Method for manufacturing a membrane assembly

Abstract

A method for manufacturing a membrane assembly for EUV lithography is provided, wherein a layer forming at least a portion of a pellicle membrane is provided after one or more etching steps that define a pellicle boundary for holding the pellicle membrane. Additionally, a pellicle substrate comprising a stack having a front and a back surface is provided, wherein one or more layers on the back surface of the stack are optionally removed to define a pellicle boundary region for holding the pellicle membrane before a layer forming at least a portion of the pellicle membrane is provided.

Description

Technology Field

[0001] Cross-reference regarding related applications

[0002] This application claims priority to EP application 18214904.7 filed on December 20, 2018, the full text of which is incorporated herein by reference.

[0003] Technology field

[0004] The present invention relates to a method for manufacturing a membrane assembly and a membrane assembly precursor. The present invention is used particularly, but not exclusively, in connection with EUV lithography apparatus and EUV lithography tools. Background Technology

[0005] A lithography device is a machine configured to apply a desired pattern onto a substrate. A lithography device can be used, for example, in the manufacture of integrated circuits (ICs). A lithography device can project a pattern from a patterning device (e.g., a mask) onto a radiation-sensitive material (resist) layer provided on a substrate, for example.

[0006] To project a pattern onto a substrate, a lithography device may use electromagnetic radiation. The wavelength of this radiation determines the minimum size of features that can be formed on the substrate. A lithography device using extreme ultraviolet (EUV) radiation with a wavelength in the range of 4 to 20 nm, for example 6.7 nm or 13.5 nm, may be used to form smaller features on a substrate than a conventional lithography device (for example, which may use electromagnetic radiation with a wavelength of 193 nm).

[0007] A patterning device (e.g., a mask or reticle) can be used to apply a pattern to the radiation beam of a lithography device. The radiation is provided through the patterning device or reflected from the patterning device to form an image on a substrate. Contamination on the surface of the patterning device can cause manufacturing defects on the substrate. A membrane assembly, also referred to as a pellicle, may be provided to protect the patterning device from airborne particles and other forms of contamination.

[0008] Pellicles may also be provided to protect optical components other than patterning devices. Pellicles may also be used to provide a path for lithography radiation between regions of a lithography device that are sealed to each other. Pellicles may also be used as radiation filters, such as spectral purity filters, or as part of a dynamic gas lock of a lithography device.

[0009] The use of pellicles in lithography is well known and well established. A pellicle within a lithography device is a membrane (also referred to as a pellicle membrane) located away from the patterning device and situated outside the focal plane of the lithography device when in use. Because the pellicle is located outside the focal plane of the lithography device, contaminant particles landing on the pellicle are also out of focus within the lithography device. Consequently, images of the contaminant particles are not projected onto the substrate. Without a pellicle, contaminant particles landing on the patterning device would be projected onto the substrate and cause defects in the projected pattern.

[0010] A mask assembly may include a pellicle that protects a patterning device (e.g., a mask) from particle contamination. A pellicle membrane may be supported by a pellicle boundary to form a pellicle assembly or a membrane assembly. The pellicle may be attached to a pellicle frame, for example, by bonding a pellicle edge to the pellicle frame or otherwise attaching it. The pellicle frame may be attached to the patterning device permanently or detachably. The pellicle membrane may also be known as a pellicle layer. The pellicle membrane is manufactured starting from a stack comprising at least a substrate and a layer deposited on the substrate.

[0011] For example, due to the thinness of the membrane, it is difficult to manufacture a pellicle membrane or pellicle assembly without the membrane assembly being deformed or damaged during the process. Damage to the membrane assembly or defects in the membrane assembly can result in reduced performance, reduced lifespan, or even failure, which is undesirable. It is desirable to provide a method for manufacturing a pellicle membrane that provides a pellicle with improved yield and / or strength and minimizes damage or defects to the membrane assembly.

[0012] Furthermore, manufacturing a pellicle assembly is time-consuming. Therefore, it is desirable to provide a method for manufacturing a pellicle that allows for the rapid manufacturing of the pellicle assembly or has a reduced cycle time compared to existing methods.

[0013] Although this application generally refers to pellicles in the context of lithography devices, particularly EUV lithography devices, the invention is not limited to pellicles and lithography devices alone, and it is understood that the technical concept of the invention may be used in any other suitable devices or situations. Furthermore, the invention is not specifically limited to EUV lithography and may also be used in lithography using radiation of a longer wavelength than EUV, preferably a shorter wavelength.

[0014] Due to the presence of the pellicle within the optical path of the EUV radiation beam, it is necessary for the pellicle to have high EUV transmittance. High EUV transmittance allows for a larger proportion of incident radiation passing through the pellicle. Additionally, reducing the amount of EUV radiation absorbed by the pellicle can lower the operating temperature of the pellicle. Since transmittance depends at least partially on the thickness of the pellicle, it is desirable to provide a pellicle that is as thin as possible while being reliably strong enough to withstand the sometimes hostile environment within the lithography device. The fact that the desired properties of the pellicle are as thin as possible implies that the pellicle membrane itself is susceptible to damage during manufacturing. Small defects or damaged areas in a very thin membrane can be detrimental to the physical properties of the membrane.

[0015] Since any defect within the pellicle can reduce the performance and / or lifespan of the pellicle, it is desirable to reduce the likelihood of membrane assemblies, such as the pellicle, being deformed or damaged during manufacturing. Additionally, since the process of manufacturing the pellicle is time-consuming and expensive, it is desirable to increase the yield of undamaged pellicles during manufacturing.

[0016] Etching is a common manufacturing process used to remove portions of material. In multilayer materials, selective etching can remove a portion of the outer layer to expose the underlying layer. A well-defined layer thickness is beneficial because etching typically occurs at a fixed rate over time, and therefore, thicker layers take longer to etch than thinner layers. Similarly, it can be understood that non-uniform layer thickness will provide variations in etching time depending on the thickness at each part of the layer. Over-etching can occur when more material is removed than desired. Over-etching can occur on films with non-uniform layer thickness because thinner parts of the layer may be etched before thicker parts complete the etching process. This can result in damage to the underlying or upper layer caused by over-etching, depending on which side of the stack is being etched. In pellicle manufacturing, over-etching can cause damage to the pellicle film. Therefore, it is desirable to reduce the possibility of over-etching. In addition, to achieve pellicle membranes and pellicle assemblies with reliable and consistent characteristics, it is desirable to develop a manufacturing process that facilitates the deposition of a layer with a well-defined layer thickness or removes a portion of the material in a controlled manner.

[0017] The present invention was devised as an attempt to solve at least some of the aforementioned problems.

