Object holder
By employing heat-treatable metal-Si, metal-Ge multilayer films and chromium nitride layers, the method addresses substrate and optical element flatness issues in lithography apparatuses, ensuring precision and extending component lifespan by in-situ adjustments.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- ASML NETHERLANDS BV
- Filing Date
- 2024-06-21
- Publication Date
- 2026-07-21
AI Technical Summary
Existing lithography apparatuses face challenges in maintaining substrate flatness and optical element deformation due to wear and contamination, leading to performance issues and premature component replacement, especially in extreme ultraviolet (EUV) lithography where vacuum clamping is not feasible, and traditional methods like ion beam figuring and laser ablation introduce contaminants or have limited precision.
The use of metal-Si, metal-Ge multilayer films and chromium nitride layers on support elements, which can be selectively adjusted in height through heat treatment, allowing in-situ correction of surface flatness and shape within the lithography apparatus without material removal or contamination.
This method stabilizes substrate and optical element flatness, extends component lifespan, and corrects overlay and focus errors by compensating for wear and deformation, enhancing precision and reducing downtime.
Smart Images
Figure 2026524194000001_ABST
Abstract
Description
Technical Field
[0001] [Cross - reference to related applications] This application claims the priority of European Patent Application No. 23183500.0 filed on July 5, 2023, the entire content of which is incorporated herein by reference.
[0002] [Technical Field] The present disclosure relates to an object holder, an object table, an optical element, and a lithography apparatus or tool comprising such an object holder, optical element, or object table. The present disclosure also relates to a method for controlling the flatness of a surface. Also described is the use of such an object holder, object table, lithography apparatus or method in a lithography method or lithography apparatus. The object holder may be part of the object table of a lithography apparatus or lithography tool. The present disclosure is particularly applicable to EUV and DUV lithography apparatuses and methods, but is not limited thereto.
Background Art
[0003] A lithography apparatus is a machine constructed to impart a desired pattern onto a substrate. Lithography apparatuses are used, for example, in the manufacture of integrated circuits (ICs). For example, a lithography apparatus projects a pattern on a patterning device (e.g., a mask) onto a layer of radiation - sensitive material (resist) provided on a substrate.
[0004] To project a pattern onto a substrate, a lithography apparatus can use electromagnetic radiation. The wavelength of this radiation determines the minimum size of the features that can be formed on the substrate. A lithography apparatus using extreme ultraviolet (EUV) radiation having a wavelength in the range of 4 - 20 nm, for example 6.7 nm or 13.5 nm, can form smaller features on a substrate than, for example, a lithography apparatus using radiation having a wavelength of 193 nm.
[0005] The substrate to be exposed is supported by a substrate holder (i.e., an object that directly supports the substrate), and the substrate holder may be supported by a substrate table. The substrate holder may have an array of protrusions or support elements called burrs projecting from at least one side. When the substrate is placed on the tops of the burrs on at least one side of the substrate holder, the substrate may be separated from the body of the substrate holder. This can help prevent particles that may be present on the substrate holder (i.e., contaminants such as dust particles) from distorting the substrate holder or the substrate. The total surface area of the burrs may be only a small fraction of the total surface area of the substrate or substrate holder. Therefore, even if particles are trapped between the burrs, their presence is unlikely to have any effect. The tops of the burrs define the plane on which the object rests when it makes contact.
[0006] Due to the high acceleration that substrates may experience when using high-throughput lithography equipment, simply placing the substrate on the bar of the substrate holder may be insufficient. The substrate is clamped in place. Two methods may be used to clamp the substrate in place: vacuum clamping and electrostatic clamping. In vacuum clamping, the space between the substrate holder and the substrate, and optionally the space between the substrate table and the substrate holder, is partially vacuumed, resulting in the substrate being held in place by the relatively high pressure of the gas or liquid above. However, vacuum clamping cannot be used when the environment around the beam path and / or the substrate or substrate holder is kept at low or very low pressure, such as in extreme ultraviolet (EUV) lithography. In this case, it may not be possible to generate a sufficiently large pressure difference across the substrate (or substrate holder) for clamping. Therefore, electrostatic clamping may be used. In electrostatic clamping, a potential difference is generated between the substrate and the substrate table and / or substrate holder. This potential difference can generate a clamping force.
