Pellicles for EUV Lithography

Abstract

A wafer comprising a mask on one face and at least one layer on an opposite face, wherein the mask comprises at least one scribe line, the scribe line overlapping at least a portion of the opposite face that is substantially free of the at least one layer described. Also described is a method of making a pellicle, comprising the steps of providing a wafer comprising a mask on one face and at least one layer on an opposite face; defining a scribe line in the mask; and selectively removing a portion of the at least one layer, the portion at least partially overlapping the scribe line; and a method of making a pellicle, comprising the steps of providing a pellicle core, and removing at least some material from at least one face of the pellicle core in a non-oxidizing environment. In any aspect, the pellicle may comprise a metal nitride layer.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to European application 18170855.3 filed on May 4, 2018, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present invention relates to a wafer, a method for preparing the wafer, a pellicle for a photolithography device comprising the wafer, a method for preparing the pellicle, and a photolithography device comprising the pellicle. 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] The wavelength of radiation used by a lithographic apparatus to project a pattern onto a substrate determines the minimum size of a feature that can be formed on the substrate. A lithographic apparatus using EUV radiation, which is electromagnetic radiation having a wavelength in the range of 4 nm to 20 nm, can be used to form smaller features on a substrate compared to a conventional lithographic apparatus (which may, for example, use electromagnetic radiation having a wavelength of 193 nm).

[0006] The lithographic apparatus includes a patterning device (e.g., a mask or reticle). Radiation is provided by or reflected from the patterning device to form an image on a substrate. A pellicle may be provided to protect the patterning device from suspended or airborne particles and other forms of contaminants. Contaminants on the surface of the patterning device may cause manufacturing defects on the substrate.

[0007] The pellicle may also be provided to protect optical components other than the patterning device. The pellicle may also be used to provide a path for lithographic radiation between sealed regions of the lithographic apparatus. The pellicle may also be used as a filter, such as a spectral purity filter.

[0008] Known pellicles can include, for example, independent membranes, such as silicon pellicles, silicon nitride, graphene or graphene derivatives, carbon nanotubes, or other membrane materials. The mask assembly can include a pellicle that protects the pattern forming device (e.g., mask) from particle contamination. The pellicle can be supported by a pellicle frame to form a pellicle assembly. The pellicle can be attached to the frame, for example, by gluing the pellicle boundary area to the frame. The frame can be permanently attached or releasably attached to the pattern forming device.

[0009] During use, the temperature of the pellicles in lithographic apparatus rises to anywhere from about 500° C. to 1000° C. or higher. These high temperatures can damage the pellicles, and it is therefore desirable to improve ways to dissipate the heat in order to reduce the operating temperature of the pellicles and improve the pellicle lifespan.

[0010] One approach that has been tried is to apply a thin metal film (coating) (e.g., a ruthenium film) to the pellicle. The metal film increases the emissivity of the pellicle and thereby increases the rate at which heat is emitted from the pellicle, thereby causing a decrease in the equilibrium temperature at which the rate at which the pellicle emits heat is the same as the rate at which it absorbs heat. The metal layer is disposed on the face of the core of the pellicle, which may be, for example, a silicon wafer.

[0011] Since the pellicle is present in the optical path of the EUV radiation beam, it is necessary for the pellicle to be as particle-free as possible. This is because the presence of particles may cause imaging defects on the wafer and may also cause hot spots on the pellicle, which may ultimately lead to premature failure of the pellicle. Using existing methods of preparing pellicles including a core and a coating, a relatively large number of particles are generated, which may contaminate the surface of the pellicle.

[0012] It would therefore be desirable to provide a method for producing a pellicle which results in a pellicle having less particle contamination than pellicles produced using prior art techniques; and a pellicle produced according to such a method.

[0013] Furthermore, while the pellicle must be resilient enough to withstand the harsh environment inside the lithographic apparatus, because the pellicle is in the optical path of EUV radiation, it is desirable to reduce the amount of EUV radiation absorbed by the pellicle as this affects the number of wafers that can be imaged in a given period of time.

[0014] It is therefore desirable to provide a pellicle having improved EUV transmittance which also exhibits good performance and can be reliably manufactured.

[0015] Although the present application generally relates to pellicles in the context of lithographic apparatus, and in particular EUV lithographic apparatus, the present invention is not limited only to pellicles and lithographic apparatus, and it will be appreciated that the subject matter of the present invention may be used in any other suitable apparatus or situation.

[0016] For example, the method of the invention may be equally applied to spectral purity filters. Practical EUV sources, such as those using plasma to generate EUV radiation, emit not only desired "in-band" EUV radiation, but also undesired (out-of-band) radiation. This out-of-band radiation is most notably in the deep UV (DUV) radiation range (100 nm to 400 nm). Furthermore, in the case of some EUV sources (e.g. laser-produced plasma EUV sources), the radiation from the laser, typically at 10.6 microns, exhibits significant out-of-band radiation.

[0017] In lithographic equipment, spectral purity is desired for several reasons. One reason is that the resist is sensitive to radiation of out-of-band wavelengths, and therefore the image quality of the pattern applied to the resist may degrade when the resist is exposed to such out-of-band radiation. In addition, infrared radiation of out-of-band radiation, such as the 10.6 micron radiation in some laser-generated plasma sources, causes unwanted and unnecessary heating of the pattern forming device, substrate and optical devices within the lithographic equipment. Such heating may cause damage to these components, degradation of their life and / or defects or deformations in the pattern projected onto and applied to the substrate coated with the resist.