[0018] According to a first aspect of the present invention, a method for manufacturing a pellicle membrane and / or a pellicle assembly for EUV lithography is provided, wherein a layer forming at least a portion of the pellicle membrane is provided after one or more etching steps that define a pellicle boundary that retains the pellicle membrane.

[0019] The fabrication of pellicles involves multiple steps of material deposition and removal using methods such as (but not limited to) chemical vapor deposition, etching masking, and etching. During these processes, the stack can be handled and manipulated to bring it into a desired orientation. In some steps, the stack can be inverted, and in others, the stack can be held in place using a fixing mechanism such as a chuck. These chucks can apply force to the layers within the stack during fabrication, which may cause damage. The chucks may also scratch or otherwise damage one or more layers within the stack.

[0020] In other methods for manufacturing pellicle membranes and membrane assemblies for EUV lithography, the layer or layers that ultimately form the pellicle membrane are deposited in an initial stage. This ensures that the pellicle membrane layer is deposited or otherwise provided on a clean surface that is substantially free of contaminants or defects. After the deposition of the layer or layers to finally form the pellicle membrane, additional deposition, protection, and etching steps are performed to form the final pellicle membrane or pellicle assembly. However, during additional processing steps, the layer or layers to form the final pellicle membrane may be damaged. In other manufacturing methods, the final pellicle membrane layer is covered by other layers until later stages of the process. Thus, if any defects or damage exist in the final pellicle membrane, they are not revealed until a number of complex and time-consuming steps are completed. Therefore, almost the entire manufacturing process must be carried out before a defective pellicle membrane can be identified and discarded. The time taken between the identification of the defect and the creation of a new pellicle assembly can be referred to as the learning time. The method according to the present invention has the advantage that the learning time is reduced.

[0021] In the method according to the first aspect of the present invention, the layer or layers that ultimately form the pellicle membrane are provided at a later stage of the process than in other methods. In the present invention, the final pellicle membrane layer is deposited only after specific etching steps occur. The final pellicle assembly includes a pellicle boundary that holds the pellicle membrane. The pellicle boundary may be mechanically or chemically attached to a pellicle frame. The pellicle frame may be detachably or permanently attached to a patterning device (MA). By pellicle membrane, it is understood to refer to a layer or layers of material that spans the pellicle boundary portion and through which EUV radiation passes when used as a pellicle. The layer may also be referred to as a pellicle layer, a pellicle core layer, or a pellicle membrane. The material forming the pellicle membrane is provided after the etching step or steps defining the pellicle boundary occur. It should be recognized that this does not require the formation of a pellicle boundary, but rather that a layer or layers are defined to protect a portion of a layer, such as a planar substrate, which ultimately becomes the pellicle boundary in subsequent etching steps. For example, if the stack includes a silicon planar substrate that forms a final pellicle boundary holding a pellicle membrane, the etching step for forming the final pellicle boundary may include a step of etching one or more layers that serve to protect from etching a portion of the planar substrate where the final pellicle boundary is formed.

[0022] Surprisingly, it has been recognized that it is possible to provide a layer or membrane that ultimately forms at least a portion of the final pellicle membrane after some etching steps are performed, without being detrimental to the quality of the final pellicle membrane. Furthermore, the method of the present invention can also reduce the time required to manufacture pellicle assemblies in that it is possible to perform some of the steps required to manufacture a pellicle assembly or a pellicle membrane starting from a stack before the layer or membrane that becomes the final pellicle membrane is provided. In other manufacturing methods where the pellicle membrane layer needs to be deposited early, if a membrane assembly having a specific pellicle membrane is required, it is necessary to start from the initiation of the process for forming the pellicle membrane. In contrast, the method of the present invention can efficiently start the entire process from the portion forming the pellicle membrane layer, thereby reducing time.

[0023] The present method may include the step of providing a stack having a front surface and a rear surface. The stack may include a substrate having one or more layers. For example, the stack may include a planar substrate such as a silicon wafer or a silicon on insulator (SOI) wafer.

[0024] The method may also include the step of providing a protective layer on the front surface of the stack. The protective layer may be any suitable material capable of protecting the lower portion of the stack from a subsequent etching process. The invention is not particularly limited by the properties of the protective layer.

[0025] The present method may also include the step of selectively removing one or more portions from the back surface of the stack. These portions may serve to define the pellicle boundaries of the final pellicle assembly. Selective removal may be performed by any suitable technique, and the present invention is not particularly limited by the technique used. During manufacturing processes such as resist deposition, patterning, and etching, the stack must be held in place or moved using a fixing mechanism also known as a chuck. In alternative manufacturing methods, these chucks may apply force to the pellicle layers during manufacturing, which may further cause damage to the pellicle. An advantage of the present invention is that the selective removal of at least a portion of the back surface of the stack is completed prior to the deposition of at least one membrane layer, ensuring that the chucks do not apply force to the membrane layer at this point. This reduces the likelihood of damage to the pellicle membrane or layer during processing.

[0026] The present method may also include the step of removing at least a portion of the protective layer from the front of the stack. When the back of the stack is etched, the protective layer on the front of the stack can be removed because it no longer requires protection from etching. The removal of the protective layer can be achieved by any suitable technique, and the present invention is not particularly limited to the technique used.

[0027] The present method may also include the step of providing a layer forming at least a portion of a pellicle membrane on the front surface of a stack. It is preferable to provide a protective layer on the front surface of the stack to protect the front surface of the stack during the etching step, but this may not be required, and it may be possible to etch the back surface of the stack without providing any protective layer on the front surface of the stack. Since the etching of the back surface of the stack is completed before the layer forming at least a portion of the pellicle membrane is provided, this reduces the risk of damage to the pellicle layer. The present invention is not particularly limited to the method of providing the pellicle layer, and any suitable technique, such as chemical vapor deposition, may be used.

[0028] The present method may further include the step of selectively removing one or more portions of a stack to form a pellicle assembly. Accordingly, the pellicle assembly may include a pellicle membrane comprising at least one membrane layer and a pellicle boundary retaining the pellicle membrane. One or more portions from the stack may be removed by any suitable technique, and the present invention is not particularly limited by the technique or techniques used. For example, etching may be used to remove one or more portions. The present method may include one or more steps of selectively removing one or more portions of a stack to form a pellicle assembly.