[0007] For example, controlling the flatness of a substrate, such as a wafer, is crucial. Even if a substrate has within specified flatness when not in a lithography apparatus, its flatness may change when held within the apparatus due to forces from electrostatic clamps, vacuum clamps, etc. Therefore, it is necessary to control the so-called functional flatness of the substrate, that is, its flatness at the point of use. Even if an unfixed substrate is within specified flatness, its flatness in that position may not be. Similarly, to obtain optimal results and accuracy, it is desirable to optimize the surface shape of optical elements such as mirrors.
[0008] During use, surfaces wear down and become contaminated, potentially affecting surface flatness. Uneven surface wear limits performance and reduces component lifespan. Replacing worn parts can result in significant downtime for the associated equipment and reduce throughput.
[0009] This disclosure is intended to address at least some of the problems identified above. [Overview of the initiative]
[0010] According to a first aspect of the present invention, an object holder is provided which is configured to support an object, the object holder comprising a support surface having a plurality of support elements, the plurality of support elements comprising a metal-Si multilayer film and / or a metal-Ge multilayer film and / or a chromium nitride layer, and which is configured such that the individual heights of the plurality of support elements can be selectively changed by heat treatment of the metal-Si multilayer film, the metal-Ge multilayer film and / or the chromium nitride layer. The metal may be selected from titanium, molybdenum, or any combination thereof.
[0011] The flatness of object holders such as wafer tables and wafer clamps is adjusted in one of two ways. First, ion beam figuring (IBF) adjusts flatness by etching the surface of the object holder with ion bombardment in an offline setup. Offline setup means that it is performed outside the lithography equipment used to draw the wafer. Individual bar heights can be corrected, and the performance of this correction depends on the spot size of the ion beam. IBF cannot be performed inside a lithography scanner because an ion source is required, and removing the material would cause contaminants to diffuse into the scanner, leading to contamination problems. During operation, flatness can fluctuate (drift) due to various reasons, including wear, dents, and contamination. Flatness greatly contributes to on-product overlay (OPO), and deterioration of flatness necessitates clamp replacement, resulting in long downtime. Similarly, in optical elements such as mirrors and mirror blocks, flatness correction is performed using IBF, but once a mirror coating is applied, the surface flatness can no longer be corrected. While laser ablation can be used to remove material from a target, its suitability is limited by the minimum height removal per pulse, which is approximately 40-60 nm, and the smaller the height difference of the support elements that can cause focusing problems and die defects. Thus, laser ablation can over-remove material and generate unwanted contaminants.
[0012] This disclosure addresses the shortcomings of existing technologies by providing a material that allows for the individual height of support elements to be changed by heating. While it is understood that materials contract and expand with temperature changes, this does not allow for stable changes in the height of support elements such as burrs. On the other hand, by using a material that undergoes a phase transition, such height changes can be stabilized. Stability means that there is no phase change at the operating temperature experienced during nominal use and over the time scale in which the object holder is in nominal use. Thus, this disclosure enables individual adjustment of support elements such as burrs. Since the height of the burr is adjusted without removing material, the adjustment can be achieved within the scanner. This is further advantageous because the functional flatness of the substrate may differ between scanners and this cannot be corrected outside the scanner. This disclosure allows for the support surface to be flat or non-flat to provide functional flatness that corrects differences between individual scanners and ultimately corrects overlay errors and / or focus errors in other parts of the system, for example, by correcting a non-ideal focus plane to focus on a specific wafer. When a Ti-Si multilayer film is heated, TiSi and / or TiSi2 are formed, resulting in dimensional changes. Similar effects are observed in metallic germanium multilayer films. Similarly, it has been found that selective heating can densify chromium nitride layers, leading to a volume reduction. Such volume reductions can be used to adjust the height of support elements. The chemical formula for a Ti-Si multilayer film is TiSi x (0.3 ≤ x ≤ 2) may also apply. A Ti-Si multilayer film may have any number of alternating Ti and Si layers. Similarly, a Mo-Si multilayer film may have any number of alternating Mo and Si layers. Similarly, a metal-Ge multilayer film may use any number of alternating Ge and metal layers. The chemical formula for a metal-Ge multilayer film is MGe x(0.3 ≤ x ≤ 2) may also apply. The multilayer film may contain different metals, different metals may be present in the same layer, and / or in different layers. The thickness of each layer in the multilayer film may be about 2 nm to about 100 nm, preferably about 10 nm to about 20 nm. These layers may be formed by sputtering, optionally by magnetron sputtering. Not all support elements necessarily need to have a multilayer film. It is preferable to provide a multilayer film on the support elements that are most likely to wear during operation.
