Holding device for holding a structural part and method for manufacturing the holding device

Abstract

This invention provides a holding device 100 for holding a structural portion (specifically, a semiconductor wafer 1 or a photomask), the holding device comprising: a substrate 10 formed of at least one plate 11 having an upper side surface; and a plurality of protruding posts 12 disposed on the upper side surface of the plate 11 and forming a contact surface 13 having a predetermined flatness for contacting one of the structural portions, wherein a notched absorption layer 21 is provided on the upper side surface of the plate 11, having such a low volume density that the notched absorption layer 21 can be compressed by compaction of one layer volume under the mechanical action of foreign particles 2 without compromising the flatness of the contact surface 13. A method for manufacturing the holding device 100 for holding one of the structural portions is also described.

Description

Technical Field

[0001] This invention relates to a holding device adapted to hold a disk-shaped structural portion, specifically a semiconductor wafer or photomask, and to a method for manufacturing this holding device. Specifically, this invention relates to a wafer clamp, photomask clamp, wafer chuck, or photomask chuck for holding the semiconductor wafer or photomask during processing, and to a method for manufacturing such a device. The application of this invention occurs in the processing of structural portions (especially semiconductor wafers). Prior Technology

[0002] In this specification, reference is made to the following prior art, which illustrates the technical background of the present invention: [1] US 4 502 094; [2] US 2013 / 0308116 A1; [3] WO 2020135971 A1; [4] US 20150311108 A1; [5] US 20140368804 A1; [6] JP ​​2015167159 A; and [7] DE 202009007494 U1. Summary of the Invention

[0003] Generally, holding devices are known for holding disk-shaped or plate-shaped structural portions in lithography (wafer manufacturing), such as for holding semiconductor wafers, specifically silicon wafers. Depending on the applied holding force, there is a distinction between electrostatic holding devices used for electrostatically holding structural portions and vacuum holding devices used for holding structural portions under negative pressure.

[0004] Typically, for example, an electrostatic holding device has a substrate with several plate or layered elements (see, for example, [1], [2]), wherein at least one plate element is equipped with an electrode device for generating electrostatic holding force. At least one plate element is made of mechanically rigid ceramic to satisfy load-bearing and cooling functions. Furthermore, the electrostatic holding device typically has, for example, at least one exposed surface on its upper side, formed by a plurality of protruding posts. The end faces of the posts form contact surfaces for the structural portion to be held.

[0005] For use in chip manufacturing, for example, the contact surface spanned by the pillars should be as flat as possible. This is because unevenness can cause bending of the held semiconductor wafer and thus lead to errors in its construction during chip manufacturing. Unevenness of a few nanometers in positioning, such as a pillar protruding >10 nm, can already cause unacceptable bending of the semiconductor wafer.

[0006] The flatness of the contact surface spanned by the end face of the post can be damaged by notches on the surface of the holding device. For example, notches can be caused by mechanical influences (such as by foreign particles (notch damage)). Notches can be caused, for example, by sharp or pointed particles that adhere to the back side of the semiconductor wafer when it is pressed against the contact surface during processing.

[0007] The notch that acts as a gap in the end face does not actually directly impair the flatness of the contact surface. However, local build-up or protrusion near the notch is attributed to material displacement caused by penetrating foreign particles (which impair flatness).

[0008] Notch damage limits the lifespan of retaining devices. Rebuilding retaining devices is costly due to downtime and the need for their handling. Therefore, minimizing notch damage is a concern.

[0009] Well-known processes for preventing notch damage typically involve providing the end face of the pillar with the hardest possible protective layer. However, even with a hard protective layer on the end face, notch damage cannot be reliably eliminated. Furthermore, defects can also be attributed to mechanical stress on the semiconductor wafer. Specifically, when the lower side of the semiconductor wafer resting on the contact surface is formed of a hard material (such as SixNy or Al2O3), stress can lead to damage to the semiconductor wafer or pillar.

[0010] Other layer configurations for modifying the column (specifically for adjusting hardness and friction properties) are also known, thereby providing a single layer or multiple layers (see [3], [4], [5] and [6]). However, these layers are not effective in preventing the aforementioned notch damage.