[0029] The present method may further include the step of providing at least one radiating layer on the front surface of a stack such that the pellicle assembly comprises a membrane including at least one membrane layer and at least one radiating layer. The radiating layer is preferably provided after one or more membrane layers are provided. The radiating layer may be provided below at least one membrane layer, or above and below at least one membrane layer. As such, the radiating layer may be provided on the front surface, back surface, or both sides of the pellicle membrane. The radiating layer may serve to increase the thermal emissivity of the pellicle assembly. An increase in the emissivity of the pellicle assembly can reduce the operating temperature of the pellicle, which can ultimately increase the lifespan of the pellicle. Additionally, the radiating layer may protect the membrane layer from the atmosphere within the lithography device. For example, if the pellicle layer contains carbon, low-pressure hydrogen within the lithography device may be ionized by radiation, and hydrogen radicals may attack the carbon, weakening the pellicle over time. Accordingly, the radiation layer can also protect the pellicle membrane layer. If the radiation layer is provided on the rear side of at least one membrane layer, it may also be provided on the inner face of the boundary. Alternatively or additionally, the radiation layer may also be provided on the lowest part of the boundary, i.e., on the "feet" of the boundary. While it may be possible to provide only the radiation layer on the membrane layer, it may be more convenient to simply coat the lowest face of the assembly with the radiation layer.

[0030] The present method may further include the step of providing at least one capping layer on the front surface of the stack, wherein the capping layer preferably comprises silicon dioxide and / or silicon nitride. Other capping layers may also be used. The capping layer may be provided by any suitable technique, and the present invention is not particularly limited to the technique used. In one example, tetraethyl orthosilicate (TEOS) may be provided and subsequently converted to silicon dioxide using known techniques. The capping layer may serve to protect the pellicle core layer of the stack. The capping layer may have better compatibility with the layers placed over it, thereby resulting in stronger bonding between the layers within the stack. Thin layers of silicon dioxide are easily grown to widely known layer thicknesses as known in the art. Layers of well-known thicknesses are advantageous for etching processes because they reduce the risk of over-etching in some regions of the layer due to non-uniform layer thickness. Depositing a thin layer of silicon dioxide as a capping layer can subsequently increase the reliability of etching and reduce the possibility of damage to the membrane.

[0031] The present method may include the step of providing a resist on a stack and the step of patterning the resist prior to the step of selectively removing one or more portions from the back surface of the stack. The present invention is not particularly limited by the properties of the resist, and any suitable resist may be used. This step is to provide a mask that allows the definition of a pattern on the surface of the stack, for example, to define a pellicle boundary region on the stack. The resist may be patterned in a manner that defines the final pellicle boundary of the final pellicle assembly. The resist serves to protect the underlying layers from etching. As such, the patterning of the resist serves to define regions of the stack that are removed by a subsequent etching step. The etchant may be a chemical etchant, such as phosphoric acid (H3PO4) and / or hydrofluoric acid (HF). After etching, the resulting pellicle membrane may comprise a MoSiNx pellicle core layer having native oxide layers on one or both of its surfaces, for example. Here, x represents the variability of nitrogen in the material composition, and this variability can also be described as MotSipNz. Alternatively, after etching and metal deposition, the stack can be formed, for example, by a SiN / Ox / pSi pellicle core layer / low stress nitride (LSN) on the front surface and a Mo / Ru cap (for example, a cavity defined by the pellicle boundary) on the back surface of the stack.

[0032] The present method may further include the step of selectively removing one or more portions from the back of the stack and / or the step of etching at least a portion of the stack during the step of selectively removing one or more portions of the stack to form a pellicle assembly.

[0033] The stack may comprise a planar substrate and, preferably, at least one sacrificial layer. The planar substrate may be a wafer. The planar substrate may form a pellicle core layer of the stack. Preferably, the wafer comprises silicon. Silicon is a well-characterized material commonly used in the art. It will be understood that other suitable materials may be used, and that the present invention is not limited to silicon-based substrates (i.e., substrates containing silicon such as pSi, SiC, MoSi2, or MoSiNx). For example, the substrate may also be carbon-based, such as a graphene pellicle core layer or a carbon nanotube pellicle core layer for the stack.

[0034] The method may further include the deposition of one or more additional sacrificial layers, for example, during the deposition of at least one membrane layer. This is preferably followed by the selective removal of one or more portions of the additional sacrificial layers. The sacrificial layers may comprise silicon nitride and / or silicon oxide. Depending on the material of the pellicle core layer, other materials may also be used as sacrificial layers.

[0035] At least one membrane layer may preferably comprise at least one silicon layer formed by crystallizing at least one amorphous silicon layer. The membrane layer may comprise pSi. Silicon is a suitable material for at least one membrane layer because it has good EUV transmittance. At least one membrane layer may be coated with one or more materials that serve to provide additional chemical or thermal resistance and / or increase the emissivity of the membrane assembly.

[0036] The protective layer may comprise a cross-linked polymer. The polymer may be a poly(p-xylylene) polymer. The polymer may be Parylene or a ProTek® type material. Alternatively or additionally, for example, KMPR TMIt may include a register such as.

[0037] At least one membrane layer may be disposed between at least one radiating layer and the front of the stack. In some embodiments, it will be understood that the radiating layer may be provided on one or both sides of the membrane layer. In one embodiment, the membrane layer is formed solely by at least one pellicle core layer without having a radiating layer or other capping layers. For example, the pellicle is formed solely by a MoSiNx pellicle core layer.

[0038] At least one radiating layer may be metallic. At least one radiating layer may comprise boron or a boron-containing material, or Zr or a Zr-containing material. Boron-containing materials, such as metal alloys of boron like zirconium diboride (ZrB2), can increase the emissivity of the pellicle and also protect the membrane layer.

[0039] Preferably, one or more emitting layers may further comprise three metal emitting layers. In this embodiment, the three emitting layers may comprise a zirconium layer disposed between two boron layers, wherein the zirconium layer may comprise zirconium or a zirconium-containing material, and the boron layer may comprise boron or a boron-containing material. In another alternative, the emitting layers may comprise a layer of B, Zr, Ru, or Mo. Other emitting layers may be used.

[0040] At least one capping layer has a capping layer thickness, and at least one membrane layer has a membrane layer thickness, wherein the capping layer thickness is preferably smaller than the membrane layer thickness. For example, the capping layer may have a thickness of 0.5 to 10 nm, preferably 1 to 5 nm. In this way, the membrane layer provides most of the physical strength of the pellicle membrane within the pellicle assembly.

[0041] The method may further include the step of selectively removing at least one portion of at least one capping layer after selectively removing one or more portions of a stack to form a pellicle assembly.

[0042] One or more sacrificial layers may be additionally provided on one or more membrane layers and / or one or more capping layers and / or one or more radiating layers. The method may further include providing additional sacrificial layers, for example, before, during, or after the deposition of at least one membrane layer. This is preferably followed by the selective removal of one or more portions of the additional sacrificial layers.

