged on the notch absorbing layer (21), wherein the notch absorbing layer (21) has such a low volume density that, in the event of a mechanical action of a foreign particle (15), the notch absorbing layer (21) can be compressed by compaction in the layer volume without impairing the flatness of the contact surface (19), wherein at least one of the notch absorbing layer (21) and the top layer (22) comprises at least one of boron and carbon.

[0033] According to a third aspect of the present invention, there is provided a lithographic apparatus comprising an object holder as described above.

[0034] According to a fourth aspect of the present invention, a method for manufacturing an object holder is provided, which is suitable for holding an object, the method comprising the following steps: providing a substrate formed by a plate having an upper side, wherein the contact surface on the upper side of the plate has a predetermined flatness for contacting the object; forming a notch absorbing layer on the upper side of the plate, wherein the notch absorbing layer has such a low volume density that, under the mechanical action of foreign particles, the notch absorbing layer can be compressed by compaction in the layer volume without impairing the flatness of the contact surface; depositing a multilayer laminate on the upper side of the plate, wherein the multilayer laminate comprises the notch absorbing layer and a top layer arranged on the notch absorbing layer; wherein at least one of the notch absorbing layer and the top layer comprises at least one of boron and carbon.

[0035] The multi-layer laminate may include a substrate layer disposed between the panel and the notch absorbent layer.

[0036] At least one of the notch absorption layer, the top layer and the base layer may be formed by chemical vapor deposition, preferably linear antenna microwave chemical vapor deposition.

[0037] The top layer and / or the base layer may be formed of the same material as the notch absorber layer, and during deposition of the multilayer laminate, deposition process parameters may be altered in such a manner that the notch absorber layer is formed to have a lower bulk density than the top layer and / or the base layer. The top layer and / or the base layer may be formed of the same material as the notch absorber layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings, in which:

[0039] Figure 1 A lithographic system comprising a lithographic apparatus and a radiation source is shown;

[0040] Figure 2 A schematic diagram of an object holder according to an embodiment of the present invention is shown;

[0041] Figure 3 A schematic diagram showing an object holder according to another embodiment of the present invention is shown. DETAILED DESCRIPTION

[0042] Figure 1 A lithographic system is shown comprising a radiation source SO and a lithographic apparatus LA. The radiation source SO is configured to generate an EUV radiation beam B and provide the EUV radiation beam B to the lithographic apparatus LA. The lithographic apparatus LA comprises an illumination system IL, a support structure MT configured to support a patterning device MA (e.g., a mask), a projection system PS, and a substrate table WT configured to support a substrate W (e.g., a semiconductor wafer).

[0043] The illumination system IL is configured to condition the EUV radiation beam B before it is incident on the patterning device MA. Furthermore, the illumination system IL may include a faceted field mirror arrangement 10 and a faceted pupil mirror 11. The faceted field mirror arrangement 10 and the faceted pupil mirror 11 together provide the EUV radiation beam B with a desired cross-sectional shape and a desired intensity distribution. The illumination system IL may include other mirrors or arrangements in addition to or instead of the faceted field mirror arrangement 10 and the faceted pupil mirror 11.

[0044] After being so conditioned, the EUV radiation beam B interacts with the patterning device MA. As a result of this interaction, a patterned EUV radiation beam B' is produced. The projection system PS is configured to project the patterned EUV radiation beam B' onto the substrate W. For this purpose, the projection system PS may comprise a plurality of mirrors 13, 14 configured to project the patterned EUV radiation beam B' onto the substrate W held by the substrate table WT. The projection system PS may apply a reduction factor to the patterned EUV radiation beam B' so as to form an image having features that are smaller than corresponding features on the patterning device MA. For example, a reduction factor of 4 or 8 may be applied. Although in Figure 1 The projection system PS is shown with only two mirrors 13, 14, but the projection system PS may comprise a different number of mirrors (eg six or eight mirrors).

[0045] The substrate W may include a previously formed pattern. In this case, the lithographic apparatus LA aligns the image formed by the patterned EUV radiation beam B′ with the pattern previously formed on the substrate W.

[0046] A relative vacuum, ie a small amount of gas (eg hydrogen) at a pressure well below atmospheric pressure, may be provided in the radiation source SO, in the illumination system IL and / or in the projection system PS.