[0013] For example, a crowbar, whose height can increase by more than 12 nm due to dents or contamination, is sufficient to cause focus problems and die defects. At the edges of the support surface, the support elements are prone to wear, potentially wearing down by approximately 20-50 nm during use, which limits performance. All of these effects limit the lifespan of the support surface, potentially leading to premature replacement and associated downtime. By compensating for the height of the support elements, the desired shape of the support surface can be adjusted, extending the lifespan of the support surface.
[0014] Multiple support elements may be burrs. It will be understood that not all support elements or burrs need to contain a metal-Si multilayer film, a metal-Ge multilayer film, and / or a chromium nitride layer. In some embodiments, all support elements contain a metal-Si multilayer film, a metal-Ge multilayer film, and / or a chromium nitride layer. In other embodiments, only some of the support elements contain a metal-Si multilayer film, a metal-Ge multilayer film, and / or a chromium nitride layer. In embodiments where only some of the support elements contain a metal-Si multilayer film, a metal-Ge multilayer film, and / or a chromium nitride layer, it is preferable to provide the metal-Si multilayer film, a metal-Ge multilayer film, and / or a chromium nitride layer on the most wear-prone support elements.
[0015] The object holder may be a substrate holder. The object holder may be a wafer holder such as a wafer table, or a wafer clamp such as an electrostatic wafer clamp. The object holder may be a reticle holder such as a reticle clamp or a reticle table. In fact, the substrate holder may be any holder that requires micrometer or nanometer precision in flatness.
[0016] Multiple support elements may be provided with a top coating layer. The material constituting the top coating layer may be a Ti-Si multilayer material, a Mo-Si multilayer material, a Ti-Ge multilayer material, a Mo-Ge multilayer, a chromium nitride layer, or any combination thereof, and may be different from, and it will be understood that different materials are preferred. The top coating layer material may be any known top layer material. The top coating material may be selected from chromium nitride, diamond-like carbon, or a combination thereof. If the top coating comprises chromium nitride, it will be understood that a portion of the top coating may be heat-treated to adjust the shape of the top surface by densifying the material.
[0017] The thickness of the metal-Si multilayer film, metal-Ge multilayer film, and / or chromium nitride layer may be up to approximately 1400 nm, up to approximately 1300 nm, up to approximately 1200 nm, up to approximately 1100 nm, up to approximately 1000 nm, up to approximately 900 nm, up to approximately 800 nm, up to approximately 700 nm, up to approximately 600 nm, up to approximately 500 nm, up to approximately 400 nm, up to approximately 300 nm, up to approximately 200 nm, or up to approximately 100 nm. The thickness of the metal-Si multilayer film, metal-Ge multilayer film, or chromium nitride layer can be selected to provide the desired height adjustment range required for a particular application.
[0018] According to a second aspect of this disclosure, an object table is provided which comprises an object holder according to the first aspect.
[0019] A third aspect of this disclosure provides an optical element for a lithography apparatus. This optical element comprises a metal-Si multilayer film, a metal-Ge multilayer film, or a chromium nitride layer, and is configured such that the shape of these layers is selectively altered by heat treatment of the metal-Si multilayer film, the metal-Ge multilayer film, and / or the chromium nitride layer. As in the first aspect, the metal of the metal-Si multilayer film and / or metal-Ge multilayer film may be selected from titanium, molybdenum, or any combination thereof. This optical element may be a mirror block typically having a mirror surface on the side, in applications of an interferometer-based object table positioning system.
[0020] Previously, it was impossible to correct deformation on the mirror surface after IBF correction and the application of the mirror layer. Such deformation could occur in the mirror layer itself or during the assembly process. This disclosure makes it possible to correct deformation even after the mirror surface has been formed by selectively heating the metal-Si multilayer film, metal-Ge multilayer film, and / or chromium nitride layer.