[0043] According to a second aspect of the present invention, a pellicle substrate comprising a stack having a front surface and a back surface is provided, and one or more layers on the back surface of the stack are optionally removed to define a pellicle boundary region for holding the pellicle membrane before a layer forming at least a portion of the pellicle membrane is provided.

[0044] According to the present invention, a partially processed pellicle substrate can be provided. Since the processing of a pellicle substrate may take several weeks, providing a partially processed pellicle substrate allows such substrates to be maintained in storage until they are required, thereby reducing the time required between sequences of membrane assemblies having a specific pellicle membrane. During manufacturing, defects in the pellicle layer may be identified, in which case the pellicle must be discarded and a new pellicle assembly must be manufactured. According to the above-described aspect of the present invention, the manufacturing process can be continued from the preparation stage of the pellicle substrate rather than the initial start stage, thus shortening the learning time of the manufacturing process.

[0045] In one embodiment, the pellicle substrate may not have a layer forming at least a portion of the pellicle membrane. In this embodiment, the pellicle substrate is processed so that the final pellicle boundary region is defined, but no material forming the pellicle membrane is present. In this way, different pellicle membrane materials may be provided and may be investigated or used more quickly than before.

[0046] In another embodiment, the pellicle substrate comprises a material that forms the final pellicle membrane. However, this is provided after processing steps defining the final pellicle boundary region are performed.

[0047] Preferably, the pellicle substrate comprises at least one protective layer on its front surface, and preferably, the at least one protective layer is a cross-linked polymer, preferably a poly(p-xylylene) polymer, preferably Parylene or a ProTEK® type material or a resist, such as KMPR TM Includes

[0048] The stack may include a planar substrate and preferably at least one sacrificial layer; preferably, the planar substrate is a wafer, optionally a silicon wafer or an SOI wafer; and preferably, at least one sacrificial layer comprises silicon nitride.

[0049] According to another aspect of the present invention, a pellicle assembly manufactured according to a method comprising any of the aforementioned methods is provided.

[0050] In one embodiment, the method according to the present invention results in, after etching, that the pellicle membrane comprises a MoSiNx core layer having no additional functional cap layers, or a MoSiNix core layer having at least one surface covered with a native oxide layer.

[0051] In one embodiment, the method according to the present invention results in a pellicle stack being formed after etching and metal deposition by a SiN / Ox, pSi pellicle core layer on the front side, a low stress nitride (LSN) layer, and a cap layer of Ru on Mo deposited on the back side of the stack.

[0052] In another aspect of the present invention, the pellicle substrate comprises a pellicle core layer that can be selected from silicon-based materials such as pSi, SiC, MoSi2 or MoSiNx, or carbon-based materials such as a graphene film or a film formed by carbon nanotubes.

[0053] In another aspect of the present invention, the pellicle stack comprises layers of SiO / MoSiNx / MOSi2 or layers of SiON / MoSiONx / SiON. However, a combination of only two of these layers is also conceived herein.

[0054] It will be understood that the final pellicle provided by the present invention is fundamentally identical to pellicle assemblies manufactured using other methods, but the provision of a pellicle layer in a subsequent stage of the process has a number of advantages as described above that have not been previously realized.

[0055] It will be understood that any of the embodiments of the present invention discussed above may be combined with one or more other embodiments of the present invention where appropriate. Additionally, an optional feature described in connection with one of the embodiments of the present invention may, where appropriate, be an optional feature of one of the other embodiments of the present invention. Brief explanation of the drawing

[0056] Embodiments of the present invention will now be described merely by way of example with reference to the accompanying schematic drawings. FIG. 1 illustrates a lithography system including a lithography device including a pellicle assembly. Figure 2 illustrates a pellicle assembly. FIG. 3 illustrates the steps of manufacturing a pellicle assembly according to a method other than the method according to the present invention, using a cross-section of a stack for example. FIG. 4 illustrates the manufacturing steps of a pellicle assembly according to one embodiment of the present invention, using a cross-section of a stack for example. FIG. 5 illustrates an embodiment of the present invention after the deposition of a plurality of membrane layers. FIG. 6 illustrates an embodiment of the present invention and shows the final pellicle assembly before and after final etching. FIG. 7 illustrates another embodiment of the present invention after deposition of a plurality of membrane layers. FIG. 8 illustrates another embodiment of the present invention showing the final pellicle assembly before and after final etching. FIG. 9 illustrates an example of a pellicle assembly in which a light-emitting layer is provided on the back surface of the assembly. The features and advantages of the present invention will become more apparent from the detailed description below when the same reference numerals are taken together with drawings identifying corresponding elements throughout. In the drawings, similar reference numerals generally indicate identical, functionally similar, and / or structurally similar elements. Specific details for implementing the invention

[0057] FIG. 1 illustrates a lithography system comprising a pellicle (15) (also referred to as a pellicle assembly) manufactured according to the method of a first aspect of the present invention. The lithography system comprises a radiation source (SO) and a lithography device (LA). The radiation source (SO) is configured to generate an extreme ultraviolet (EUV) radiation beam (B) and supply the EUV radiation beam to the lithography device (LA). The lithography device (LA) comprises an illumination system (IL), a support structure (MT) configured to support a patterning device (MA) (e.g., a mask), a projection system (PS), and a substrate table (WT) configured to support a substrate (W).

[0058] The illumination system (IL) is configured to regulate the radiation beam (B) before the radiation beam (B) is incident on the patterning device (MA). The substrate (W) may contain previously formed patterns. In this case, the lithography device aligns the patterned radiation beam (B) with the previously formed patterns on the substrate (W). It will be understood that the pellicle assembly (15) can be positioned at any required location and can be used to protect any mirror within the lithography device.

[0059] The radiation source (SO), the illumination system (IL), and the projection system (PS) can all be configured and arranged to be isolated from the external environment. A gas (e.g., hydrogen) at a pressure below atmospheric pressure may be supplied to the radiation source (SO). A vacuum may be supplied to the illumination system (IL) and / or the projection system (PS). A small amount of gas (e.g., hydrogen) at a pressure much lower than atmospheric pressure may be supplied to the illumination system (IL) and / or the projection system (PS).

[0060] The radiation source (SO) may take any form and may be a type that can be referred to, for example, as a laser-generated plasma (LPP) source. In an alternative example, the radiation source (SO) may include one or more free electron lasers. One or more free electron lasers may be configured to emit EUV radiation that can be supplied to one or more lithography devices.