[0011] Self-encapsulation technology (e.g., see [7]) is familiar with the concept of an embedded shock-absorbing layer. In the event of surface damage caused by a foreign object on the encapsulation with an shock-absorbing layer, the penetrating foreign object is absorbed by the shock-absorbing layer and the encapsulated article is protected. However, since conventional shock-absorbing layers are made of plastic or cardboard with a typical thickness in the cm range, they protrude from the surface of the encapsulation near the foreign object.

[0012] The objective of this invention is to provide an improved holding device for holding structural parts and an improved method for manufacturing the holding device for holding structural parts, which avoids the disadvantages of the prior art. Specifically, the objective of this invention is to improve the holding device in a way that reduces its sensitivity to notch damage, extends its service life, reduces manufacturing and use costs, and / or tends to reduce mechanical stress caused by impurities (such as particles).

[0013] This objective is achieved by a holding device for holding structural portions and a method for manufacturing the holding device, both of which have features covered by the independent patent claims. Preferred embodiments and applications of the invention will become apparent from the appended patent claims.

[0014] According to a first general embodiment of the present invention, the aforementioned objective is achieved by a holding device adapted to hold a structural portion, specifically a disk-shaped structural portion, such as a semiconductor wafer or a photomask, and comprising: a substrate formed of at least one plate having an upper side surface; and a plurality of protruding pillars disposed on the upper side surface of the plate and forming contact surfaces with a predetermined flatness for contacting the structural portion. According to the present invention, a notched absorption layer is provided on the upper side surface of the plate, having such a low volume density that the notched absorption layer can be compressed by compaction within its volume under the mechanical action of foreign particles without compromising the flatness of the contact surface (specifically, on the contact surface, i.e., facing the upper side surface of the holding device).

[0015] According to a second general embodiment of the invention, the aforementioned objective is achieved by a method for manufacturing a holding device adapted to hold a structural portion, specifically a disk-shaped structural portion, such as a semiconductor wafer or a photomask. For example, the holding device provides a substrate formed of at least one plate having an upper side surface, wherein a plurality of protruding pillars are disposed on the upper side surface of the plate, the protruding pillars forming a contact surface with a predetermined flatness for contacting the structural portion. According to the invention, a notched absorption layer is formed on the upper side surface of the plate, whereby the notched absorption layer has such a low volume density that it can be compressed by compaction within the layer volume under the mechanical action of foreign particles without compromising the flatness of the contact surface. Preferably, the holding device according to the first general embodiment of the invention or any embodiment thereof is manufactured using a method for manufacturing a holding device according to an embodiment of the second general embodiment or method of the invention.

[0016] The holding device can be, for example, an electrostatic holding device (also known as an electrostatic wafer panel, electrostatic clamping device, electrostatic clamp, ESC, or electrostatic chuck) or a vacuum holding device (also known as a vacuum clamp or vacuum chuck). The spatial direction parallel to the contact surface of the holding device is called the lateral direction, and the direction perpendicular to it is called the thickness direction (z-direction). In the lateral direction, the substrate preferably has a flat area parallel to the contact surface, and it can be formed by one or more plates stacked and joined together in the thickness direction. The upper side of the substrate is provided for contacting and holding the structural portion. When the holding device is adjusted to contact and hold the structural portion on both sides, each side forms an upper side, in which case a notched absorption layer is preferably provided on both sides.

[0017] The notched absorbent layer is a preferred flat layer in the structure of the substrate, extending parallel to the contact surface (preferably over the entire area of ​​the contact surface). The notched absorbent layer may be a continuous layer or may comprise multiple layer segments limited to the lateral extension of the column (specifically, to the end face of the column).

[0018] The term "foreign particle" refers to any impurity (foreign substance or defect) that may appear between the contact surface and the structural portion to be secured during use of the securing device. Impurities may specifically include, for example, particles, fibers, and / or compositions of particles and / or fibers having a round or angular, compact or elongated form. Impurities may be formed, for example, by means of the material of the structural portion to be secured, the material of the securing device, and / or materials from the environment. The notched absorbent layer is adapted to at least partially contain (absorb) the volume of foreign particles, specifically protruding defects on the back side of the structural portion.

[0019] The structure of the notched absorber layer preferably contains cavities and spaces between the atomic components of the material, resulting in a reduced bulk density and, depending on the case, a reduced hardness compared to materials without microscopic gaps. Consequently, foreign particles pressed against the contact surface of the substrate by a force component in the thickness direction can be locally displaced and compress the atomic components of the notched absorber layer material. The material within the layer volume of the notched absorber layer is compressed, and localized compression occurs near the foreign particles.