[0021] A fourth aspect of the present disclosure provides an apparatus for controlling surface flatness, the apparatus comprising an object holder or optical element according to the present disclosure and means for changing the phase configuration of a metal-Si multilayer film, a metal-Ge multilayer film, and / or a chromium nitride layer.
[0022] It will be understood that controlling flatness does not necessarily mean making the surface as flat as possible. This is because it may be necessary to compensate for errors in other parts of the system to which the device is applied by providing a non-flat surface so that the substrate deforms into the desired shape when the substrate engages with the surface.
[0023] The means for changing the phase configuration may be any type of heater, such as an electric heater or a laser. A laser may be preferred due to its high precision.
[0024] According to a fifth aspect of the present disclosure, there is provided a lithography apparatus or tool comprising an object holder according to the first aspect of the present disclosure, an object table according to the second aspect, an optical element according to the third aspect, or an apparatus according to the fourth aspect.
[0025] According to a sixth aspect of the present disclosure, there is provided a method of correcting the flatness of the surface of an object holder or an optical element of a lithography apparatus. The method comprises providing a surface comprising at least one material capable of volume change by heating, and controlling the flatness of the surface by heat treatment of at least one material capable of volume change by heating. Optionally, at least one material capable of volume change by heating is a multilayer film, and optionally, a chromium nitride multilayer film, or a metal-Si multilayer film, or a metal-Ge multilayer film, and optionally, the metal is selected from titanium, molybdenum, or any combination thereof.
[0026] As described above, by providing a phase change material, that is, a metal-Si multilayer film, and / or a chromium nitride layer, and / or a metal-Ge multilayer film on the surface, it becomes possible to control the height of the surface region and to correct the surface shape. Previously, it was impossible to perform this in-situ.
[0027] Correcting the flatness of the surface may be achieved by selectively heating and annealing the material to a predetermined temperature, and optionally may be achieved by laser heating.
[0028] Controlling the flatness of the surface is preferably performed within the lithography apparatus.
[0029] Previously, due to the risk of particle contamination, it was impossible to adjust the surface shape within the lithography apparatus. The present disclosure enables in-situ adjustment of the surface shape by selectively heating a metal-Si multilayer film, a metal-Ge multilayer film, and / or a chromium nitride layer, thus overcoming this drawback.
[0030] According to a seventh aspect of this disclosure, it is provided that an object holder according to a first aspect of this disclosure, an object table according to a second aspect, an optical element according to a third aspect, an apparatus according to a fourth aspect, a lithography apparatus or tool according to a fifth aspect, or a method according to a sixth aspect of this disclosure be used in a lithography method or apparatus.
[0031] The various aspects and features of the present invention described above or below may be combined with various other aspects and features of the present invention, as will be readily understood by those skilled in the art. All such combinations are expressly considered and disclosed herein. [Brief explanation of the drawing]
[0032] Embodiments of the present invention will be described merely as examples with reference to the attached schematic diagrams. [Figure 1] This figure shows a lithography system equipped with a lithography device and a radiation source. [Figure 2] This is a schematic diagram showing a cross-section of the surface relating to this disclosure. [Figure 3] This is a schematic diagram showing the optical element related to this disclosure. [Figure 4] Figures 4(a) to 4(c) show white light interferometry (WLI) images and related data illustrating the change in height of the chromium nitride stack. [Figure 5] Figures 5(a) and (b) show a comparison of atomic force microscope (AFM) images of the chromium nitride surface inside and outside the annealing spot. [Modes for carrying out the invention]
[0033] Figure 1 shows a lithography system comprising a radiation source SO and a lithography apparatus LA. The radiation source SO is configured to generate an EUV radiation beam B and supply the EUV radiation beam B to the lithography apparatus LA. The lithography 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 an object table WT. The object table WT may include an object holder WH configured to support an object W. The object W may be supplied in the form of a substrate. The object table WT may be supplied in the form of a substrate table. The object holder WH may be supplied in the form of a substrate clamp. The substrate may be a wafer.
[0034] The illumination system IL is configured to adjust the EUV radiation beam B before it is incident on the patterning device MA. The illumination system IL may include a faceted field mirror device 10 and a faceted pupil mirror device 11. The faceted field mirror device 10 and the faceted pupil mirror device 11 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 devices in addition to or instead of the faceted field mirror device 10 and the faceted pupil mirror device 11.