[0047] For example, Figure 1 The radiation source SO shown is of a type that may be referred to as a laser produced plasma (LPP) source. A laser system 1, which may, for example, comprise a CO2 laser, is arranged to deposit energy via a laser beam 2 into a fuel, such as tin (Sn), provided from, for example, a fuel emitter 3. Although tin is mentioned in the following description, any suitable fuel may be used. The fuel may, for example, be in liquid form and may, for example, be a metal or alloy. The fuel emitter 3 may comprise a nozzle configured to direct tin, for example in the form of droplets, along a trajectory toward a plasma formation region 4. The laser beam 2 is incident on the tin at the plasma formation region 4. Deposition of laser energy into the tin generates a tin plasma 7 at the plasma formation region 4. Radiation, including EUV radiation, is emitted from the plasma 7 during deexcitation and recombination of electrons and ions of the plasma.

[0048] EUV radiation from the plasma is collected and focused by a collector 5. The collector 5 comprises, for example, a near-normal incidence radiation collector 5 (sometimes more generally referred to as a normal incidence radiation collector). The collector 5 may have a multilayer mirror structure arranged to reflect EUV radiation (e.g., EUV radiation having a desired wavelength, such as 13.5 nm). The collector 5 may have an elliptical configuration with two focal points. The first focal point may be at the plasma formation region 4, and the second focal point may be at an intermediate focus 6, as described below.

[0049] The laser system 1 may be spatially separated from the radiation source SO. In this case, the laser beam 2 may be delivered from the laser system 1 to the radiation source SO by means of a beam delivery system (not shown) comprising, for example, suitable directing mirrors and / or beam expanders and / or other optical devices. The laser system 1, the radiation source SO and the beam delivery system may together be considered a radiation system.

[0050] The radiation reflected by the collector 5 forms an EUV radiation beam B. The EUV radiation beam B is focused at an intermediate focus 6 to form an image at the intermediate focus 6 of a plasma present in the plasma formation region 4. The image at the intermediate focus 6 serves as a virtual radiation source for the illumination system IL. The radiation source SO is arranged so that the intermediate focus 6 is located at or near an opening 8 in an enclosure 9 of the radiation source SO.

[0051] although Figure 1 The radiation source SO is depicted as a laser produced plasma (LPP) source, but any suitable source may be used to generate EUV radiation, such as a discharge produced plasma (DPP) source or a free electron laser (FEL).

[0052] although Figure 1 An EUV system with mirrors is shown, but it should be understood that in some embodiments other lithography systems may be used, such as a DUV with lenses.

[0053] Figure 2 In the lower part, a holding device 100 or an object holder for holding, for example, a semiconductor wafer W (i.e. a structural component or an object) is schematically shown, which holding device or object holder has a base 16 with a plate 17 and a plurality of columns 18 in a manner known per se. The columns can also be called burls. The end faces of the columns 18 protruding in the z direction span a contact surface 19 of the holding device 100 for accommodating the semiconductor wafer W. The contact surface 19 has a predetermined flatness for contacting the semiconductor wafer W. The side of the plate 17 on which the semiconductor wafer W is placed is the upper side of the plate 17. For example, the plate 17 is made of a SiSiC glass composition, while the columns 18 are made of glass or ceramic. In some embodiments, the columns can be formed of electrically conductive SiSiC (on a SiSiC plate), while in other embodiments the columns can be formed of glass on a plate formed of electrodes sandwiched between glass layers. It is emphasized that Figure 2 is a schematic diagram. In a practical example, the pillars have a height of, for example, 10 μm, a width of 220 μm and a pitch of 1.5 mm. Figure 2 The middle portion of the diagram schematically shows a post 18 in an enlarged manner. In other embodiments, the holding device may not include a post. The contact surface may be in contact with the structural component over the entire surface.

[0054] The holding device 100 may be, for example, an electrostatic holding device (also known as an electrostatic wafer plate, an electrostatic clamp, an electrostatic clamp, an ESC, or an electrostatic chuck) or a vacuum holding device (also known as a vacuum clamp or a vacuum chuck). The holding device 100 may form at least a portion of a support structure MT configured to support a patterning device MA (e.g., a mask or a photolithography mask). The holding device 100 may form at least a portion of a substrate table WT configured to support a substrate W (e.g., a semiconductor wafer).

[0055] The spatial direction parallel to the contact surface 19 of the holding device 100 is referred to as the lateral direction, and the direction perpendicular thereto is referred to as the thickness direction (z direction). In the lateral direction, the base 16 preferably has a planar extent parallel to the contact surface 19, and can be formed by one or more plates 17 stacked and bonded to each other in the thickness direction. The upper side of the base 16 is the side used to contact and hold a structural component (e.g., a semiconductor wafer W).