[0020] The inventors have discovered that compaction primarily occurs in the lateral direction and / or thickness direction to the depth of the notched absorber layer, while localized accumulation near foreign particles on the thickness of the notched absorber layer is eliminated or minimized to a negligible level. Advantageously, the compression of the notched absorber layer does not impair the flatness of the contact surface. Therefore, the notched absorber layer is advantageously distinguished from conventional impact absorber layers with surface protrusions formed therein.

[0021] Other advantages of this invention are that the notch absorber layer reduces sensitivity to notch damage due to the absorption of foreign particle volume. Since flatness is not compromised by foreign particles, especially during the use of the holding device, the notch absorber layer provides an extended service life for the holding device. Furthermore, this invention offers the advantages that the notch absorber layer is easy to manufacture, and therefore the cost of the holding device remains almost unchanged compared to conventional holding devices, while the cost of using the holding device is significantly reduced due to shortened downtime. Finally, the mechanical stress generated by particles is prevented or reduced to a negligible level.

[0022] The term "flatness" refers to the allowable shape tolerance of the flat contact surface of a positioning and holding device, whereby the tolerance limit is formed by two surfaces parallel to the ideally generated contact surface. Flatness is compromised if the resulting actual contact surface protrudes through one of the parallel surfaces, specifically through the surface above the holding device. The tolerance limits are specified based on the specific use of the holding device (specifically, the required accuracy of the process, the flexibility of the held structure, and the flexibility of the post). The tolerance limits are specifically determined in the positioning area by the flatness along the upper side of the held structure. For example, for a silicon wafer with a thickness of 0.775 mm, these tolerance limits are equal to or less than + / - 16 nm; specifically, for a positioning area with a diameter of 3 mm, these tolerance limits are equal to or less than + / - 3 nm.

[0023] Although the localized damage to the flatness in the direction of the depth of the material (i.e., towards the substrate) is not critical for the contact function of the contact surface and can be tolerated, the localized damage to the flatness beyond the level of the contact surface (i.e., away from the substrate) will be a problem because such localized damage can interfere with the flatness of the held structural part. With the notch absorption layer according to the present invention, the flatness is maintained within a specified tolerance, specifically above the contact surface, by avoiding upward protrusions (convexities, deposits or bulges).

[0024] According to a preferred embodiment of the present invention, the notch absorption layer is a porous and / or fibrous layer with columnar growths. The provision of a porous and / or fibrous notch absorption layer has the advantage that the adjustment of the volume density (specifically, the pores between the grains or the fiber density or volume) is simplified during the manufacture of the notch absorption layer (e.g., during layer deposition from the gas phase). Preferably, the pore and / or fiber density is adjusted in such a way that the volume density of the notch absorption layer is selected, for example, within the range of 90% to 10% of the volume density of the solid material of the notch absorption layer, specifically within the range of 85% to 10%, such as within the range of 85% to 50%. Here, the term "solid material" refers to a single crystal having the same chemical composition and crystal structure as the notch absorption layer, or, if the material of the notch absorption layer does not form a single crystal and / or does not present reliable data, to a theoretically defect-free material having the same composition and atomic structure as the notch absorption layer.

[0025] Further advantages of the present invention emerge from the plurality of configuration variants of the notch absorption layer, such that it can be optimally adjusted to the structure and materials of the other components of the holding device. According to a preferred variant, the notch absorption layer can be formed from ceramics and / or metals. For example, the notch absorption layer can consist of ceramics or metals, or can comprise a multi-layer configuration having several ceramics or several metals, or a multi-layer configuration having at least one ceramic and at least one metal. For example, the notch absorption layer can be formed from Cr xN, where 0.9 < x < 2.2, or from the compound Cr xM yN, where 0 < x < 2.2, specifically, 0.3 < x < 2.2 and 0 < y < 1, where M comprises an additional metal, specifically Al, Si or Ti. CrN and Cr xM yN have specific advantages regarding the adjustment of the volume density of the notch absorption layer. Alternatively or additionally, the notch absorption layer can have a thickness within the range of 300 nm to 20 µm, specifically within the range of 500 nm to 5 µm.