[0035] The EUV radiation beam B, after being tuned in this manner, interacts with the patterning device MA. This interaction results in the generation of a patterned EUV radiation beam B'. 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 include several mirrors 13, 14 configured to project the patterned EUV radiation beam B' onto the substrate W held in the substrate table WT. The projection system PS may apply a reduction factor to the patterned EUV radiation beam B' to form an image with features smaller than the corresponding features on the patterning device MA. For example, a reduction factor of 4 or 8 may be applied. In Figure 1, the projection system PS is illustrated to have only two mirrors 13, 14, but the projection system PS may include a different number of mirrors (e.g., six or eight mirrors).
[0036] The substrate W may include a previously formed pattern. In this case, the lithography apparatus LA aligns the image formed by the patterned EUV radiation beam B' with the previously formed pattern on the substrate W.
[0037] A small amount of gas (e.g., hydrogen) at a relative vacuum, i.e., a pressure much lower than atmospheric pressure, may be provided within the radiation source SO, the illumination system IL, and / or the projection system PS.
[0038] The radiation source SO shown in Figure 1 is of a type that could be called, for example, a laser-generated plasma (LPP) source. A laser system LS, for example, including a CO2 laser, is configured to impart energy to a fuel, such as tin (Sn), supplied from a fuel emitter 3, by a laser beam LB. Although tin is mentioned in the following description, any suitable fuel can be used. The fuel may be, for example, a liquid, or it may be, for example, a metal or an alloy. The fuel emitter 3 may include a nozzle configured to guide, for example, tin in the form of droplets along a trajectory toward the plasma-forming region 4. The laser beam LB is incident on the tin in the plasma-forming region 4. The imparting of laser energy to the tin generates a tin plasma 7 in the plasma-forming region 4. Radiation, including EUV radiation, is emitted from the plasma 7 during the de-excitation and recombination of ions and electrons in the plasma.
[0039] EUV radiation from the plasma is collected and focused by a collector 5. The collector 5 comprises, for example, a per-normal incident radiation collector 5 (sometimes more commonly called a normal incident radiation collector). The collector 5 may have a multilayer mirror structure configured to reflect EUV radiation (e.g., EUV radiation having a desired wavelength such as 13.5 nm). The collector 5 may have an ellipsoidal configuration with two foci. The first focal point may be located in the plasma-forming region 4, and the second focal point may be located in an intermediate focal point 6, which will be described later.
[0040] The laser system LS may be spatially separated from the radiation source SO. In this case, the laser beam LB may be transmitted from the laser system LS to the radiation source SO via a beam delivery system (not shown) comprising, for example, a suitable guide mirror and / or beam expander and / or other optical systems. The laser system LS, radiation source SO, and beam delivery system may be considered together as a radiation system.
[0041] The radiation reflected by collector 5 forms EUV radiation beam B. EUV radiation beam B is focused at intermediate focus 6, forming an image of the plasma present in plasma-forming region 4 at intermediate focus 6. The image at intermediate focus 6 functions as a virtual radiation source for illumination system IL. Radiation source SO is positioned such that intermediate focus 6 is located at or near the opening 8 of the surrounding structure 9 of radiation source SO.
[0042] Figure 1 shows the SO radiation source as a laser-generated plasma (LPP) source, but EUV radiation may be generated using any suitable radiation source such as a discharge-generated plasma (DPP) source or a free-electron laser (FEL).
[0043] Figure 2 is a schematic diagram showing a cross-section of a surface relating to this disclosure. A single bar 15 is depicted, but it should be understood that multiple bars may be provided on the surface. The bar 15 comprises a metal-Si multilayer film, such as a Ti-Si multilayer film or a Mo-Si multilayer film 16, and is coated with a coating material 17, such as chromium nitride and / or diamond-like carbon. A metal-Ge multilayer film may be provided alternatively or additionally. It should be understood that the reference to the metal-Si multilayer film also applies to the metal-Ge multilayer film and / or chromium nitride layer. The coating material 17 is depicted surrounding the metal-Si multilayer film 16, but it should be understood that the coating material 17 may be provided only on the top of the metal-Si multilayer film 16.