[0056] A multilayer laminate 20 is provided above the columns 18. In the multilayer laminate 20, a notch-absorbing layer 21 is arranged in each case at the upper end of the columns 18. A top layer 22 is located above the notch-absorbing layer 21, so that in the depicted example the top layer 22 is the uppermost layer, so that the end face and the entire contact surface 19 are spanned by all layer portions of the top layer 22 on the columns 18. In other examples, the notch-absorbing layer 21 may be the uppermost layer, so that the end face and the entire contact surface 19 are spanned by all layer portions of the notch-absorbing layer 21 on the columns 18 (i.e. there is no top layer 22). Figure 2 In some embodiments, the multi-layer laminate 20 is deposited on the upper side of the pillars 18, while in other embodiments, the pillars 18 may be formed from the multi-layer laminate 20.

[0057] In the structure of the base body 16, the notch absorbing layer 21 (and the top layer 22) is preferably a flat layer that extends parallel to the contact surface 19, preferably over the entire extent of the contact surface 19. The notch absorbing layer 21 (and the top layer 22) can be a continuous layer or can include a plurality of layer portions that are limited to the lateral extent of the column 18, in particular to the extent of the end faces of the column 18. When the holding device 100 is adapted to contact and hold a structural component on both sides, each side forms the upper side, in which case the notch absorbing layer 21 (and the top layer 22) is preferably provided on both sides.

[0058] exist Figure 2 , the notch absorbing layer 21 and its function are further enlarged. The notch absorbing layer 21 is composed of a porous material, such as diamond, for example. When the semiconductor wafer W is placed in place, if there are foreign particles 15 (not shown) on the contact surface of the semiconductor wafer W or on the surface of the top layer 22, the foreign particles 15 can be squeezed through the top layer 22 and into the notch absorbing layer 21. This results in a depression 21A, which is not critical for maintaining the functionality of the device 100, in particular for the planar contact of the semiconductor wafer W. In the vicinity of the depression 21A, the material of the notch absorbing layer 21 is compressed by the pressed-in foreign particles 15, thereby avoiding upward protrusions and not impairing the upward flatness of the contact surface 19. The foreign particles 15 can remain adhered to the notch absorbing layer 21, can remain adhered to the back side of the wafer, or can be removed by cleaning the surface.

[0059] The term "foreign particles" refers to any impurities (foreign matter or defects) that may arise between the contact surface and the structural component to be retained during use of the retaining device 100. Impurities may include, for example, particles having rounded or angular shapes, dense or elongated forms, fibers, and / or combinations of several particles and / or fibers. Impurities may be formed, for example, from the material of the structural component to be retained, the material of the retaining device 100, and / or materials from the environment. The notch-absorbing layer 21 is adapted to at least partially accommodate (absorb) the volume of foreign particles 15, in particular protruding defects on the rear side of the structural component.

[0060] The structure of the notch absorber layer 21 preferably includes cavities and spaces between the atomic components of the material of the notch absorber layer 21, resulting in a reduced bulk density, and optionally, hardness, of the notch absorber layer 21 compared to a material without microscopic gaps. Consequently, foreign particles 15 pressing against the contact surface of the substrate 17 with a force component in the thickness direction can locally displace and compress the atomic components of the material of the notch absorber layer 21. The material within the layer volume of the notch absorber layer 21 is compacted and locally compressed near the foreign particles 15. Bulk density may also be referred to as body density, apparent density, or bulk density.

[0061] It has been found that compaction occurs primarily in the lateral and / or thickness directions to the depth of the notch-absorbing layer 21, while localized accumulation near the foreign particles 15 throughout the thickness of the notch-absorbing layer 21 is eliminated or minimized to a negligible level. Advantageously, compression of the notch-absorbing layer 21 does not impair the flatness of the contact surface 19. Thus, the notch-absorbing layer 21 is advantageously distinguished from conventional impact-absorbing layers having encapsulated surface protrusions.

[0062] Another advantage of the present invention is that the notch absorbing layer 21 can reduce susceptibility to notch damage by absorbing the bulk of foreign particles 15. Since flatness is not compromised by foreign particles 15, especially during use of the holding device 100, the notch absorbing layer 21 provides an extended service life for the holding device. Finally, mechanical stress caused by particles is prevented or reduced to negligible levels.

[0063] The term "flatness" refers to the shape tolerance within which the flat contact surface 19 of the holding device 100 lies, whereby the tolerance limit is formed by two surfaces parallel to the ideally produced contact surface 19. Flatness is compromised if the actual contact surface produced protrudes through one of these parallel surfaces, in particular through the upper surface facing away from the holding device. The tolerance limit is determined as a function of the specific use of the holding device, in particular the required processing accuracy, the elasticity of the structural component to be held, and the elasticity of the column.

[0064] While localized impairments of flatness deep in the material (i.e., toward the base 16) are not critical for the contact function of the contact surface 19 and can be tolerated, localized impairments of flatness beyond the level of the contact surface 19 (i.e., away from the base 16) are a problem because they interfere with the flatness of the structural component being maintained. The flatness is maintained by the recessed absorbing layer 21, particularly on the contact surface 19, by avoiding upward projections (bumps, accumulations, or ridges) within specified tolerances.