[0018] A typical spectral purity filter may, for example, be formed of a silicon base structure (e.g. a silicon grid, or other member provided with holes) coated with a reflective metal such as molybdenum. In use, a typical spectral purity filter may be subjected to high heat loads from, for example, incident infrared and EUV radiation. The heat load may result in the temperature of the spectral purity filter being above 800°C. Under high heat loads, the coating may delaminate due to differences in the linear expansion coefficients between the reflective molybdenum coating and the underlying silicon support structure. Delamination and degradation of the silicon base structure is accelerated by the presence of hydrogen, which is often used as a gas in environments where spectral purity filters are used in order to inhibit debris (e.g. debris such as particles, etc.) from entering or leaving certain parts of the lithographic apparatus. Therefore, a spectral purity filter may be used as a pellicle, and vice versa. Therefore, references to a "pellicle" in this application also refer to references to a "spectral purity filter". Although reference is primarily made to a pellicle in this application, all features may equally apply to a spectral purity filter.

[0019] In a lithographic apparatus (and / or method), it is desirable to minimize the loss of intensity of radiation being used to apply a pattern to a resist-coated substrate. One reason for this is that ideally, as much radiation as possible should be available for applying the pattern to the substrate, for example to reduce exposure time and increase throughput. At the same time, it is desirable to minimize the amount of undesired radiation (e.g. out-of-band radiation) that passes through the lithographic apparatus and impinges on the substrate. Furthermore, it is desirable to ensure that the spectral purity filter used in the lithographic method or apparatus has a sufficient service life and does not degrade rapidly over time due to high heat loads to which the spectral purity filter may be exposed and / or hydrogen (or the like, such as free radical species, including H* and HO*) to which the spectral purity filter may be exposed. It is therefore desirable to provide an improved (or alternative) spectral purity filter, and for example to provide a spectral purity filter suitable for use in a lithographic apparatus and / or method.

[0020] Furthermore, although this application generally refers to silicon pellicles, it will be appreciated that any suitable pellicle material may be used. For example, the pellicle may include any suitable carbon-based material, including, for example, graphene. Summary of the invention

[0021] The present invention has been made in view of the foregoing problems associated with known methods of making pellicles and pellicles made according to known techniques.

[0022] According to a first aspect of the present invention, there is provided a wafer comprising a mask on one side and at least one layer on an opposite side, wherein the mask comprises at least one scribe line overlapping at least a portion of the opposite side substantially free of the at least one layer.

[0023] Some pellicles are made by depositing a layer of material on the face of a silicon wafer. Portions of the wafer are then selectively removed to produce the final pellicle. The silicon wafer used is circular because this shape is a common shape for silicon wafers (due to the way in which silicon wafers are produced). Due to the constraints of wafer handling equipment, it is desirable to maintain the circular shape as long as possible so that the wafer can be easily manipulated. However, pellicles are usually not circular and therefore need to be shaped to remove excess material. Conventionally, this is done by etching grooves (also known as scribes) in the silicon wafer. Scribes define the edges or peripheries of the pellicle and serve as weak points along which the pellicle can be removed from the remainder of the wafer. For practical reasons, scribes are formed in the same step in which the silicon wafer is etched from below the material on the surface of the silicon wafer to form a "window" through which EUV radiation is transmitted when the pellicle is used in a lithography apparatus. Scribes can be formed in the mask and / or the wafer.

[0024] With current technology, since the etching process does not etch through the material deposited on the surface of the wafer, it is inevitable that the material deposited on the surface of the wafer will bridge the scribe lines. This bridging material is cut in a process known as "slicing". When the excess material is removed from the material that will eventually form the pellicle, the bridging material is disconnected and particulate contamination is generated. These particles can rest on the surface of the pellicle and degrade the performance of the pellicle. Attempts have been made to overcome this problem by disconnecting the bridging material in the presence of a vacuum in order to aspirate any particles that are generated. Attempts have also been made to overcome this problem by protecting the film on the surface of the wafer with a cover. However, both of these other attempts have proven to be unsuccessful.

[0025] It should be understood that the term "stacked" views the wafer as being generally in a horizontal configuration, with the mask located on the lowermost face of the wafer and at least one layer located on the upper face of the wafer. The key feature is that the scribe line and the portion of the opposite face that is substantially free of at least one layer are stacked on each other so that a line generally parallel to the surface of the wafer will pass through both the scribe line and the portion that is substantially free of at least one layer. Thus, at least one layer preferably does not extend across the entirety of the face of the wafer. It should also be understood that the scribe line may be angled relative to the surface of the wafer, i.e., the scribe line may not be perpendicular to the surface of the wafer. In this case, stacking should be understood to mean that portions of the mask that have been removed or otherwise absent and at least one layer are positioned so that the scribe line connects these portions. Thus, when the scribe line is etched through the wafer, the scribe line connects two portions that are substantially free of mask and at least one layer.

[0026] The wafer preferably comprises silicon.

[0027] Silicon is preferably used because it is a well characterized and well defined material in the field of lithography. Silicon also exhibits good EUV transmittance and is able to withstand the conditions within a lithographic apparatus. However, it will be appreciated that other suitable materials may be used and that the invention is not limited to silicon in accordance with the first aspect of the invention. Other suitable materials are suitable materials known to be used in pellicles.

[0028] The mask may comprise a positive resist or a negative resist.Positive resist and negative resist are well known terms in the art of lithography, and any suitable resist may be used.

[0029] In the case where the mask comprises a negative resist, the resist is exposed to radiation which causes the resist to become less soluble in the developer solution. Thus, the pattern of the resist corresponds to the material that will not be removed from the wafer to form the pellicle. Therefore, in the present invention, the mask preferably comprises a negative resist.

[0030] The mask is used to define which parts of the wafer will remain and which parts will be removed in subsequent processing steps. The mask includes at least one scribe line that outlines the perimeter of the pellicle that may ultimately be produced from the wafer. Thus, when a negative resist is used, the scribe line will be substantially free of resist to allow the underlying material to be etched away. In an embodiment, the mask protects a frame of wafer material that supports the material that forms the pellicle itself, which is a layer of material initially deposited on one face of the wafer.

[0031] The at least one layer may include one or more of a diaphragm, a sacrificial layer, and a pellicle layer.

[0032] While some pellicles are simple silicon pellicles, it has been discovered that the performance of the pellicle can be improved by providing one or more materials on the surface of the silicon, or even depositing materials onto the silicon, and then subsequently removing the base silicon to leave only the material deposited on the surface of the silicon wafer to form the portion of the pellicle through which EUV radiation is transmitted.