[0026] The notch absorber layer can be formed to serve as the uppermost exposed layer on the upper side of the holding device. Alternatively, according to another advantageous embodiment of the invention, a multilayer composite is provided on the upper side of the plate, comprising: a notch absorber layer; and a further top layer disposed on the notch absorber layer; an adhesive layer (also referred to as a base layer) disposed between the plate and the notch absorber layer; and / or a crack mitigation layer adapted to deflect crack propagation. Preferably, the deposition of the multilayer composite occurs during the manufacture of the holding device.

[0027] The top layer and / or adhesive layer may be made of, for example, the same material as the notch absorber layer or a different material. The top layer and / or adhesive layer may have a thickness, for example, in the range of 10 nm to 20 µm. The crack mitigation layer may comprise: several sublayers configured for crack mitigation at the interfaces between the sublayers; and / or a material capable of plastic deformation with increased fracture strength, such as a metal. The thickness of the crack mitigation layer may be selected, for example, in the range of 200 nm to 5 µm, or several crack mitigation layers may be provided having a cumulative thickness of 200 nm to 5 µm.

[0028] Advantageously, the notched absorbent layer in the multilayer structure is a single layer, preferably having an intermediate layer (or, in the case of a two-layer structure, a lower layer) that reduces density (specifically, increases porosity). In the multilayer composite, the notched absorbent layer is compressible / compactable, allowing it to absorb additional volume from the imprinting of foreign particles. This function according to the invention is advantageously combined with the function of at least one additional layer in the multilayer composite without being compromised by the function of at least one additional layer.

[0029] When a multilayer composite includes a top layer, the top layer preferably has greater hardness and less thickness than the notch absorber layer. The inventors have discovered that when a harder and thinner top layer is disposed on the notch absorber layer, the notch absorber layer can also absorb foreign particles without compromising flatness.

[0030] Preferably, the top layer and the notch absorber layer are formed from the same material, thereby giving the top layer a greater bulk density than the notch absorber layer. In this variant, there is an advantage in simplifying the fabrication of the top layer and the notch absorber layer using a single deposition method while changing the deposition conditions.

[0031] When a multilayer composite includes an adhesive layer, it is preferable that the adhesive layer and the notch absorber layer are formed from the same material, thereby giving the adhesive layer a greater bulk density than the notch absorber layer. In this variant, there is also the advantage of simplified manufacturing of the adhesive layer and the notch absorber layer.

[0032] According to the method, the deposition of the multilayer composite may preferably include the formation of a top layer and / or an adhesive layer, wherein the top layer and / or adhesive layer are formed of the same material as the notch absorber layer, and during the deposition of the multilayer composite, the deposition process parameters are changed in a way that the notch absorber layer forms a lower bulk density than the top layer and / or adhesive layer.

[0033] According to another advantageous embodiment of the invention, a notched absorbent layer is disposed on the end face of the column. The notched absorbent layer is located near or on the free end of at least one plate of the column opposite to the holding device, the free end of which spans the contact surface of the holding device. In this variant of the invention, the notched absorbent layer is preferably deposited on the column, for example, the column may be made of the same material as the plate. First, it is preferred to provide a substrate having a plate and a column on the upper side of the plate, and the notched absorbent layer is formed on the end face of the column. The notched absorbent layer or a top layer provided on the notched absorbent layer forms the contact surface of the structural portion to be held. This embodiment has the advantage that a holding device known per se can be simply equipped with a notched absorbent layer. Furthermore, the rebuilding of the holding device (which may be necessary after an operating cycle) is particularly facilitated by the renewal of the notched absorbent layer.

[0034] According to an alternative advantageous embodiment of the invention, a multilayer composite as mentioned above is provided, wherein the notched absorbent layer is part of the multilayer composite, and the multilayer composite is structured in such a way that the column is formed by the multilayer composite. Advantageously, in this case, the column is specifically formed by the multilayer composite. According to the method, preferably, a substrate having a plate but no column on the upper side is first provided, then a multilayer composite is deposited on the upper side of the plate, and then the multilayer composite is structured in such a way that the column on the upper side of the plate is formed by the multilayer composite.