[0065] The notch absorbent layer 21 may be a porous and / or fibrous layer. The top layer 22 has a greater hardness than the notch absorbent layer 21. Typically, in particular when made of the same material, the top layer 22 has a greater bulk density than the notch absorbent layer 21. The bulk density of the notch absorbent layer 21 may be selected in the range of 90% to 10%, preferably in the range of 85% to 10%, even more preferably in the range of 85% to 50% of the bulk density of the top layer 22. However, it should be understood that in some embodiments, the bulk density of the top layer may be less than the bulk density of the notch absorbent layer, i.e., when they are different materials. For example, the notch absorbent layer may be 5.9 g / cm 3 80% porous CrN, the top layer can be 3.5g / cm 3 In this example, the top layer is still harder than the notch absorbing layer.

[0066] The volume density of the notch absorbent layer 21 is less than the volume density of the solid material of the notch absorbent layer 21. The porosity and / or fiber density can be adjusted in such a way that the volume density of the notch absorbent layer 21 is selected to be in the range of 90% to 10%, particularly in the range of 85% to 10%, for example, in the range of 85% to 50%, of the volume density of the solid material of the notch absorbent layer 21. Here, the term "solid material" refers to a single crystal having the same chemical composition and crystal structure as the notch absorbent layer, or, if the material of the notch absorbent layer 21 does not form a single crystal and / or no reliable data exists, a theoretically defect-free material having the same composition and atomic structure as the notch absorbent layer 21.

[0067] Figure 3 Another embodiment is shown. Figure 2In contrast to the multilayer laminate 20, which is merely a double-layer laminate, the multilayer laminate 20 may further include a base layer 23. The base layer 23 is disposed between the panel 17 and the notch-absorbing layer 21. In this embodiment, the notch-absorbing layer 21 is embedded between the top layer 22 and the base layer 23. The base layer 23 may be referred to as an adhesive layer. Typically, the base layer 23 has a greater bulk density than the notch-absorbing layer 21, particularly when made of the same material. The base layer 23 may have the same bulk density as the top layer 22, particularly when made of the same material. The base layer 23 has a greater hardness than the notch-absorbing layer 21.

[0068] Unlike the illustration, the multilayer laminate 20 may include more than three layers. These layers may be formed of the same material or different materials. In particular, in embodiments where a column is formed from the multilayer laminate 20, it may be advantageous to form the multilayer laminate 20 with more and / or thicker layers in order to achieve a desired column height.

[0069] In a first example, the layers in the multilayer laminate 20 include a notch absorbing layer 21 made of porous diamond having a predetermined thickness and a top layer 22 made of diamond having a predetermined thickness. In a second example, the base layer 23 is made of diamond having a predetermined thickness, the notch absorbing layer 21 is made of porous diamond having a predetermined thickness, and the top layer 22 is made of diamond having a predetermined thickness. Because the top layer 22 is made of diamond, it has a greater hardness than the CrN top layer, as is known from conventional holding devices. The hardness of the base layer 23 can be selected to be equal to or greater than the hardness of the top layer 22. The notch absorbing layer 21 has the lowest hardness due to its porosity. In some embodiments, the top layer 22 can be thinner than the notch absorbing layer 21. In some embodiments, the base layer 23 can be thicker than the top layer 22 and / or the notch absorbing layer 21. When CrN is used as the material for the notch absorbing layer, a typical thickness can be 3 μm or 4 μm.

[0070] Layers 21, 22 and 23 are produced by chemical vapor deposition, for example linear antenna microwave chemical vapor deposition. For example, the hardness difference between the layers can be adjusted by changing the gas composition. For example, CH4 / CO2 / H2 can be used, and changing the respective ratios of these gases allows different levels of porosity to be achieved in the layers. For example, a higher CO2 content (e.g., 80%) can lead to the formation of dendritic forms (diamond). Other deposition conditions, such as temperature and / or pressure, can also be changed to adjust the properties of the material (such as thickness, morphology and crystalline quality). By this method of changing the gas composition used for chemical vapor deposition, the deposited layer becomes more porous and / or has fibrous structures in its microstructure. Layers 21, 22, and 23 may be formed using the materials described in the paper "Great Variety of Man-Made Porous Diamond Structures: Pulsed Microwave Cold Plasma System with a Linear Antenna Arrangement"; ACS Omega 2019 4(5), 8441-8450; DOI: 10.1021 / acsomega.9b00323; https: / / pubs.acs.org / doi / 10.1021 / acsomega.9b00323 It will be appreciated that other methods may be used.