[0033] The pellicle layer may include at least one of the following: a metal layer, an oxide layer, a nitride layer, a silicide layer, a semi-metal layer, and a non-metal layer. The pellicle layer may include any suitable material that is chemically and / or thermally stable under operating conditions in the lithographic apparatus and allows EUV transmission.

[0034] Suitable metal layers may include molybdenum, zirconium and / or ruthenium. The oxide layer may include silicon dioxide or a metal oxide. The nitride layer may include silicon nitride, silicon oxynitride, carbon nitride, boron nitride or the like. The silicide layer may include a metal silicide, such as molybdenum silicide, ruthenium silicide or zirconium silicide. The non-metallic layer may include carbon in any suitable form, preferably graphene.

[0035] It has been found that the metal nitride layer can provide certain advantages for the final pellicle. The metal nitride layer can include titanium nitride and / or tantalum nitride. The metal nitride layer can have any suitable thickness. It is desirable to maximize the transmittance of the pellicle for radiation used in lithography (e.g., EUV radiation) while still making the pellicle meet other physical requirements suitable for use in a lithography machine (preferably an EUV lithography machine). Therefore, it is preferred for the pellicle to be as thin as possible while also maintaining the necessary physical properties required for the pellicle. The thickness of the metal nitride layer can be between about 0.1 nm and about 6 nm. Preferably, the thickness of the metal nitride layer is less than about 1 nm. The metal nitride can be used as a seed layer. Therefore, the metal nitride can be used as such a layer: another layer that can be called a capping layer is set on the layer. The capping layer can include any suitable material, including ruthenium, molybdenum, boron, zirconium and combinations thereof. The capping layer preferably can include ruthenium. It has been found satisfactorily that the metal nitride layer may result in an increase in the emissivity of the pellicle, thus possibly having the same or better emissivity at the same metal layer thickness or even at a reduced metal layer thickness than previous pellicles. It has also been found satisfactorily that the metal nitride layer reduces or prevents the anti-wetting of an overlapping metal layer (such as ruthenium). This allows the pellicle to withstand higher powers than before while still maintaining its integrity. There is also increased thermal stability, which also provides the pellicle with increased power capability. Another advantage is that the amount of pores in the pellicle layer is reduced, and there is a proportional increase in the surface of the pellicle covered by the metal layer. This prevents oxidation of the base material and thereby reduces the drift of the transmittance of the pellicle over time when in use. It is desirable to avoid changes in the transmittance of the pellicle when in use to allow more consistent imaging of the wafer. In addition, the metal nitride layer can act as a barrier to slow or prevent the formation of metal silicide (caused by the reaction of silicon with the metal layer.) The metal nitride can increase the temperature at which the silicon reacts with the metal in the metal layer to form the metal silicide, and thereby allow the pellicle to operate reliably at higher powers and / or temperatures. The metal nitride layer can be provided by any suitable method known in the art. For example, the metal nitride can be provided by atomic layer deposition or chemical vapor deposition.

[0036] The pellicle layer may be strong enough to form a pellicle without a silicon support layer. Thus, in use, EUV radiation only needs to pass through the pellicle layer and does not need to pass through the silicon layer.

[0037] The sacrificial layer may be a layer that can be easily removed from the wafer without damaging the wafer. The sacrificial layer is preferably removed from the wafer before the wafer is used as a pellicle.

[0038] The wafer may also include a protective layer.

[0039] The protective layer preferably covers at least one layer (i.e., a layer of material deposited on one face of the wafer core). The protective layer acts as a barrier to prevent damage to the at least one layer and as a support for the at least one layer when the wafer is etched away from below. Without the protective layer, if the strength of the at least one layer is not sufficient to support the weight of the silicon wafer, the at least one layer may be damaged and / or the wafer may break along the scribe line.

[0040] The protective layer may include at least one of a polymer, a resist, and a lacquer. It will be appreciated that any suitable protective layer may be used.

[0041] Preferably, the protective layer comprises poly(p-xylene) (parylene). It will be appreciated that any suitable polymer may be used. It is suitable that the polymer is located in a position where it is non-reactive relative to at least one layer on the wafer and can be removed from the wafer without causing damage. For example, the protective layer may be soluble in a solvent that does not dissolve the other materials forming the wafer, or may react with a reactant that does not react with any other material forming the wafer or reacts much more slowly with any of the aforementioned other materials.

[0042] According to a second aspect of the present invention, a method for preparing a surface film is provided, the method comprising the following steps: providing a wafer, the wafer comprising a mask on one side and at least one layer on an opposite side; defining a scribe line in the mask; and selectively removing a portion of the at least one layer that at least partially overlaps the scribe line.

[0043] Due to the limitations of known methods for producing pellicles, there has hitherto been no suitable way of preparing a pellicle which does not result in the generation of particulate contaminants which may undesirably deposit on the surface of the pellicle. The method according to the second aspect of the invention allows the production of a pellicle while minimizing the generation of particles. By selectively removing at least a portion of at least one layer which at least partially overlaps the scribe line, this allows the wafer to be etched away without at least one layer bridging the scribe line. Thus, there is no need to slice or cut material bridging the scribe line and the generation of particles is therefore reduced.

[0044] The mask may be a positive resist or a negative resist, and the scribe lines may be defined in the resist using any suitable photolithography technique.Thus, the scribe lines may be formed in the mask using photolithography.

[0045] At least a portion of at least one layer may be removed by any suitable technique. Preferably, the technique used is etching, more preferably dry etching, but wet etching or a combination of dry and wet etching is also contemplated.

[0046] The method may also include disposing a protective layer over at least a portion of the at least one layer.

[0047] As with the first aspect of the present invention, the protective layer can be used to support the wafer and prevent the wafer from breaking during etching. The protective layer can also protect at least one layer on the wafer that may be damaged by etching.