[0035] Another advantage of this invention is that the notched absorber layer can be easily manufactured and different deposition methods can be used to manufacture it. Preferably, the notched absorber layer is formed by reactive magnetron sputtering. Reactive magnetron sputtering has the particular advantage that the bulk density of the notched absorber layer (and suitable other layers in the multilayer composite) can be easily adjusted by modifying the sputtering conditions. Simple Explanation of the Diagram

[0036] Further details and advantages of the invention will be described below with reference to the accompanying drawings. In the drawings:

[0037] Figure 1: Showing features of a preferred embodiment of the holding device according to the present invention;

[0038] Figure 2: Showing a variant of the invention, wherein a notched absorbent layer is formed on the column of the retaining device;

[0039] Figure 3: Showing a variant of the invention, wherein the post of the retaining device is formed by a notched absorbent layer; and

[0040] Figure 4 shows the experimental test results obtained using the notched absorption layer according to the present invention. Implementation

[0041] Features of embodiments of the present invention will be described below by way of example with reference to the formation, configuration, and function of the notch absorber layer. Features of the holding device for semiconductor wafers (equipped with the notch absorber layer), such as details of the substrate (e.g., cooling or electrode devices), will not be described, as these are known from conventional holding devices. The present invention is not limited to holding devices for semiconductor wafers, but can also be applied, for example, in corresponding manner to holding devices for other structural components (such as those for glass plates or photomasks).

[0042] This invention is not limited to the materials, sizes, and forms specified by way of example. In particular, the notched absorber layer may be formed of a material different from the CrN specified by way of example.

[0043] The lower portion of Figure 1 schematically shows a holding device 100 for holding a semiconductor wafer 1, which has a base 10 having a plate 11 and a plurality of posts 12 in a manner known per se. The end faces of the posts 12, protruding in the z-direction, span the contact surface 13 of the holding device 100 for receiving the semiconductor wafer 1. The side of the plate 11 on which the semiconductor wafer 1 is placed is the upper side of the plate 11. The plate 11 is made of, for example, a SiSiC glass composite, and the posts 12 are made of, for example, glass or ceramic. It is emphasized that Figure 1 is an illustrative description. In a practical example, the posts have, for example, a height of 10 µm, a width of 220 µm, and a spacing of 1.5 mm. One of the posts 12 is schematically enlarged in the middle portion of Figure 1.

[0044] In each case, the notched absorbent layer 21 is disposed on the upper end of the column 12. In the depicted example, the notched absorbent layer 21 is the uppermost layer, such that the end face and the contact surface 13 are spanned by the entire layer section of the notched absorbent layer 21 on the column 12.

[0045] In the upper part of Figure 1, the notch absorber layer 21 and its operation are further magnified and explained. For example, the notch absorber layer 21 is composed of porous CrN with a thickness of 3 µm. When the semiconductor wafer 1 is placed in the appropriate position, if an intrusive particle 2 (not shown) appears on the contact surface of the semiconductor wafer 1 or on the surface of the notch absorber layer 21, the intrusive particle 2 is pressed into the notch absorber layer 21. This results in a notch 21A, which is not critical to the function of the holding device 100, specifically to the flat contact of the semiconductor wafer 1. Near the notch 21A, the material of the notch absorber layer 21 is compressed by the intrusive particle 2 to prevent upward protrusion and to avoid damaging the upward flatness of the contact surface 13. The intrusive particle 2 can remain adhered to the notch absorber layer 21, can remain adhered to the back side of the wafer, or can be removed by cleaning the surface.

[0046] Unlike the single-layer notched absorbent layer 21 according to FIG. 1, a multilayer laminate 20 can be provided, as illustrated in FIG. 2 and FIG. 3. In the multilayer laminate 20, the notched absorbent layer 21 is embedded between the top layer 22 and the adhesive layer 23. According to FIG. 2, the multilayer laminate 20 is deposited on the upper side of the column 12, and according to FIG. 3, the column 12 is formed by the multilayer laminate 20.

[0047] Contrary to the description, the multilayer composite 20 may comprise only two or more layers. The layers may be formed of the same or different materials. Specifically, in the embodiment according to FIG3, it may be advantageous to form a multilayer composite 20 with additional and / or thicker layers to achieve the desired column height.

[0048] In a first example, the layers in the multilayer compound 20 comprise an adhesive layer 23 made of CrN with a thickness of 5.5 µm, a notched absorber layer made of porous CrN with a thickness of 3 µm, and a top layer 22 made of CrN with a thickness of 1.5 µm. In a second example, the adhesive layer 23 is made of CrN with a thickness of 0.1 µm, the notched absorber layer is made of porous CrN with a thickness of 3 µm, and the top layer 22 is made of CrN with a thickness of 1.4 µm. The top layer 22 has the hardness and frictional properties of the CrN top layer, as is known from conventional retaining devices. The hardness of the adhesive layer 23 can be selected to be equal to or greater than the hardness of the top layer 22. The notched absorber layer 21 has the lowest hardness due to its porosity.