[0071] It has been shown that linear antenna microwave chemical vapor deposition can produce dense and porous coatings. By applying appropriate plasma conditions, dense and porous (dendritic) diamond structures can be produced. This allows the deposition of two-layer or three-layer stacks with the following properties. The porous notch absorption layer 21 provides the possibility of compression and absorption volume in the case of a depression, so that the force of the depression is not transferred to the substrate (e.g., plate 17 and / or pillar 18). In addition, accumulation near the depression is prevented, resulting in an uneven surface. The top layer 22 defines the performance with respect to friction and wear (e.g., using a very hard substance, such as diamond, provides reduced wear during use compared to using a softer substance, such as CrN). In the case of a three-layer stack, the dense and hard base layer 23 protects the substrate (e.g., plate and / or pillar). That is, the base layer 23 prevents cracks and / or depressions from being transferred to the substrate (e.g., plate 17 and / or pillar 18).

[0072] The density and structure of the notch absorber layer 21 can be optimized to provide the volume required to accommodate the particles. The hardness can also be optimized so that the buffer zone (i.e., the notch absorber layer 21) breaks before the underlying substrate (e.g., plate 17 and / or pillar 18) is damaged. The hardness of the notch absorber layer 21 can be equal to or lower than the underlying substrate (e.g., plate 17 and / or pillar 18, such as the base material of pillar 18). Since the deposition of diamond is possible even below the melting point of glass, the concept can be used to produce, for example, diamond-coated electrostatic clamps with glass electrodes. Previously, coatings, such as top layers, may have been limited to being applied by sputter coating, and therefore very hard coatings such as diamond could not be applied. However, using, for example, linear antenna microwave chemical vapor deposition allows the use of diamonds with the properties described to be applied.

[0073] For example, the top layer 22 can be microcrystalline or nanocrystalline diamond. The notch absorber layer 21 can be dendritic diamond. If a base layer 23 is present, the base layer 23 can be microcrystalline, nanocrystalline, or ultra-nanocrystalline diamond. More generally, the notch absorber layer 21 can have nano- or ultra-nano-sized porosity. The top layer 22 and / or base layer 23 can be hard and non-porous.

[0074] Multilayer laminates 20, for example, having two or three layers, can advantageously exhibit reduced convexity and / or lack cracks when compared to conventional retaining devices having a single CrN top layer. Flatness can be substantially less compromised by the absorption effect of notch absorbing layer 21, and particles can be effectively absorbed by notch absorbing layer 21. Furthermore, using diamond as the top layer reduces wear while maintaining low friction. This is because CrN is less hard than diamond, resulting in relatively high wear.

[0075] It should be understood that in other embodiments, one or more of the layers 21, 22, 23 may be formed from materials other than diamond. The layers 21, 22, 23 (e.g., the top layer 22) may include a very hard or superhard material (e.g., a material having a hardness value exceeding 40 gigapascals (GPa)). Typically, one or more of the layers 21, 22, 23 may include at least one of boron and carbon (e.g., the top layer 22 may include boron or carbon). In embodiments, the top layer, the notch absorbing layer, and / or the base layer may include boron and / or carbon. As an example, the top layer 22 may include at least one of the following: graphene, boron nitride, carbon nitride, and boron carbon nitride. More specifically, the top layer 22 may include at least one of the following: B, B4C, BC2, BC3, C, C3N4, N, BN, B 2.5 N, BCN, BC2N, BC4N (ie, a stable BCN phase). In an embodiment, base layer 23 and top layer 22 may be formed of the same material (eg, base layer 23 may be formed of any of the materials described above with respect to top layer 22).

[0076] In an embodiment, the notch absorption layer 21 may include at least one of the following: B, B4C, BC2, BC3, C, C3N4, N, BN, B 2.5 N, BCN, BC2N, BC4N; metal (i.e., any metal); ceramics including nitrides and ceramics including carbides. In an embodiment, the top layer 22 and the notch absorber layer 21 may be formed of the same material. In an embodiment, the base layer 23 and the notch absorber layer 21 may be formed of the same material (e.g., the base layer 23 may be formed of any of the materials described above with respect to the notch absorber layer 21). In an embodiment, the top layer 22 and the notch absorber layer 21 may be formed of the same material (e.g., the top layer 22 may be formed of any of the materials described above with respect to the notch absorber layer 21, and vice versa).

[0077] In other examples, one or more of layers 21, 22, 23 (e.g., the notch absorption layer 21) can be manufactured by another method (e.g., reactive magnetron sputtering). In this case, the hardness difference between the layers is adjusted by the partial pressure ( / gas flow) of the sputtering gas Ar and the reactive gas N2. As the sputtering gas content increases, the deposited layer becomes more porous and / or fibrous in its microstructure. Further details and other aspects and features of the method can be found in DE application 102021115970.9 and / or WO2022268655A1 filed on June 21, 2021, the entire contents of which are incorporated herein by reference.