[0061] A radiation beam (B) passes from a radiation source (SO) to an illumination system (IL), and the illumination system 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 the radiation beam (B) with a desired cross-sectional shape and a desired angular distribution. The radiation beam (B) passes from the illumination system (IL) and is incident on a patterning device (MA) held by a support structure (MT). The patterning device (MA) is protected by a pellicle layer (19) held in place by a pellicle boundary (17). The pellicle layer (19) and the pellicle boundary (17) together form a pellicle assembly (15). The patterning device (MA) (which may be, for example, a mask) reflects and patterns the radiation beam (B). The lighting 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).

[0062] Following reflection from the patterning device (MA), the patterned radiation beam (B) enters the projection system (PS). The projection system includes 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) can apply a reduction factor to the radiation beam to form an image having features smaller than the corresponding features on the patterning device (MA). For example, a reduction factor of 4 may be applied. Although the projection system (PS) has two mirrors (13, 14) in FIG. 1, the projection system may include any number of mirrors (e.g., six mirrors).

[0063] The radiation sources (SO) illustrated in FIG. 1 may include components not illustrated. For example, a spectral filter may be provided to the radiation source. The spectral filter may be substantially penetrating to EUV radiation but may substantially block other wavelengths of radiation, such as infrared radiation.

[0064] As briefly described above, the pellicle assembly (15) includes a pellicle layer (19) provided adjacent to the patterning device (MA). The pellicle layer (19) is provided in the path of the radiation beam (B) so that the radiation beam (B) passes through the pellicle layer (19) as the radiation beam (B) approaches the patterning device (MA) from the illumination system (IL) and as the radiation beam is reflected by the patterning device (MA) toward the projection system (PS). The pellicle layer (19) includes a thin film that is substantially transparent to EUV radiation (although it will absorb a small amount of EUV radiation). The pellicle layer (19) serves to protect the patterning device (MA) from particle contamination. The pellicle layer (19) may be referred to herein as an EUV transparent pellicle.

[0065] Although efforts may be made to maintain a clean environment inside the lithography device (LA), particles may still be present inside the lithography device. Without the pellicle layer (19), particles may be deposited on the patterning device (MA). Particles on the patterning device (MA) may adversely affect the pattern applied to the radiation beam (B) and thus the pattern transferred to the substrate (W).

[0066] When in use, the pellicle layer (19) is positioned at a predetermined distance from the patterning device (MA), which is sufficient so that any particles incident on the surface of the pellicle layer are not in the focal plane of the radiation beam (B). This separation between the pellicle layer (19) and the patterning device (MA) serves to reduce the extent to which any particles on the surface of the pellicle layer impart a pattern to the radiation beam (B). In some embodiments, the gap between the pellicle layer (19) and the patterning device (MA) may be, for example, 2 mm to 3 mm (for example, about 2.5 mm). In some embodiments, the gap between the pellicle layer (19) and the patterning device may be adjustable.

[0067] In one embodiment, the pellicle assembly (15) is for a dynamic gas lock. In this case, the membrane assembly (15) functions as a filter for filtering DUV radiation. Additionally or alternatively, in one embodiment, the membrane assembly (15) is a pellicle for a patterning device (MA) for EUV lithography. The membrane assembly (15) of the present invention may be used for a dynamic gas lock or a pellicle, or for other purposes. In one embodiment, the membrane assembly (15) comprises a membrane formed from at least one membrane layer configured to transmit at least 90% of incident EUV radiation. To ensure maximized EUV transmission and minimized impact on imaging performance, it is preferable that the membrane be supported only at the boundaries.

[0068] FIG. 2 is a cross-sectional and more detailed schematic diagram of a pellicle assembly (15) and a patterning device (MA). The patterning device (MA) has a patterned surface (24). A pellicle boundary (17) supports the pellicle layer (19) centered on the periphery of the pellicle layer (19). The pellicle boundary (17) may be attached to a pellicle frame (22). The pellicle frame (22) may include an attachment mechanism (not shown) configured to allow the pellicle frame (22) to be detachably attached to the patterning device (MA) (i.e., to allow the pellicle frame (22) to be attached to and detached from the patterning device (MA). The attachment mechanism is configured to engage with an attachment feature (not shown) provided on the patterning device (MA). The attachment feature may be, for example, a protrusion extending from the patterning device (MA). The attachment mechanism may include, for example, a locking member that engages with a protrusion and secures the pellicle frame (22) to the patterning device (MA). A plurality of attachment mechanisms and associated attachment features may be provided. The attachment mechanisms may be distributed around the pellicle frame (22) (for example, two on one aspect of the pellicle frame and two on opposite aspects of the pellicle frame). The associated attachment features may be distributed around the perimeter of the patterning device (MA).

[0069] A contaminant particle (26) is schematically illustrated in FIG. 2. The contaminant particle (26) is incident on the pellicle layer (19) and is retained on the pellicle layer (19). The pellicle layer (19) retains the contaminant particle sufficiently far from the patterned surface (24) of the mask (MA) so that the contaminant particle is not imaged onto the substrate by the lithography device (LA).

[0070] A pellicle assembly according to one embodiment of the present invention may allow a mask pattern (on a patterning device) to be provided that remains substantially defect-free during use (the mask pattern is protected from contamination by the pellicle).

[0071] The pellicle assembly (15) may be constructed by directly depositing a pellicle layer (19) (e.g., a pellicle core layer made of polysilicon (pSi) or MoSiNx) on the upper (front) side of a substrate to provide a pellicle boundary (17). For example, the stack may be SiO / MoSiNx / MoSi2 or SiON / MoSiNx / SiON. The substrate may be, for example, a silicon wafer or an SOI wafer. After depositing the film of the pellicle layer (19), the substrate may be optionally back-etched (i.e., etched from the back) to remove the central portion of the substrate and leave only the outer perimeter to form the pellicle boundary (17) to support the pellicle layer (19). The manufacturing process will be discussed with reference to the following drawings.

[0072] FIG. 3 schematically illustrates the steps of manufacturing a pellicle assembly according to an alternative manufacturing process different from the method of the present invention, using a cross-section of a stack for example. This method is included to provide a comparison with the method of the present invention.

[0073] A stack (100) comprising a flat substrate (30) and a first optional sacrificial layer (31) is provided. The flat substrate (30) is disposed in an internal region of the stack (100), and the first sacrificial layer (31) is disposed in an external region of the stack. Thus, the first sacrificial layer (31) preferably substantially surrounds the flat substrate (30). The flat substrate (30) may be, for example, a silicon wafer or an SOI wafer. The flat substrate (30) has a shape such as, for example, a square, a circle, a rectangle, etc. The shape of the flat substrate (30) is not particularly limited, but it is likely to be circular because it is the most commonly available shape. The size of the flat substrate (30) is not particularly limited.