[0044] During use, the height of individual burrs 15 is controlled by selectively heating and annealing the metal-Si multilayer film 16 that forms at least a portion of the burrs 15. Any suitable heating method can be used, but a laser is preferred in terms of accuracy and precision. A pulsed laser may be used. The heat source may be concentrated on a single burr or a group of burrs. The degree of heating and the cooling rate can be controlled by adjusting the intensity and duration of the laser pulse. By adjusting the intensity and duration of the laser pulse, the height of the burrs 15 can be adjusted to provide a desired surface shape. The change in burr height is stable within the normal operating temperature range of the substrate holder WH (which may be 0°C to 100°C), and phase changes and changes in physical properties are brought about solely by the intended heat source.
[0045] Figure 3 is a schematic diagram showing an optical element 18 according to the present disclosure. The optical element comprises a base layer 19 supporting a metal-Si multilayer film 16. In embodiments, a chromium nitride layer and / or a metal-Ge multilayer film may be provided in addition to or instead of the metal-Si multilayer film. The metal-Si multilayer film supports a mirror layer 20 configured to reflect incident light. By providing a metal-Si multilayer film 16 that can be adjusted by selective heating, the mirror layer 20 on it can be adjusted as needed. Without the metal-Si multilayer film 16, there is no way to change the shape of the mirror layer 20 in a lithography apparatus, because other techniques generate contaminants and / or cannot be performed in a lithography apparatus.
[0046] Figures 4(a)–(c) show white light interferometry (WLI) images illustrating the change in height of a chromium nitride laminate. Each image shows the effect of locally irradiating the surface of a chromium nitride laminate, which comprises a glass layer, a pre-densified chromium nitride layer on top of it, a porous chromium nitride layer on top of that, and a standard-density chromium nitride layer on top of that, with an infrared laser to apply different heat loads at multiple locations, and the corresponding decrease in surface height. The associated graphs show cross-sections along horizontal axis 1 and vertical axis 2. In each graph, the three regions where the height has decreased can be identified by the corresponding dips in the graph lines. Similarly, a single dip moving along the vertical axis corresponds to a single decrease in height along that axis. As can be seen from the figures, the degree of height change depends on the irradiation dose, and adding units of irradiation results in a larger change in height.
[0047] Figures 5(a) and (b) show a comparison of atomic force microscope (AFM) images of the chromium nitride surface inside and outside the annealed spot. As can be seen from the figures, annealing by selective heating does not affect the surface morphology and roughness, and the differences in average roughness and skew are within the range of natural surface variation.
[0048] It will be understood that optical elements used in lithography equipment may already have a chromium nitride layer. Previously, it was not recognized that the surface shape of optical elements could be adjusted by densifying the chromium nitride. Therefore, the method according to the present invention can be used to regenerate existing optical elements, which was previously considered impossible, without using processes that are less sensitive and may generate unwanted particles. Since the method described herein does not generate particles, it is suitable for in-situ use, which was previously impossible. Furthermore, if the heat source is a laser, the laser can also be used to clean surfaces contaminated with particles and / or organic contaminants.
[0049] This disclosure can, in particular, be used to control the surface shape of electrostatic wafer clamps, reticle clamps, vacuum wafer chucks, and mirror blocks.
[0050] It will be understood that references to multiple features may be used interchangeably with references to the singular forms of those features, such as "at least one" and / or "each." The singular forms of features, such as "at least one" or "each," may be used interchangeably.
[0051] Embodiments of the present invention have been described in relation to substrates, substrate holders, and substrate tables, but in other embodiments, the present invention may be used to clamp a mask MA (or other patterning device) to a support structure MT (see Figure 1) of a lithography apparatus, or to clamp other objects.
[0052] While this book may specifically refer to the use of lithography equipment in IC manufacturing, it should be understood that the lithography equipment described herein may have other applications. These other applications include the manufacture of integrated optical systems, induction and detection patterns for magnetic domain memory, flat panel displays, liquid crystal displays (LCDs), and thin-film magnetic heads.