[0049] For example, layers 21, 22, and 23 are fabricated using reactive magnetron sputtering. The hardness difference between the layers is adjusted by partially controlling the pressure (or gas flow) of the sputtering gas Ar and the reactive gas N2. Increasing the sputtering gas content results in a more porous deposited layer and / or fibrous microstructure.

[0050] The inventors have investigated the properties of the multilayer compound 20 of the first example and the properties of a conventional single CrN top layer with thicknesses of 1.2 µm and 10 µm under impact from a test tool with a hard tip, as measured by AFM. When the tip is pressed in with thrusts of 100 mN and 200 mN, the conventional CrN top layer results in convexities and cracks greater than 170 nm up to 300 nm in the z-direction, as well as indentations ranging from about 1 µm to 2.1 µm. Under the same test conditions, the multilayer compound 20 advantageously exhibits convexities less than 50 nm and no cracks, and also indentations ranging from about 1.6 µm to 2.2 µm. These results demonstrate that flatness is substantially less impaired by the absorption effect of the notched absorption layer 21, and that particles can be effectively absorbed by the notched absorption layer 21.

[0051] By way of example, Figure 4 uses a TEM cross-sectional image of the multilayer composite 20 according to the first example to illustrate the imprinting effect of the test tool. The tip of the test tool penetrates the top layer 22 and displaces and compresses the material of the notch absorber layer 21, while the adhesive layer 23 remains unchanged.

[0052] The features of the invention disclosed in the foregoing description, drawings and claims, whether individually or in combination or sub-combination, are important for implementing the invention in various configurations.

[0053] 1: Semiconductor wafer 2: Extraterrestrial particles 10: Matrix 11: Board 12: Column 13: Contact Surface 21: Notched Absorption Layer 21A: Gap 20: Multilayer composites 22: Top layer 23: Adhesive layer 100: Holding device

Claims

1. A holding device (100) adapted to hold a structural portion, specifically a semiconductor wafer (1) or a photomask, the holding device comprising: a substrate (10) formed of at least one plate (11) having an upper side surface, and a plurality of protruding studs (12) disposed on the upper side surface of the plate (11) and forming a contact surface (13) having a predetermined flatness for contacting the structural portion, characterized in that: a notch absorption layer (21) is provided on the upper side surface of the plate (11) having such a low volume density that the notch absorption layer (21) can be compressed by compaction of one layer volume in the event of mechanical action of foreign particles (2) without compromising the flatness of the contact surface (13).

2. The holding device of claim 1, wherein the notched absorbent layer (21) is a porous and / or fibrous layer, and / or the bulk density of the notched absorbent layer (21) is selected to be in the range of 90% to 10% of the bulk density of a solid material of the notched absorbent layer (21).

3. The holding device of claim 1 or 2, wherein at least one of the following features is provided: the notch absorber layer (21) is formed of a ceramic and / or a metal, the notch absorber layer (21) is formed of CrxN, wherein 0.9 < x < 2.2, or is formed of the compound CrxMyN, wherein 0 < x < 2.2 and 0 < y < 1, wherein M comprises another metal, specifically Al, Si or Ti, and the notch absorber layer (21) has a thickness in the range of 300 nm to 20 µm.

4. The holding device as claimed in claim 1 or 2, wherein a multilayer laminate (20) is provided on the upper side of the plate (11), comprising the notch absorber layer (21) and at least one of the following: a top layer (22) disposed on the notch absorber layer (21); an adhesive layer (23) disposed between the plate (11) and the notch absorber layer (21); and a crack mitigation layer adapted to deflect crack propagation.

5. The retaining device of claim 4, wherein the multilayer composite (20) includes the top layer (22), wherein the top layer (22) has a greater hardness and a smaller thickness than the notched absorbent layer (21).

6. The holding device of claim 5, wherein the top layer (22) and the notch absorber layer (21) are formed of the same material, wherein the top layer (22) has a greater bulk density than the notch absorber layer (21).

7. The holding device of claim 4, wherein the multilayer composite (20) includes the adhesive layer (23), wherein the adhesive layer (23) and the notch absorber layer (21) are formed of the same material, and the adhesive layer (23) has a greater bulk density than the notch absorber layer (21).