[0074] The first sacrificial layer (31) is illustrated as completely surrounding the planar substrate (30), but in some embodiments, the first sacrificial layer (31) may only partially surround the planar substrate (30). In the illustrated embodiment, a single sacrificial layer (31) is illustrated, but it will be understood that there may be more sacrificial layers than are present. The first sacrificial layer may comprise, for example, silicon oxide, silicon nitride, tetraethyl orthosilicate (TEOS), chemical oxide, or thermal oxide.

[0075] The stack (100) has a front side and a back side (also referred to as the back side). The front side is defined as the side adjacent to the pellicle layer in a subsequent manufacturing step. The front and back sides may be designated prior to the deposition of the pellicle layer. These terms are used to provide a better understanding of the invention and to define the steps of the process more clearly. However, the method is also intended to cover cases where the stack is inverted or otherwise rotated.

[0076] At least one pellicle layer (32) is placed on the first sacrificial layer (31) to define the stack (101). Again, although the pellicle layer (32) is shown as surrounding the first sacrificial layer (31), in alternative embodiments, the membrane layer (34) may only partially surround the first sacrificial layer (32) or be deposited on one side of the stack (100). The pellicle layer (32) may also be known as a pellicle film, a membrane layer, a pellicle core layer, or a membrane film.

[0077] Although a single pellicle layer (32) is illustrated, it will be understood that the pellicle layer (32) may comprise a plurality of layers. The pellicle layer will comprise at least one pellicle core layer. The pellicle core layer may comprise, for example, polysilicon (pSi) or MoSiNx. The pellicle core layer has two main purposes: to provide mechanical strength to the pellicle layer (32) and to allow the penetration of radiation, for example, EUV. The pellicle layer (32) may also comprise at least one additional sacrificial layer (not illustrated).

[0078] The stack (101) may also include several different layers of materials deposited on a planar substrate (30), and the layers have various protective functions in the manufacturing process of the pellicle assembly (15) or to improve the properties of the pellicle assembly (15), such as resistance to chemicals / environments and / or improved (thermo-)mechanical strength and / or reduced imaging effects (e.g., by reducing pellicle reflections of EUV radiation or improving reflections of unwanted out-of-band radiation such as DUV or IR radiation).

[0079] The stack (102) illustrates a step in which a first resist (33) is deposited. The first resist (33) may be a positive or negative type resist, and the method of using the resist is not particularly limited. The first resist (33) is patterned to define portions of the stack (103) to be etched in a subsequent etching step. The first resist (33) may also be known as an etching mask.

[0080] Afterward, the stack (102) can be etched by any suitable etching means to remove a portion of the pellicle layer (32) not protected by the resist (33) to create the stack (103). This etching step can also remove portions of the sacrificial layer (31), or any additional layers described above if designed so.

[0081] Subsequently, a protective layer (34) is applied to the front side of the stack (14) to protect the surface at the front of the stack (104). In particular, the protective layer can protect the layers, particularly the pellicle layer (32), at the front of the stack (104) from subsequent etching steps and / or physical contact. The protective layer (34) may comprise a cross-linked poly(p-xylylene) polymer, for example, preferably Parylene or ProTEK® type material, or a resist, for example, a KMPR® and / or TEOS layer. The protective layer (34) is applied as a substantially pore-free continuous layer to provide a layer impermeable to the etchant. The protective layer (34) is preferably not applied to the back side (i.e., rear) of the stack so that the etchant can access the planar substrate (30) and any sacrificial layers (31) through the back side of the stack (104). An optional protective layer (34) is applied to the front of the stack to protect the surface on the front of the stack. This enables the maintenance of a clean deposition surface during subsequent processing steps prior to the deposition of the pellicle layers (32). It will be understood that the protective layer (34) may be absent if etching of the rear of the stack does not pose a risk of damaging the front of the stack. Even so, the protective layer (34) is preferred.

[0082] Next, the stack (104) is inverted, and a second resist (35) is deposited on the back surface of the stack (105). The second resist (35) may be a positive or negative type resist, and the method of using the resist is not particularly limited. The second resist (35) is patterned to define portions of the stack (105) to be etched in a subsequent etching step. The second resist (35) may also be known as an etching mask. At this step, the final pellicle boundary region is defined in this process, after the pellicle layer has been provided.

[0083] At this point in the manufacturing process, contact may occur between the stack (105) and the chuck (not shown). The chuck may include, for example, edge contacts, lift pins, end effectors, and center wheel contacts used to hold, move, and align the stack. These contacts may occur on the front surface of the stack (105) in the presence of the pellicle layer (32), which poses a high risk of damaging the pellicle layer (32).

[0084] The present invention has the advantage of mitigating such damage risk by providing a different manufacturing process, which will be further explained below with reference to FIG. 4.

[0085] FIG. 4 schematically illustrates the manufacturing steps of a pellicle assembly according to one embodiment of the present invention. A cross-section of a stack is used for illustrative purposes. The manufacturing steps will be discussed below. Some of the stages and materials are similar to those described above and will not be described in detail, but may be considered equivalent.

[0086] A stack (200) comprising a planar substrate (30) and a first sacrificial layer (31) is provided. To protect the surface on the front side of the stack (201), an optional protective layer (34) is applied to the front side of the stack (200). This enables the maintenance of a clean deposition surface during subsequent processing steps prior to the deposition of the pellicle layers (32). It will be understood that the protective layer (34) may be absent if etching of the rear side of the stack does not pose a risk of damaging the front side of the stack. Nevertheless, the protective layer (34) is preferred.

[0087] The stack (201) is inverted, and the first resist (35) is applied to the back (i.e., rear) side of the stack (220). The inversion of the stack (201) is optional, and it may be possible to perform the process without inversion. The resist (35) is patterned to define portions of the stack (202) to be etched in a subsequent etching step, which serves to define the pellicle boundaries of the final pellicle assembly. Subsequently, the stack (202) may be etched by any suitable etching means to remove portions of the first sacrificial layer (31) that are not protected by the resist (35). At this point, the pellicle boundaries of the ultimate pellicle assembly have been defined, and this is before the material providing the ultimate pellicle membrane is provided. At this point in the manufacturing process, contact may occur between the stack (202) and the chuck. These contacts may occur on the front surface of the stack (202) where the pellicle layers (32) are not present. In this way, the present invention mitigates the high risk of damage to the pellicle layer (32).

[0088] Next, the resulting stack (203) can be used for the subsequent deposition of pellicle layers and the subsequent manufacture of a pellicle assembly. The resulting stack (203) may also be known as a pellicle substrate (202). The pellicle substrate (203) can be maintained without deterioration or contamination of the front surface of the stack (202) for a considerable period prior to additional manufacturing steps. In this way, if the pellicle layers are damaged during additional manufacturing steps, manufacturing can be resumed from the stack (203) (rather than from the stack (100) in an alternative manufacturing process), thereby reducing the learning time of the process.