[0078] As an example of a combined approach to application, there can be a two-step process of applying the notch absorber layer (and optionally the base layer) by sputtering and then adding a diamond coating top layer to the sputtered notch absorber layer. This can be accomplished by transferring to a diamond coating chamber for adding the diamond top layer to the sputtered base layer and the sputtered notch absorber layer.

[0079] Although specific reference may be made herein to the use of lithographic apparatus in IC manufacturing, it should be understood that the lithographic apparatus described herein may have other applications. Possible other applications include the manufacture of integrated optical systems, guidance and detection patterns for magnetic domain memories, flat panel displays, liquid crystal displays (LCDs), thin film magnetic heads, and the like.

[0080] Although specific reference may be made herein to embodiments of the present invention in the context of lithographic apparatus, embodiments of the present invention may be used in other apparatus. Embodiments of the present invention may form part of a mask inspection apparatus, a metrology apparatus, or any apparatus for measuring or processing an object such as a wafer (or other substrate) or a mask (or other patterning device). These apparatuses are generally referred to as lithographic tools. Such lithographic tools may utilize vacuum conditions or ambient (non-vacuum) conditions.

[0081] Although specific reference has been made above to the use of embodiments of the invention in the context of optical lithography, it will be appreciated that the invention is not limited to optical lithography and may be used in other applications, such as imprint lithography, where the context permits.

[0082] Where the context permits, embodiments of the present invention may be implemented in hardware, firmware, software, or any combination thereof. Embodiments of the present invention may also be implemented as instructions stored on a machine-readable medium, which may be read and executed by one or more processors. A machine-readable medium may include any mechanism for storing or transmitting information in a form readable by a machine (e.g., a computing device). For example, a machine-readable medium may include read-only memory (ROM); random access memory (RAM); magnetic storage media; optical storage media; flash memory devices; electrical, optical, acoustic, or other forms of propagated signals (e.g., carrier waves, infrared signals, digital signals, etc.), etc. In addition, firmware, software, routines, instructions may be described herein as performing certain actions. However, it should be understood that such descriptions are merely for convenience, and that such actions are actually produced by a computing device, processor, controller, or other device that executes the firmware, software, routines, instructions, etc., and in doing so, may cause an actuator or other device to interact with the physical world.

[0083] While specific embodiments of the present invention have been described above, it will be appreciated that the present invention may be practiced otherwise than as described. The foregoing description is intended to be illustrative and not limiting. Therefore, it will be apparent to those skilled in the art that modifications may be made to the described invention without departing from the scope of the following claims.

[0084] Example

[0085] 1. A holding device (100), suitable for holding a structural component, in particular a semiconductor wafer (W) or a photolithography mask, comprising:

[0086] a base body (16) formed by at least one plate (17) having an upper side, and

[0087] a contact surface (19) having a predetermined flatness on the upper side of the plate (17) for contacting the structural component,

[0088] wherein a notch-absorbing layer (21) is provided on the upper side of the plate (17), said notch-absorbing layer having such a low volume density that, under the mechanical action of foreign particles (15), said notch-absorbing layer (21) can be compressed by compaction in the layer volume without impairing the flatness of the contact surface (19),

[0089] wherein a multilayer laminate (20) is provided on the upper side of the plate (17), the multilayer laminate comprising the notch-absorbing layer (21) and a top layer (22) arranged on the notch-absorbing layer (21),

[0090] At least one of the notch absorber layer (21) and the top layer (22) comprises at least one of boron and carbon.

[0091] 2. The holding device (100) according to example 1, wherein the volume density of the notch absorbing layer (21) is less than the volume density of the solid material of the notch absorbing layer (21).

[0092] 3. A retaining device (100) according to Example 2, wherein the volume density of the notch absorption layer (21) is in the range of 90% to 10% of the volume density of the solid material of the notch absorption layer (21), preferably in the range of 85% to 10%, and even more preferably in the range of 85% to 50%.

[0093] 4. The holding device (100) according to any preceding example, wherein the top layer (22) has a greater bulk density than the notch absorbing layer (21).

[0094] 5. A holding device (100) according to Example 4, wherein the volume density of the notched absorption layer (21) is in the range of 90% to 10% of the volume density of the top layer (22), preferably in the range of 85% to 10%, and even more preferably in the range of 85% to 50%.

[0095] 6. The holding device (100) according to any preceding example, wherein the top layer (22) has a greater hardness than the notch absorbing layer (21).