[0053] While embodiments of the present invention may have been specifically mentioned in this book within the context of lithography apparatus, embodiments of the present invention may be used in other apparatuses. Embodiments of the present invention may form part of a mask inspection apparatus, a measuring apparatus, or any apparatus for measuring or processing objects such as wafers (or other substrates) or masks (or other patterning devices). These apparatuses may generally be called lithography tools. Such lithography tools may operate under vacuum or atmospheric (non-vacuum) conditions. An object holder according to one embodiment of the present invention may form part of a lithography tool.
[0054] While specific embodiments of the present invention have been described above, it will be understood that the present invention may be implemented in ways other than those described above. The above description is for illustrative purposes only and not for limitation. Therefore, it will be clear to those skilled in the art that modifications to the described invention may be made without departing from the following claims.
[0055] The aspects of this disclosure are described in the following numbered clauses. (Item 1) An object holder configured to support an object, the object holder comprising a support surface having a plurality of support elements, the plurality of support elements comprising a metal-Si multilayer film, a metal-Ge multilayer film, and / or a chromium nitride layer, and configured so that the individual heights of the plurality of support elements can be selectively changed by heat treatment of the metal-Si multilayer film, the metal-Ge multilayer film, and / or the chromium nitride layer. (Item 2) The object holder according to Item 1, wherein the metal is selected from molybdenum, titanium, or any combination thereof. (Clause 3) The object holder according to Clause 1 or Clause 2, wherein the plurality of support elements are crowbars. (Item 4) The object holder according to any of the above items, wherein the object holder is a wafer clamp, preferably an electrostatic wafer clamp, a wafer table, a reticle table, or a reticle clamp. (Clause 5) The object holder according to any of the above clauses, wherein the plurality of support elements are provided with a top coating material, which optionally is selected from chromium nitride, diamond-like carbon, or a combination thereof. (Item 6) The object holder according to any of the above items, wherein the thickness of the metal-Si multilayer film, metal-Ge multilayer film, and / or chromium nitride layer is up to about 1400 nm, up to about 1300 nm, up to about 1200 nm, up to about 1100 nm, up to about 1000 nm, up to about 900 nm, up to about 800 nm, up to about 700 nm, up to about 600 nm, up to about 500 nm, up to about 400 nm, up to about 300 nm, up to about 200 nm, or up to about 100 nm. (Item 7) The object holder according to any of the above items, wherein the thickness of the layers in the multilayer film is in the range of about 2 nm to about 100 nm, and optionally in the range of about 10 nm to about 20 nm. (Item 8) An object table comprising an object holder as described in any of the above items. (Item 9) An optical element for a lithography apparatus, the optical element comprising a metal-Si multilayer film and / or a metal-Ge multilayer film and / or a chromium nitride layer, configured such that the shape of these layers is selectively changed by heat treatment of the metal-Si multilayer film, the metal-Ge multilayer film and / or the chromium nitride layer, optionally the metal being titanium, molybdenum, or a combination thereof, and optionally the optical element being a mirror or a mirror block. (Item 10) An apparatus for controlling the flatness of a surface, the apparatus comprising an object holder or optical element as described in any of the above items, and means for changing the phase configuration of the metal-Si multilayer film, metal-Ge multilayer film, and / or chromium nitride layer, wherein the means optionally comprises a laser and / or an electric heater. (Clause 11) A lithography apparatus or tool comprising an object holder as described in any of Clauses 1 to 7, an object table as described in Clause 8, an optical element as described in Clause 9, or an apparatus as described in Clause 10. (Item 12) A method for correcting the flatness of the surface of an object holder or optical element of a lithography apparatus, the method comprising: providing a surface comprising a metal-Si multilayer film, a metal-Ge multilayer film, and / or a chromium nitride layer; and controlling the flatness of the surface by heat treatment of the metal-Si multilayer film, a metal-Ge multilayer film, and / or chromium nitride layer, wherein the metal is optionally selected from titanium, molybdenum, or any combination thereof. (Clause 13) The method of Clause 12, wherein the correction of the surface flatness is achieved by selectively heating the material to a predetermined temperature and annealing, and optionally by laser heating. (Clause 14) Controlling the flatness of the surface is performed in a lithography apparatus, as described in Clause 12 or 13. (Clause 15) Use in an object holder as described in any of Clauses 1 to 7, an object table as described in Clause 8, an optical element for a lithography apparatus as described in Clause 9, an apparatus as described in Clause 10, a lithography apparatus or tool as described in Clause 11, or a lithography method or apparatus as described in any of Clauses 12 to 14.