[0048] At least a portion of the protective layer can be removed to allow excess wafer material to be removed from the pellicle. The protective layer can be removed from substantially the entire wafer, or can be removed substantially along the scribe line to allow excess material of the pellicle to be removed while still maintaining the protective layer and the support on the pellicle.

[0049] The at least one layer may comprise any of the materials described in relation to the first aspect of the present invention. Thus, the surface film may comprise a metal nitride layer. The metal layer may be disposed on the metal nitride layer.

[0050] The protective layer may comprise any of the materials described in relation to the first aspect of the invention.

[0051] According to a third aspect of the present invention, there is provided a method of preparing a pellicle, the method comprising the steps of: providing a pellicle core; and removing at least some material from at least one side of the pellicle core in a non-oxidizing environment.

[0052] It is desirable to provide a pellicle that provides high EUV transmittance while still maintaining the pellicle's ability to withstand harsh conditions within a lithographic apparatus. Current EUV pellicles are very thin (less than about 100 nm) independent diaphragms suspended in a frame. Existing pellicles include a silicon core with additional layers including silicon nitride and molybdenum and / or ruthenium. Although the additional layers are used to increase the life of the pellicle, the cost is reduced EUV transmittance and increased imaging effects, primarily due to EUV reflection. Efforts are made to make the pellicle as robust as possible to ensure that trouble-free occurrences occur. However, it is expensive to manufacture highly complex pellicles, and it is necessary to reduce the effects on pellicle imaging and increase EUV transmittance in order to allow high throughput via lithographic equipment. Reference to the pellicle may also be considered to include a reference to a wafer. Therefore, the pellicle produced according to the method of the third aspect of the present invention may be a wafer in the first and second aspects of the present invention.

[0053] It has been found that a native oxide layer that occurs between the pellicle core and the capping layer is one cause of EUV transmission loss. Although efforts have been made to reduce the thickness of this layer, these efforts have not been successful and it has not been proven possible to eliminate the native oxide layer.

[0054] In the method according to the third aspect of the invention, the native oxide layer is removed when the core of the pellicle is in a non-oxidizing environment (such as in a vacuum) to avoid regeneration of the native oxide layer. The non-oxidizing environment may be substantially free of any oxygen. It may contain a non-reactive gas, such as an inert gas or nitrogen, or may include hydrogen. The gas is preferably at low pressure.

[0055] The method may include removing at least a portion of the native oxide layer.The method may also alternatively or additionally include thinning the pellicle core material.

[0056] By removing the native oxide layer, the pellicle has greater EUV transmittance and the surface on which the capping layer is subsequently deposited is more uniform, resulting in a more uniform layering of the capping material. Additionally, thinning the pellicle core has the same benefits and also further reduces the overall thickness of the final pellicle.

[0057] The method may also include depositing a cover layer on at least one side of the pellicle.

[0058] The capping layer may be any of the following: a material as described with respect to the first aspect of the invention, or any other suitable capping material. A metal nitride layer as described herein may be provided prior to depositing the capping layer. As described above, the presence of a metal nitride layer may provide a number of advantages to the final surface film.

[0059] The cover layer provides improved properties of the membrane. For example, the cover layer can increase the rate at which the membrane radiates heat, thereby reducing the operating temperature of the membrane.

[0060] The material may be removed from the pellicle by any suitable means. Preferably, the material is removed by etching. Etching may be dry etching, wet etching, or a combination of the two. Dry etching may include sputtering of the silicon oxide layer. For example, an ion beam of an inert gas may be directed onto the undesired silicon oxide layer to remove the layer from the surface. Sputtering may continue to thin the core of the pellicle. Alternatively or in addition, etching may be performed using a process such as C x F y Gases such as etchants (as known in the art) are used.

[0061] To prevent oxidation or other contamination, the cover layer is deposited under vacuum. This reduces the risk of contaminants being trapped between the pellicle core and the cover layer, which could weaken the final pellicle. Therefore, the etching step and the deposition step are preferably performed without the pellicle leaving the non-oxidizing environment. By keeping the pellicle in a non-oxidizing environment, this avoids the regeneration of the oxide layer on the surface of the pellicle core.

[0062] According to a fourth aspect of the present invention, there is provided a pellicle for a lithographic apparatus, the pellicle comprising a silicon core and one or more capping layers, wherein the pellicle is substantially free of an oxide layer between the silicon core and the one or more capping layers.

[0063] Having a surface film that does not include a native oxide layer, thereby producing a surface film with improved transmittance and improved uniformity of the coverage layer. This provides a more predictable and reproducible surface film. The oxide layer removed is preferably silicon oxide.

[0064] The pellicle according to the fourth aspect of the invention may comprise any of the materials described in relation to the first aspect of the invention.

[0065] Therefore, the surface film according to the fourth aspect of the present invention may include a metal nitride layer. The metal nitride layer may include ruthenium, molybdenum, boron, zirconium, titanium, tantalum or a combination thereof. Preferably, the metal nitride layer includes at least one of titanium nitride and tantalum nitride.

[0066] According to a fifth aspect of the present invention, a pellicle for a lithography device is provided, the pellicle comprising a wafer according to the first aspect or the fourth aspect of the present invention, or manufactured by a method according to the second aspect, the third aspect or the seventh aspect of the present invention.

[0067] According to a sixth aspect of the present invention, there is provided use of the pellicle according to any one of the first to fifth and seventh aspects of the present invention in a lithography device.

[0068] According to a seventh aspect of the present invention, there is provided a surface film comprising at least one metal nitride layer.

[0069] As described above, the presence of a metal nitride layer provides several advantages over surface films that do not include such a layer.

[0070] The at least one metal nitride layer may include ruthenium, molybdenum, boron, zirconium, titanium, tantalum or a combination thereof. Preferably, the at least one metal nitride layer includes titanium nitride or tantalum nitride.