[0089] After the removal of the protective layer (34), at least one pellicle layer (32) is provided on the stack (203) to define a new stack (204). Again, although the pellicle layer (32) is shown to surround the entire stack (203), in alternative embodiments, the membrane layer (322) may only partially surround the stack (303) or may be deposited on one side of the stack (303). The pellicle layer may also be known as a pellicle film, a membrane layer, or a membrane film.

[0090] Although a single pellicle layer (32) is shown, it will be understood that there may be more than the pellicle layer (32). The pellicle layer may include at least one pellicle core layer. The pellicle core layer may include, for example, polysilicon (pSi) or MoSiNx. The pellicle core layer has two main purposes: to provide mechanical strength to the pellicle layer (32) and to allow the penetration of radiation, for example, EUV.

[0091] In alternative embodiments, the pellicle layer (32) may also include at least one additional layer, and the layers have various protective functions to increase the properties of the pellicle assembly, such as resistance to chemicals / environments and / or improved (thermo-)mechanical strength and / or reduced imaging shock and / or emissivity (e.g., by reducing pellicle reflections), in the manufacturing process of the pellicle assembly (15). For example, there may be cases where at least one additional layer, such as a boron or boron-containing layer, is already provided before the pellicle layer is provided. Some additional embodiments will be described in more detail below and in FIGS. 5-8.

[0092] After the deposition of at least one pellicle layer (32), the stack (204) may be further processed to remove portions of material to form a final pellicle assembly (15). The selective removal of portions of material causes the pellicle assembly (15) to be removed from the peripheral portions of the planar substrate (30) and the sacrificial layers (31). The removal area is defined using a resist (35). The selective removal of portions of material further defines the pellicle layer (19) and the pellicle boundary (17). Additional processing steps are not particularly related to the present invention and are therefore not described in detail herein. Conventional processing steps include, but are not limited to, the application of additional resist and / or masking layers, etching steps, and the addition and removal of a protective layer.

[0093] An additional processing step may occur after removing the membrane assembly (15) from the peripheral portion of the planar substrate (30) and the sacrificial layer (31). For example, the pellicle layer (32) of the pellicle assembly (15) may include an additional sacrificial layer or capping layer as described above. These additional layers may be removed or processed in an additional processing step.

[0094] FIGS. 5 and 6 illustrate a preferred embodiment of the present invention in which the composition of the pellicle layer (32) is further defined. A feature of the present invention is that later deposition of the pellicle layer (32) in the manufacturing process allows for a wider range of materials and layer thicknesses can be used. This reduces the risk of damage to the pellicle layer, partly due to the deposition of the pellicle layer (32) after the selective removal of one or more portions from the back of the stack.

[0095] In this embodiment, the pellicle layer (32) is deposited as most clearly illustrated in FIG. 5. In this embodiment, the pellicle layer comprises a pellicle core layer (51), two capping films (52), and a spacing film (53). The pellicle core layer (51) is placed between the two capping films (52) to form a capped pellicle layer (55). The pellicle core layer may also be referred to as a pellicle film or a core film. The spacing film (53) is placed between the capped pellicle layer (55) and the sacrificial layer (31). Preferably, an optional additional spacing layer (56) is provided between the spacing film (53) and the first capping layer (52). This additional optional spacing layer (56) may act as an etch-stop in a future etching step.

[0096] The pellicle core layer (51) may include polysilicon (pSi) which not only has high transmittance in EUV, for example, but also provides strength to the pellicle assembly.

[0097] The spacing film (53) may be made from, for example, silicon oxide, preferably thermal oxide. The spacing film (53) forms a surface for receiving additional pellicle layers (51, 52). The additional spacing layer (56) may comprise any material having etching selectivity compared to silicon oxide, for example, silicon, or silicon nitride.

[0098] The capping layer (52) may preferably be composed of silicon oxide, for example, silicon dioxide (SiO2). The capping layer (52) is preferably a thin film compared to the thickness of the pellicle core layer. A thin film of SiO2 can be easily manufactured with a well-defined layer thickness. Since uneven layer thickness can lead to over-etching and consequent damage to the pellicle core layer (51), a well-defined layer thickness is beneficial for pellicle manufacturing. Therefore, it is desirable to provide a layer with a well-defined layer thickness.

[0099] As best illustrated in FIG. 6a, after the removal of the pellicle assembly (15) from the peripheral portions of the material, the pellicle layer comprises a plurality of layers. In this preferred embodiment, the pellicle core layer (51) is preferably composed of silicon, e.g., polysilicon (pSi), or MoSiNx, and the capping layers (52) are preferably composed of silicon oxide, e.g., silicon dioxide (SiO2).

[0100] Subsequently, it is preferable to remove the capping layer (52) to leave only the pellicle core layer (51), as most clearly illustrated in FIG. 6b. This increases the transmittance of the pellicle assembly (15). The final pellicle assembly comprises a pellicle core layer (51) supported on a pellicle boundary (17). The pellicle boundary (17) comprises a sacrificial layer (31) disposed between a planar substrate (30) and a spacing film (53), said spacing film (53) disposed between the sacrificial layer (31) and an optional additional spacing film (56), and the spacing film (56) adjacent to the capping film (52). The pellicle boundary (17) preferably comprises ordered layers consisting of a silicon layer, a silicon dioxide layer, a thermal oxide layer, an optional silicon layer, and a silicon dioxide layer before contacting the pellicle core layer (51).

[0101] The removal of the capping layer (52) can be performed using a number of methods, but is preferably performed by etching.

[0102] FIGS. 7 and FIGS. 8 illustrate a preferred embodiment of the present invention in which the composition of the pellicle layer (32) is further defined. Many features are similar to those described above and therefore will not be described in further detail.

[0103] In this embodiment, the pellicle layer (32) is provided on the stack as most clearly illustrated in FIG. 7. The pellicle layer (32) is deposited on the first sacrificial layer (31). In this embodiment, the pellicle layer (32) comprises a pellicle core layer (51), a first capping film (52a), at least one second capping film (52b), and a spacing film (53). Preferably, the pellicle layer (32) may further comprise a third capping film (52c) and a fourth capping film (52d), and the second, third, and fourth capping films (52b, 52c, 52d) comprise an upper capping layer (52e), also known as an emissive film. The pellicle core layer (51) is placed between the first capping film (52a) and the emissive film (52e) to form a capped pellicle layer (55). A spacing film (53) is placed between the capped pellicle layer (55) and the sacrificial layer (31). As in the previous embodiment, an additional optional spacing layer (56) may be provided between the spacing film (53) and the first capping film (52a). This additional spacing layer (56) acts as an etch-stop in a future etching step.