Claims
1. An object holder configured to support an object, The object holder comprises a support surface having a plurality of support elements, The plurality of support elements comprises a metal-Si multilayer film and / or a metal-Ge multilayer film and / or a chromium nitride layer, and is configured so that the individual heights of the plurality of support elements can be selectively changed by heat treatment of the metal-Si multilayer film, the metal-Ge multilayer film and / or the chromium nitride layer. Object holder.
2. The aforementioned metal is selected from molybdenum, titanium, or any combination thereof. The object holder according to claim 1.
3. The aforementioned multiple support elements are crowbars. The object holder according to claim 1 or 2.
4. The object holder is a wafer holder such as a wafer clamp, preferably an electrostatic wafer clamp, or a wafer table, or The object holder is a reticle holder such as a reticle table or a reticle clamp. An object holder according to any one of claims 1 to 3.
5. The plurality of support elements are provided with a top coating material, which is optionally selected from chromium nitride, diamond-like carbon, or a combination thereof. An object holder according to any one of claims 1 to 4.
6. The thickness of the metal-Si multilayer film, metal-Ge multilayer film, and / or chromium nitride layer is at most about 1400 nm, at most about 1300 nm, at most about 1200 nm, at most about 1100 nm, at most about 1000 nm, at most about 900 nm, at most about 800 nm, at most about 700 nm, at most about 600 nm, at most about 500 nm, at most about 400 nm, at most about 300 nm, at most about 200 nm, or at most about 100 nm. An object holder according to any one of claims 1 to 5.
7. The thickness of the multilayer film or the layer is in the range of approximately 2 nm to approximately 100 nm, and optionally in the range of approximately 10 nm to approximately 20 nm. An object holder according to any one of claims 1 to 6.
8. The object holder comprises the object holder according to any one of claims 1 to 7. Object table.
9. An optical element for a lithography apparatus, The optical element comprises a metal-Si multilayer film and / or a metal-Ge multilayer film and / or a chromium nitride layer, and is configured such that the shape of these layers can be selectively changed by heat treatment of the metal-Si multilayer film, the metal-Ge multilayer film and / or the chromium nitride layer. The metal may optionally be selected from titanium, molybdenum, or a combination thereof. Optionally, the optical element is a mirror block. Optical element.
10. A device for controlling the flatness of a surface, wherein the device is An object holder or optical element according to any one of claims 1 to 9, The system includes means for changing the phase configuration of the metal-Si multilayer film, metal-Ge multilayer film, and / or chromium nitride layer, The means comprises a heater, and optionally, the means comprises a laser and / or an electric heater. Device.
11. The apparatus comprises an object holder according to any one of claims 1 to 7, an object table according to claim 8, an optical element according to claim 9, or an apparatus according to claim 10. Lithography equipment or tools.
12. A method for correcting the flatness of the surface of an object holder or optical element of a lithography apparatus, wherein the method is: A surface is provided that comprises at least one material capable of undergoing volume changes due to heating, The method comprises controlling the flatness of the surface by heat treatment of at least one of the materials, which is capable of volume change due to heating, The at least one material capable of volume change by heating is a chromium nitride multilayer film, or a metal-Si multilayer film, or a metal-Ge multilayer film. The metal may optionally be selected from titanium, molybdenum, or any combination thereof. method.
13. Correcting the flatness of the surface is achieved by selectively heating and annealing at least one of the materials to a predetermined temperature, and optionally by laser heating. The method according to claim 12.
14. The method described above comprises correcting the flatness of the surface of the object holder according to any one of claims 1 to 7, The aforementioned surface is a support surface having multiple support elements, and the volume change is achieved by selectively adjusting the height of the support elements. The method according to claim 12 or 13.
15. Controlling the flatness of the aforementioned surface is performed within the lithography apparatus. The method according to any one of claims 12 to 14.
16. Use in an object holder according to any one of claims 1 to 7, an object table according to claim 8, an optical element for a lithography apparatus according to claim 9, an apparatus according to claim 10, a lithography apparatus or tool according to claim 11, or a lithography method or apparatus according to any one of claims 12 to 15.