8. The holding device of any one of claims 1 to 2, wherein the notched absorbent layer (21) is disposed on the end face of the columns (12).

9. The holding device as claimed in claim 4, wherein the multilayer composite (20) is structured in such a way that the columns (12) are formed by the multilayer composite (20).

10. The holding device of claim 1, wherein one structure of the notched absorber layer contains cavities and spaces between atomic components of the material of the notched absorber layer.

11. The retaining device of claim 2, wherein the notched absorbent layer is the porous and / or fibrous layer having columnar growth.

12. The retaining device of claim 2, wherein the bulk density of the notch absorber layer is selected to be in the range of 85% to 50% of the bulk density of the solid material in the notch absorber layer.

13. The holding device of claim 2, wherein the bulk density of the notch absorber layer is selected to be in the range of 85% to 10% of the bulk density of the solid material in the notch absorber layer.

14. The retaining device of claim 4, wherein the multilayer composite comprises the notched absorbent layer, the top layer and the adhesive layer, wherein the top layer is disposed on the notched absorbent layer and the notched absorbent layer is embedded between the top layer and the adhesive layer.

15. The retaining device of claim 4, wherein the multilayer composite comprises the notched absorbent layer and the adhesive layer, wherein the notched absorbent layer is an uppermost layer such that the end faces of the plurality of protruding posts and the contact surface are spanned by all layer sections of the notched absorbent layer on the plurality of posts.

16. A method for manufacturing a holding device (100) adapted to hold a structural portion, specifically a semiconductor wafer (1) or a photomask, the method comprising the steps of: providing a substrate (10) formed of at least one plate (11) having an upper side surface, wherein a plurality of protruding pillars (12) are disposed on the upper side surface of the plate (11) forming a contact surface (13) having a predetermined flatness for contacting the structural portion, characterized in that: a notched absorption layer (21) is formed on the upper side surface of the plate (11), wherein the notched absorption layer (21) has such a low volume density that the notched absorption layer (21) can be compressed by compaction of one layer volume in the event of mechanical action of foreign particles (2) without compromising the flatness of the contact surface (13).

17. The method of claim 16, wherein the notched absorber layer (21) is formed by reactive magnetron sputtering.

18. The method of claim 16 or 17, comprising the steps of: depositing a multilayer composite (20) on the upper side of the plate, wherein the multilayer composite (20) comprises the notch absorber layer (21) and at least one of the following: a top layer (22) disposed on the notch absorber layer (21); an adhesive layer (23) disposed between the plate (11) and the notch absorber layer (21); and a crack mitigation layer adapted to deflect crack propagation.

19. The method of claim 18, wherein the deposition of the multilayer composite (20) includes the formation of the top layer (22) and / or the adhesive layer (23), the top layer (22) and / or the adhesive layer (23) being formed of the same material as the notch absorber layer (21), and during the deposition of the multilayer composite (20), the deposition process parameters are modified in such a way that the notch absorber layer (21) forms a lower volume density than the top layer (22) and / or the adhesive layer (23).

20. The method of claim 16 or 17, wherein the substrate (10) is provided with the plate (11) and the columns (12) on the upper side of the plate (11), and the notched absorbent layer (21) is disposed on the end face of the columns (12).

21. The method of claim 18, wherein the substrate (10) is provided with the plate (11) but without the columns (12) on the upper side of the plate (11), the multilayer compound (20) is deposited on the upper side of the plate (11), and the multilayer compound (20) is structured in such a way that the columns (12) are formed on the upper side of the plate (11) by means of the multilayer compound (20).

22. The method of claim 18, wherein the notched absorber layer, the top layer and the adhesive layer are manufactured by reactive magnetron sputtering, and the hardness difference between the notched absorber layer, the top layer and the adhesive layer is adjusted by a portion of the pressure or gas flow of the sputtering gas Ar and the reactive gas N2.

23. The method of claim 18, wherein the multilayer composite comprises the notched absorbent layer, the top layer and the adhesive layer, wherein the top layer is disposed on the notched absorbent layer and the notched absorbent layer is embedded between the top layer and the adhesive layer.

24. The method of claim 18, wherein the multilayer composite comprises the notched absorbent layer and the adhesive layer, wherein the notched absorbent layer is an uppermost layer such that the end faces of the plurality of protruding posts and the contact surface are traversed by the entire layer section of the notched absorbent layer on the plurality of posts.

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