[0071] At least one metal nitride layer may have any suitable thickness. The thickness of at least one metal nitride layer may be from about 0.1 nm to about 6 nm. Preferably, the thickness of at least one metal nitride layer is less than about 1.5 nm. In other pellicles, a metal layer (e.g., molybdenum) may be provided below the capping layer. The metal nitride layer may partially or completely replace the molybdenum layer. Due to the advantageous properties provided by the metal nitride layer, the metal nitride layer may be thinner than the layer provided in the equivalent position in other pellicles. In addition, in the case where the metal nitride layer is oxidized during use, the resulting oxide layer is much thinner than the oxide layer produced by oxidation of the original layer thicker than the metal nitride layer. This will reduce the change in the transmittance of the pellicle over time, which is desirable. For example, if a metal layer (such as a molybdenum layer) is replaced by a metal nitride (e.g., titanium nitride) that is thinner than the molybdenum layer, the transmittance of the resulting pellicle will increase, the observed change in EUV transmittance during use will be reduced, and the pellicle will be able to withstand higher powers or temperatures.

[0072] The pellicle may include a metal capping layer disposed on at least one metal nitride layer. The metal capping layer may include ruthenium, molybdenum, boron, zirconium, titanium, tantalum or a combination thereof. Preferably, the metal capping layer includes ruthenium.

[0073] The metal capping layer may have any suitable thickness. The metal capping layer may have a thickness of about 0.1 nm to about 6 nm.

[0074] The pellicle may include one or more other layers known in the art.The pellicle may include a frame supporting the pellicle membrane.

[0075] It should be understood that the first to seventh aspects of the present invention can be combined into any combination, and the features described in relation to one aspect can be combined with the features described in relation to another aspect of the present invention. For example, a wafer produced according to the method of the third aspect of the present invention can be used in the method of the second aspect of the present invention. Similarly, a wafer according to the first aspect of the present invention may include a wafer formed according to the third aspect of the present invention. In other words, the wafer according to the first aspect of the present invention may be substantially free of a native oxide layer between the wafer and at least one layer that may be a covering layer. In an example, any of the methods or apparatuses of any aspect of the present invention may include a step of providing a metal nitride layer or have a metal nitride layer, respectively. In addition, the advantages associated with the features described in relation to one aspect of the present invention also apply to other aspects of the present invention.

[0076] In summary, the method of the present invention allows the manufacture of pellicles that have more predictable and reproducible performance than previous pellicles. The resulting pellicles are suitable for use in lithographic equipment, such as, for example, EUV lithographic equipment. Such pellicles have not been previously possible to manufacture. The pellicles manufactured according to the method of the present invention are able to resist the high temperatures reached when using the pellicles, and also resist attack by free radical species or other reactive species due to the coating material layer on either side of the pellicle. In addition, in embodiments where the method includes providing a metal nitride layer or the pellicle includes a metal nitride layer, the final pellicle benefits from the advantages of having such a layer as described herein.

[0077] The invention will now be described with reference to silicon-based pellicles. However, it will be appreciated that the invention is not limited to silicon-based pellicles and is equally applicable to spectral purity filters and core materials other than silicon. BRIEF DESCRIPTION OF THE DRAWINGS

[0078] Embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings, in which:

[0079] - Figure 1 depicts a lithographic system including a lithographic apparatus and a radiation source according to an embodiment of the present invention;

[0080] - Figure 2 depicts a schematic diagram of a pellicle of the prior art;

[0081] - Figure 3a to Figure 3d Describes the pellicle and method according to the first and second aspects of the invention;

[0082] - Figure 4 Describing the prior art method of covering the core of the pellicle; and

[0083] - Figure 5a and Figure 5b Films and methods according to third and fourth aspects of the invention are depicted. DETAILED DESCRIPTION

[0084] Figure 1A lithography system according to an embodiment of the invention is shown, the lithography system comprising a pellicle 15 according to the second, fourth, fifth and seventh aspects of the invention, or a pellicle 15 manufactured by the method of the first or third aspects of the invention. The lithography system comprises a radiation source SO and a lithography apparatus LA. The radiation source SO is configured to generate an extreme ultraviolet (EUV) radiation beam B. The lithography apparatus LA comprises an illumination system IL, a support structure MT configured to support a pattern forming device MA (e.g., a mask), a projection system PS and a substrate table WT configured to support a substrate W. The illumination system IL is configured to condition the radiation beam B before the radiation beam B is incident on the pattern forming device MA. The projection system is configured to project the radiation beam B (now patterned by the mask MA) onto the substrate W. The substrate W may include a previously formed pattern. In this case, the lithography apparatus aligns the patterned radiation beam B with the pattern previously formed on the substrate W. In such an embodiment, the pellicle 15 is depicted in the path of the radiation and protects the pattern forming device MA. It will be appreciated that the pellicle 15 may be located in any desired position and may be used to protect any of the mirrors in a lithographic apparatus.

[0085] The radiation source SO, the illumination system IL and the projection system PS may all be constructed and arranged so that they may be isolated from the external environment. A gas (e.g., hydrogen) at a pressure below atmospheric pressure may be provided in the radiation source SO. A vacuum may be provided in the illumination system IL and / or the projection system PS. A small amount of gas (e.g., hydrogen) at a pressure far below atmospheric pressure may be provided in the illumination system IL and / or the projection system PS.

[0086] Figure 1 The radiation source SO shown in FIG. 1 is of a type that may be referred to as a laser produced plasma (LPP) source. The laser (which may be, for example, a CO 2 A laser is arranged to deposit energy via a laser beam into a fuel, such as tin (Sn), provided from a fuel emitter. 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 may include a nozzle configured to direct tin, for example in the form of droplets, along a trajectory toward a plasma formation region. The laser beam is incident on the tin at the plasma formation region. The deposition of laser energy into the tin generates a plasma at the plasma formation region. Radiation, including EUV radiation, is emitted from the plasma during de-excitation and recombination of ions of the plasma.