[0096] 7. The holding device (100) according to any preceding example, wherein the top layer (22) and the notch absorbing layer (21) are formed from the same material.

[0097] 8. The holding device (100) according to any preceding example, wherein at least one of the notch absorbing layer (21) and the top layer (22) comprises diamond.

[0098] 9. The holding device (100) of example 8, wherein the notch absorbing layer (21) and the top layer (22) comprise diamond.

[0099] 10. The holding device (100) according to any preceding example, wherein at least one of the notch absorbing layer (21) and the top layer (22) comprises at least one of graphene, boron nitride, carbon nitride and boron carbon nitride.

[0100] 11. The holding device (100) of example 10, wherein at least one of the notch absorbing layer (21) and the top layer (22) comprises B, B4C, BC2, BC3, C, C3N4, N, BN, B 2.5 At least one of N, BCN, BC2N, and BC4N.

[0101] 12. The holding device (100) according to any preceding example, wherein the notch absorbing layer (21) comprises at least one of the following: CrN, metal, ceramic including nitride, and ceramic including carbide.

[0102] 13. The holding device (100) according to any preceding example, wherein the top layer (22) comprises at least one of boron or carbon.

[0103] 14. The holding device (100) according to any preceding example, wherein the notch-absorbing layer (21) is a porous and / or fibrous layer.

[0104] 15. The holding device (100) of example 14, wherein the notch absorbing layer (21) has a nano-sized or ultra-nano-sized porosity.

[0105] 16. The holding device (100) according to any preceding example, wherein the multilayer laminate (20) comprises a substrate layer (23) arranged between the plate (17) and the notch absorbing layer (21).

[0106] 17. The holding device (100) of example 16, wherein the base layer (23) has a greater bulk density than the notch absorbent layer (21).

[0107] 18. The holding device (100) according to any one of examples 16 or 17, wherein the base layer (23) has a greater hardness than the notch absorbing layer (21).

[0108] 19. The holding device (100) according to any one of examples 16-18, wherein the base layer (23) and the notch absorbing layer (21) and / or the top layer (22) are formed from the same material.

[0109] 20. Holding device (100) according to any preceding example, wherein the contact surface (19) is formed by a plurality of protruding studs (18) arranged on the upper side of the plate (17).

[0110] 21. A lithographic device arranged to project a pattern from a lithographic mask onto a semiconductor wafer, wherein the lithographic device comprises an illumination system configured to adjust a radiation beam, wherein the illumination system is configured to project the radiation beam onto the lithographic mask, wherein the lithographic device comprises a holding device as described in any of the preceding examples, and the structural component comprises the lithographic mask or the semiconductor wafer.

[0111] 22. A method for producing a holding device (100) suitable for holding a structural component, in particular a semiconductor wafer (W) or a photolithography mask, comprising the following steps:

[0112] providing a base body (16) formed by at least one plate (17) having an upper side, wherein a contact surface (19) on the upper side of the plate (17) has a predetermined flatness for contacting the structural component,

[0113] forming a notch-absorbing layer (21) on the upper side of the plate (17), wherein the notch-absorbing layer (21) has such a low volume density that, under the mechanical action of foreign particles (15), the notch-absorbing layer (21) can be compressed by compaction in the layer volume without impairing the flatness of the contact surface (19),

[0114] depositing a multilayer laminate (20) on the upper side of the plate, wherein the multilayer laminate (20) comprises the notch absorbing layer (21) and a top layer (22) arranged on the notch absorbing layer (21),

[0115] At least one of the notch absorber layer (21) and the top layer (22) comprises at least one of boron and carbon.

[0116] 23. The method of example 22, wherein the multilayer laminate (20) comprises a substrate layer (23) disposed between the plate (17) and the notch-absorbing layer (21).

[0117] 24. A method according to any one of Examples 22 or 23, wherein at least one of the notch absorption layer (21), the top layer (22) and the base layer (23) is formed by chemical vapor deposition, preferably linear antenna microwave chemical vapor deposition.

[0118] 25. The method of any one of examples 22-24, wherein the top layer (22) and / or the base layer (23) are formed of the same material as the notch absorbing layer (21), and

[0119] During the deposition of the multilayer laminate (20), process parameters of the deposition are varied in such a way that the notch absorber layer (21) is formed to have a lower volume density than the top layer (22) and / or the base layer (23).

Claims

1. An object holder (100) configured to support an object, the object holder comprising: a base body (16) formed by a plate (17) having an upper side, and a contact surface (19) having a predetermined flatness on the upper side of the plate (17) for contacting the object, wherein a notch-absorbing layer (21) is provided on the upper side of the plate (17), said notch-absorbing layer having such a low volume density that, under the mechanical action of foreign particles (15), said notch-absorbing layer (21) can be compressed by compaction in the layer volume without impairing the flatness of the contact surface (19), wherein a multilayer laminate (20) is provided on the upper side of the plate (17), the multilayer laminate comprising the notch absorbent layer (21) and a top layer (22) arranged on the notch absorbent layer (21), At least one of the notch absorber layer (21) and the top layer (22) comprises at least one of boron and carbon.