[0087] EUV radiation is collected and focused by a near normal incidence radiation collector (sometimes more generally referred to as a normal incidence radiation collector). The collector may have a multilayer structure arranged to reflect EUV radiation (e.g., EUV radiation having a desired wavelength such as 13.5 nm). The collector may have an elliptical configuration, having two elliptical foci. The first focus may be at the plasma formation region, and the second focus may be at an intermediate focus, as discussed below.

[0088] The laser may be separate from the radiation source SO. In this case, the laser beam may be transferred from the laser to the radiation source SO by means of a beam delivery system (not shown) comprising, for example, suitable directional mirrors and / or beam expanders and / or other optical devices. The laser and the radiation source SO may be considered together as a radiation system.

[0089] The radiation reflected by the collector forms a radiation beam B. The radiation beam B is focused at a point to form an image of the plasma formation region, which serves as a virtual radiation source for illuminating the system IL. The point at which the radiation beam B is focused may be referred to as an intermediate focus. The radiation source SO is arranged so that the intermediate focus is located at or near an opening in the enclosure of the radiation source.

[0090] A radiation beam B is transferred from a radiation source SO to an illumination system IL which is configured to condition the radiation beam. 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 together provide a radiation beam B having a desired cross-sectional shape and a desired angular distribution. The radiation beam B is transferred from the illumination system IL and is incident on a patterning device MA held by a support structure MT. The patterning device MA reflects and patterns the radiation beam B. In addition to the faceted field mirror device 10 and the faceted pupil mirror device 11, or instead of the faceted field mirror device 10 and the faceted pupil mirror device 11, the illumination system IL may also include other mirrors or devices.

[0091] After reflection from the patterning device MA, the patterned radiation beam B enters the projection system PS. The projection system comprises a plurality of mirrors 13, 14 configured to project the radiation beam B onto a substrate W held by a substrate table WT. The projection system PS may apply a reduction factor to the radiation beam so as to form an image in which features are smaller than corresponding features on the patterning device MA. For example, a reduction factor of 4 may be applied. Although in Figure 1 The projection system PS has two mirrors 13, 14, but the projection system may comprise any number of mirrors (eg six mirrors).

[0092] Figure 1The radiation source SO shown in FIG. 1 may include components not shown. For example, a spectral filter may be provided in the radiation source. The spectral filter may substantially transmit EUV radiation but substantially block radiation of other wavelengths, such as infrared radiation.

[0093] Figure 2a A schematic depiction of a cross section of a pellicle produced according to a prior art method is shown. In this figure, the silicon support has been etched away to separate the border 18 and the wafer holder 19 by a scribe line 16. The scribe line 16 is bridged by the cover layer 17. Therefore, in order to release the border 18 from the wafer holder 19, it is necessary to break or cut the cover layer 17 bridging the scribe line 16, which may result in the generation of unwanted particles that may contaminate the cover layer 17.

[0094] Figure 2b Shown in Figure 2a Schematic plan view of the pellicle shown in FIG. Boundary 18 is shown as a phantom line within scribe line 16. It should be understood that scribe line 16 will not be visible due to the presence of cover layer 17, but is shown for clarity. Boundary 18 of the silicon wafer acts as a frame around cover material 17 to support the cover material 17 when used as a pellicle.

[0095] Figure 3a A wafer according to the present invention is depicted, comprising a wafer 23, a capping layer (at least one layer) 17, a scribe line 16, and a mask 20. The capping layer 17 is continuous across the surface of the wafer 23, and the mask 20 on the opposite side of the wafer 23 defines the scribe line 16. The capping layer 17 may include a metal nitride layer (not shown). The capping layer 17 may include a metal layer and a metal nitride layer disposed between the metal layer and the wafer 23. As described above, it has been found that the presence of the metal nitride layer has a number of benefits.

[0096] Figure 3b The wafer is depicted after a portion 27 of cover layer 17 that overlaps scribe line 16 has been removed. Arrow 21 indicates how at least a portion of gap 27 in cover layer 17 overlaps at least a portion of scribe line 16.

[0097] exist Figure 3c In FIG. 2 , a protective layer 22 has been applied to the wafer and the wafer 23 has been etched away where it is not protected by the mask 20. The etching process does not remove the protective layer 22. Crucially, there is no capping material 17 bridging the scribe lines 16.

[0098] like Figure 3c As shown in , the protective layer 22 may have a protruding portion 28 extending into the gap 27 .

[0099] exist Figure 3dIn the embodiment shown in FIG. 1 , the protective layer 22 has been removed and the excess material has been removed to achieve the pellicle. The remaining material from the wafer 23 is used as a frame to support the cover material 17 when used as a pellicle. It should be understood that these figures are not drawn to scale and are only used to illustrate the different layers in the pellicle rather than their corresponding dimensions.

[0100] Figure 4 Schematic diagram depicting a pellicle according to the prior art. The core material comprises a core of a wafer 23 covered by a native oxide layer 24. When a cover layer 25 is deposited on the wafer, the native oxide layer 24 is located between the wafer 23 and the cover layer 25.

[0101] Figure 5a Describe and Figure 4 23, but the native oxide layer is removed from the wafer 23 in a non-oxidizing atmosphere or vacuum 26. The capping layer is deposited on the core while still in the non-oxidizing atmosphere or vacuum 26, which produces a surface film that does not include the native oxide layer. Once the native oxide layer has been removed, a metal nitride layer (not shown) can be disposed on the core layer. The metal capping layer can then be disposed on the metal nitride layer. The metal nitride layer and the metal layer can include any metal described with respect to any aspect of the present invention.

[0102] Figure 5b Similar to Figure 5a , but depicts the following situation: the native oxide layer 24 is removed and the wafer 23 has been thinned, thereby producing a pellicle that is thinner and has better transmittance than the existing pellicle. The cover layer 25 is deposited after the native oxide layer has been removed and / or when the pellicle core has been thinned. In addition, once the native oxide layer has been removed and / or the pellicle core has been thinned, a metal nitride layer can be provided. In this way, there can be a metal nitride layer disposed between the wafer 23 and the cover layer 25. The removal of the native oxide layer and a portion of the pellicle core and the subsequent deposition of the cover layer are performed in a non-oxidizing environment.