2. The object holder (100) according to claim 1, wherein the volume density of the notch absorbing layer (21) is less than the volume density of the solid material of the notch absorbing layer (21), Preferably, the volume density of the notch absorption layer (21) is in the range of 90% to 10%, more preferably in the range of 85% to 10%, and even more preferably in the range of 85% to 50%, of the volume density of the solid material of the notch absorption layer (21).

3. The object holder (100) according to any one of the preceding claims, wherein the top layer (22) has a greater bulk density than the notch absorbing layer (21), Preferably, the volume density of the notched absorbent layer (21) is in the range of 90% to 10%, more preferably in the range of 85% to 10%, even more preferably in the range of 85% to 50% of the volume density of the top layer (22).

4. An object holder (100) according to any of the preceding claims, wherein the top layer (22) has a greater hardness than the notch absorbing layer (21), or / and wherein the top layer (22) and the notch absorbing layer (21) are formed of the same material.

5. The object holder (100) according to any one of the preceding claims, wherein at least one of the notch absorbing layer (21) and the top layer (22) comprises diamond, or wherein the notch absorbing layer (21) and the top layer (22) comprise diamond.

6. The object holder (100) according to any one of the preceding claims, wherein at least one of the notch absorbing layer (21) and the top layer (22) comprises at least one of graphene, boron nitride, carbon nitride and boron carbon nitride.

7. The object holder (100) according to claim 6, wherein at least one of the notch absorbing layer (21) and the top layer (22) comprises B, B4C, BC2, BC3, C, C3N4, N, BN, B 2.5 At least one of N, BCN, BC2N, and BC4N.

8. An object holder (100) according to any of the preceding claims, wherein the notch absorbing layer (21) comprises at least one of the following: CrN, metal, ceramic including nitride and ceramic including carbide, or / and wherein the top layer (22) comprises at least one of boron or carbon, or / and wherein the notch absorbing layer (21) is a porous and / or fibrous layer.

9. The object holder (100) according to claim 8, wherein the notch absorbing layer (21) has a nano-sized or ultra-nano-sized porosity.

10. An object holder (100) according to any of the preceding claims, wherein the multilayer laminate (20) includes a base layer (23), which is arranged between the plate (17) and the notch absorbing layer (21), wherein the base layer (23) has a greater volume density than the notch absorbing layer (21).

11. The object holder (100) according to claim 10, wherein the base layer (23) has a greater hardness than the notch absorbing layer (21), or / and The base layer (23) and the notch absorbing layer (21) and / or the top layer (22) are formed of the same material.

12. The object holder (100) according to any one of the preceding claims, wherein the contact surface (19) is formed by a plurality of protruding studs (18) or burls arranged on the upper side of the plate (17).

13. An object holder (100) configured to support an object, the object holder comprising: Matrix (16), a plurality of protrusions on the base, the plurality of protrusions forming a contact surface (19) having a predetermined flatness for contacting the object, wherein each burl of the plurality of burls comprises a multi-layer laminate (20) comprising a notch absorbing layer (21) and a top layer (22) disposed on the notch absorbing layer (21), wherein the notch-absorbing layer (21) has such a low volume density that, under the mechanical action of foreign particles (15), the notch-absorbing layer (21) can be compressed by compaction in the layer volume without impairing the flatness of the contact surface (19), At least one of the notch absorber layer (21) and the top layer (22) comprises at least one of boron and carbon.

14. A lithographic apparatus comprising an object holder according to any one of claims 1 to 13.

15. A method for manufacturing an object holder (100), the object holder (100) being adapted to hold an object, the method comprising the steps of: providing a base body (16) formed by a plate (17) having an upper side, wherein a contact surface (19) on the upper side of the plate (17) has a predetermined flatness for contacting the object, forming a notch-absorbing layer (21) on the upper side of the plate (17), wherein the notch-absorbing layer (21) has such a low volume density that, under the mechanical action of foreign particles (15), the notch-absorbing layer (21) can be compressed by compaction in the layer volume without impairing the flatness of the contact surface (19), depositing a multilayer laminate (20) on the upper side of the plate, wherein the multilayer laminate (20) comprises the notch absorbing layer (21) and a top layer (22) arranged on the notch absorbing layer (21), At least one of the notch absorber layer (21) and the top layer (22) comprises at least one of boron and carbon.

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