[0103] Embodiments of the present invention may also be described as expressed in the following aspects: 1) A chip comprising a mask on one side and at least one layer on an opposite side, wherein the mask comprises at least one scribe line overlapping at least a portion of the opposite side that is substantially free of the at least one layer.

[0104] 2) A wafer according to aspect 1, wherein the wafer comprises silicon.

[0105] 3) A wafer according to aspect 1 or 2, wherein the mask comprises a positive resist or a negative resist.

[0106] 4) A wafer according to any one of aspects 1 to 3, wherein the at least one layer comprises one or more of a diaphragm, a sacrificial layer and a pellicle layer.

[0107] 5) A chip according to aspect 4, wherein the surface film layer includes at least one of a metal layer, an oxide layer, a nitride layer, a silicide layer, a semi-metal layer, a non-metal layer and a metal nitride layer, preferably, wherein the metal layer and / or the metal nitride layer includes ruthenium, molybdenum, boron, zirconium, titanium, tantalum or a combination thereof.

[0108] 6) A wafer according to any one of aspects 1 to 5, wherein the wafer further comprises a protective layer.

[0109] 7) A wafer according to aspect 6, wherein the protective layer is arranged above the at least one layer, and the at least one layer is arranged between the protective layer and a mask.

[0110] 8) A wafer according to aspect 7, wherein the protective layer has a protruding portion extending into a gap, the gap being formed in the at least one layer at a location where the portion of the opposing surface is substantially free of the at least one layer.

[0111] 9) A wafer according to any one of aspects 6 to 8, wherein the protective layer comprises at least one of a polymer, a resist and a lacquer, preferably, wherein the polymer is poly(p-xylene).

[0112] 10) A component comprising a wafer, a mask disposed on one side of the wafer, and at least one layer disposed on an opposite side of the wafer, wherein the mask comprises at least one scribe line overlapping at least a portion of the opposite side that is substantially free of the at least one layer.

[0113] 11) The assembly of clause 10, wherein the wafer comprises silicon.

[0114] 12) An assembly according to clause 10 or 11, wherein the mask comprises a positive resist or a negative resist.

[0115] 13) A component according to any one of aspects 10 to 12, wherein the at least one layer comprises one or more of a diaphragm, a sacrificial layer and a pellicle layer.

[0116] 14) A component according to aspect 13, wherein the surface film layer includes at least one of a metal layer, an oxide layer, a nitride layer, a silicide layer, a semi-metal layer, a non-metal layer and a metal nitride layer, optionally, wherein the metal layer and / or the metal nitride layer includes ruthenium, molybdenum, boron, zirconium, titanium, tantalum or a combination thereof.

[0117] 15) The component according to any one of aspects 10 to 14, wherein the component further comprises a protective layer.

[0118] 16) An assembly according to clause 15, and wherein the at least one layer is arranged between a protective layer and the wafer.

[0119] 17) A component according to aspect 16, wherein the protective layer has a protruding portion extending into a gap formed in the at least one layer at the portion of the opposing surface substantially free of the at least one layer.

[0120] 18) The assembly according to any one of aspects 10 to 18, wherein the protective layer comprises at least one of a polymer, a resist and a lacquer, preferably wherein the polymer is poly(p-xylene).

[0121] 19) A method for preparing a pellicle, comprising the steps of: providing a wafer comprising a mask on one side and at least one layer on an opposite side; defining a scribe line in the mask; and selectively removing a portion of the at least one layer that at least partially overlaps the scribe line.

[0122] 20) A method according to aspect 19, wherein the method further comprises providing a protective layer over at least a portion of the at least one layer.

[0123] 21) A method according to aspect 19, wherein the method further comprises providing a protective layer over at least a portion of the at least one layer, such that the at least a portion of the at least one layer is arranged between the protective layer and the mask.

[0124] 22) A method according to aspect 20 or 21, wherein the protective layer is provided with a protruding portion extending into a gap formed by the selective removal of portions of the at least one layer.

[0125] 23) A method according to any one of aspects 19 to 22, further comprising etching at least a portion of the wafer.

[0126] 24) The method according to aspect 23 further comprises removing at least a portion of the protective layer.

[0127] 25) A method according to any one of aspects 19 to 24, wherein the scribe line and / or the mask are defined by photolithography.

[0128] 26) A method according to any one of aspects 19 to 25, wherein the at least one layer comprises one or more of a diaphragm, a sacrificial layer and a pellicle layer.

[0129] 27) A method according to any one of clauses 23 to 26, wherein the etching is dry etching, wet etching or a combination of the two.

[0130] 28) A method according to any one of aspects 19 to 27, wherein the protective layer comprises at least one of a polymer, a resist and a lacquer.

[0131] 29) A method according to aspect 28, wherein the protective layer comprises poly(p-xylene). 30) A method of preparing a pellicle, the method comprising the steps of: providing a pellicle core; and removing at least some material from at least one side of the pellicle core in a non-oxidizing environment. 31) A method according to aspect 30, wherein the method further comprises depositing a capping layer on at least one side of the pellicle, preferably wherein the capping layer comprises a metal nitride layer and / or a metal layer.

[0132] 32) A method according to clause 30 or 31, wherein the material is removed by etching.

[0133] 33) A method according to clause 32, wherein the etching is dry etching, wet etching or a combination of both.

[0134] 34) A method according to aspects 32 or 33, wherein the etching is achieved by directing an ion beam of an inert gas onto the surface of the pellicle core.

[0135] 35) A method according to any one of aspects 31 to 34, wherein the cover layer is deposited under vacuum.

[0136] 36) A method according to any one of aspects 30 to 35, wherein the non-oxidizing environment is a vacuum.

[0137] 37) A pellicle for a lithographic device, the pellicle comprising a silicon core and one or more. 38) A pellicle for a lithographic device, the pellicle being manufactured by a method according to aspects 19 to 36, or comprising a wafer according to any one of aspects 1 to 9, or a component according to any one of aspects 10 to 18 or aspect 37.

[0138] 39) Use of a pellicle manufactured according to the method described in aspects 19 to 36, or use of a pellicle according to any one of aspects 1 to 18 or aspect 37 in a lithography device.

[0139] 40) A pellicle for a lithographic device, wherein the pellicle comprises at least one metal nitride layer.

[0140] 41) The pellicle according to aspect 40, wherein the at least one metal nitride layer comprises at least one of titanium nitride and tantalum nitride.

[0141] Although specific embodiments of the present invention have been described above, it will be appreciated that the present invention may be practiced in other ways different from those described. The above description is intended to be illustrative rather than restrictive. Therefore, it will be appreciated by those skilled in the art that the described invention may be modified without departing from the scope of the claims set forth below.

[0142] A capping layer, wherein the pellicle is substantially free of an oxide layer between the silicon core and the one or more capping layers.

Claims

1. A component comprising a wafer, a mask disposed on one side of the wafer, and at least one layer disposed on an opposite side of the wafer, wherein the mask comprises at least one scribe line configured to outline the perimeter of a pellicle generated from the wafer, the at least one scribe line overlapping at least a portion of the opposite side that is substantially free of the at least one layer, so that when the component is separated at the at least one scribe line and the portion of the opposite side, there is substantially no overhanging portion of the at least one layer in the adjacent empty space at the separation.

2. The assembly of claim 1, wherein the wafer comprises silicon.

3. An assembly according to claim 1 or 2, wherein the mask comprises a positive resist or a negative resist.

4. The assembly of claim 1 or 2, wherein the at least one layer comprises one or more of a diaphragm, a sacrificial layer, and a pellicle layer. 5 . The component according to claim 4 , wherein the surface film layer comprises at least one of a metal layer, an oxide layer, a nitride layer, a silicide layer, a semi-metal layer, a non-metal layer, and a metal nitride layer. 6 . The assembly of claim 5 , wherein the metal layer and / or the metal nitride layer comprises ruthenium, molybdenum, boron, zirconium, titanium, tantalum or a combination thereof.

7. The assembly of claim 1 or 2, wherein the assembly further comprises a protective layer.

8. The assembly of claim 7, and wherein the at least one layer is arranged between the protective layer and the wafer.

9. The assembly according to claim 8, wherein the protective layer has a protruding portion extending into a gap formed in the at least one layer at the portion of the opposing surface substantially free of the at least one layer.

10. The assembly of claim 7, wherein the protective layer comprises at least one of a polymer, a resist, and a lacquer.

11. The assembly of claim 10, wherein the polymer is parylene.

12. A method for preparing a surface film, comprising the following steps: There is provided an assembly according to any one of claims 1 to 11, the assembly comprising a wafer, a mask disposed on one side and at least one layer disposed on an opposite side; scribe lines are defined in the mask; and selectively removing a portion of the at least one layer that at least partially overlaps the scribe line.

13. The method according to claim 12, wherein: The method also includes disposing a protective layer over at least a portion of the at least one layer.

14. The method according to claim 12, wherein: The method also includes providing a protective layer over at least a portion of the at least one layer such that the at least a portion of the at least one layer is disposed between the protective layer and the mask.

15. A method according to claim 13 or 14, wherein the protective layer is provided with protruding portions extending into gaps formed by the selectively removed portions of the at least one layer.

16. The method of any one of claims 12 to 14, further comprising etching at least a portion of the wafer.

17. The method of claim 16, further comprising removing at least a portion of the protective layer.

18. The method according to any one of claims 12 to 14, wherein the scribe line and / or the mask are defined by photolithography.

19. The method of any one of claims 12 to 14, wherein the at least one layer comprises one or more of a membrane, a sacrificial layer, and a pellicle layer.

20. The method of claim 16, wherein the etching is dry etching, wet etching, or a combination of dry etching and wet etching.

21. The method of any one of claims 12 to 14, wherein the protective layer comprises at least one of a polymer, a resist, and a lacquer.

22. The method of claim 21, wherein the protective layer comprises parylene.

23. A method for preparing a surface film, comprising the following steps: Providing a core material covered with a native oxide layer, removing at least some material from at least one face of the core in a non-oxidizing environment to remove the native oxide layer; and providing an assembly according to any one of claims 1 to 11.

24. The method according to claim 23, wherein: The method also includes depositing a cover layer on at least one face of the core.

25. The method of claim 24, wherein the capping layer comprises a metal nitride layer and / or a metal layer.

26. A method according to claim 23 or 24, wherein the material is removed by etching.

27. The method of claim 26, wherein the etching is dry etching, wet etching, or a combination of dry etching and wet etching.

28. The method of claim 26, wherein the etching is accomplished by directing an ion beam of an inert gas onto the surface of the core.

29. The method of claim 24, wherein the capping layer is deposited under vacuum.

30. The method of any one of claims 23 to 24, wherein the non-oxidizing environment is a vacuum.

31. A pellicle for a lithographic apparatus, the pellicle comprising a core and one or more capping layers, wherein the pellicle is substantially free of an oxide layer between the core and the one or more capping layers, The surface film is manufactured by the method according to any one of claims 23 to 30.

32. A pellicle for a lithographic apparatus, the pellicle being manufactured by the method according to any one of claims 12 to 30, or the pellicle comprising or coming from the assembly according to any one of claims 1 to 11 or the pellicle according to claim 31.

33. Use of a pellicle manufactured by the method of any one of claims 12 to 30, or use of an assembly according to any one of claims 1 to 11 or a pellicle according to claim 31 in a lithographic apparatus.

34. A pellicle for a photolithography device, wherein: The pellicle comprises at least one metal nitride layer, wherein the pellicle is manufactured by the method according to any one of claims 23 to 30.

35. The pellicle of claim 32, wherein the at least one metal nitride layer comprises at least one of titanium nitride and tantalum nitride.

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