[0104] The pellicle core layer (51) is preferably composed of silicon, e.g., polysilicon (pSi), or MoSiNx, which not only has high transmittance in EUV but also provides strength to the pellicle assembly. An additional optional spacing layer (56) may comprise any material having etching selectivity compared to silicon oxide, e.g., silicon, or silicon nitride.

[0105] The first capping layer (52a) is preferably composed of silicon oxide, for example, silicon dioxide (SiO2). The first capping layer (52a) is preferably a thin film compared to the thickness of the pellicle core layer (51).

[0106] At least one second capping film (52b) may preferably be metallic. In a preferred embodiment, the second, third, and fourth capping films (52b, 52c, 52d) may all be metallic. In this preferred embodiment, the second capping film (52b) and the fourth capping films (52d) are preferably composed of boron or a boron-containing material, and the third capping layer (52c) is composed of zirconium or a zirconium-containing material. These upper capping films (52e) may provide strength and / or increased emissivity to the resulting pellicle assembly (15).

[0107] These embodiments are advantageous over the prior art because, previously, radiation layers were deposited on a pellicle membrane after removal from the surrounding portions of the material, also known as deposition on a free-standing pellicle. Significant manufacturing difficulties arise from deposition on a free-standing pellicle. The present invention avoids this problem by allowing the deposition of radiation layers before removal.

[0108] As can be most clearly seen in FIG. 8a, after removing the pellicle assembly (15) from the surrounding portion of the material, the pellicle layer comprises a plurality of layers including a pellicle core layer (51) disposed between a first capping film (52a) and a radiating film (52e). Subsequently, it is preferable to remove the first capping layer (52a) to leave only the pellicle core layer (51) and the radiating film (52e). This increases the emissivity of the pellicle assembly (15) while maintaining mechanical strength.

[0109] The final pellicle assembly (15) of this embodiment is most clearly illustrated in FIG. 8b. The pellicle assembly (15) comprises a pellicle layer (19) supported on a pellicle boundary (17), the pellicle boundary comprising portions of a capping layer (52a), an optional spacing layer (56), a spacing layer (53), a sacrificial layer (31), and a planar substrate (30). The optional spacing layer (56) may be further defined as comprising a sacrificial layer (31) disposed between the planar substrate (30) and a spacing film (53), wherein the spacing film (53) is disposed between the sacrificial layer and the optional spacing film (56), and the spacing film is adjacent to the capping film (52a). The optional spacing layer (56) preferably comprises ordered layers consisting of a silicon layer, a silicon dioxide layer, a thermal oxide layer, an optional silicon layer, and a silicon dioxide layer before contacting the pellicle core layer (51).

[0110] The pellicle layer (19) may be further defined as comprising a pellicle core layer (51) composed of a silicon-based material, preferably pSi or MoSiNx, in contact with the pellicle boundary (17), and a radiating layer (52e) preferably metallic, wherein the pellicle core layer is disposed between the pellicle boundary and the radiating film. Optionally, at least one additional radiating layer (58) may be added to the pellicle layer, for example, as shown in FIG. 9. The at least one additional radiating layer (58) may preferably be metallic. For example, the radiating layer may comprise boron or a boron-containing material, or zirconium or a zirconium-containing material. Such additional radiating layer (58) may provide intensity and / or increased emissivity to the resulting pellicle assembly (15). At least one additional radiation layer (58) may be provided on the sacrificial layer or optional protective layers after the removal of sections of the planar substrate (30) and the sacrificial layer (31), but before the pellicle assembly (15) is completely removed from the surrounding planar substrate (30).

[0111] At least one optional additional radiating layer (58) may be provided on the underside (i.e., back or rear) of the pellicle layer (19), which is defined as the plane of the pellicle layer (19) in contact with the pellicle boundary (17). That is, the additional radiating layer (58) may be provided within the region of the pellicle layer (19) contained within the cavity formed by the pellicle boundary (17). The additional radiating layer may also be provided in the region outside the pellicle boundary (17). As illustrated in the embodiment of FIG. 9, the final pellicle assembly (15) may include a pellicle core layer (51) between the two radiating layers (52e, 58). The final pellicle assembly (15) may further include a radiating layer (58) that at least partially surrounds the pellicle boundary (17).

[0112] While this specification refers to specific uses of a lithography device in IC manufacturing, it should be understood that the lithography device described herein may have other applications, such as the manufacturing of integrated optical systems, guide and detection patterns for magnetic domain memory, flat panel displays, liquid crystal displays (LCDs), thin film magnetic heads, etc. The substrate referred to in this specification may be processed before and after exposure, for example, by a track (typically a tool that applies a resist layer to a substrate and develops the exposed resist), a metrology tool, and / or an inspection tool. Where applicable, the disclosure of this specification may be applied to such substrate processing tools and other substrate processing tools. Additionally, since a substrate may be processed one or more times, for example to create a multilayer IC, the term "substrate" as used in this specification may refer to a substrate containing layers that have already been processed multiple times.

[0113] The drawings are intended to be exemplary and are therefore not drawn to scale. This is particularly important, for example, when considering the thickness of pellicle layers on a planar substrate.

[0114] Although specific embodiments of the present invention have been described above, it will be understood that the present invention may be practiced differently from the description. For example, various layers may be replaced with other layers that perform the same function.

[0115] The foregoing description is intended to be illustrative rather than limiting. Accordingly, it will be apparent to those skilled in the art that modifications to the invention as described may be made without departing from the scope of the claims described below. 1. A method for manufacturing a membrane assembly for EUV lithography, wherein a layer forming at least a portion of a pellicle membrane is provided after one or more etching steps defining a pellicle boundary that retains the pellicle membrane. 2. The method of claim 1, wherein the method comprises the step of providing a stack having a front surface and a back surface. 3. The method of claim 2, wherein the method comprises the step of providing a protective layer on the front surface of the stack. 4. The method of claim 2 or 3, wherein one or more portions are selectively removed from the back surface of the stack. 5. The method of claim 3 or 4, wherein the method comprises the step of removing at least a portion of the protective layer from the front surface of the stack. 6. The method of any one of claims 2 to 5, wherein the method comprises the step of providing a layer forming at least a portion of a pellicle membrane on the front surface of the stack. 7. A method according to any one of claims 2 to 6, comprising the step of selectively removing one or more portions of a stack to form a pellicle assembly, wherein the pellicle assembly comprises a pellicle membrane comprising at least one membrane layer and a pellicle boundary retaining the membrane. 8. A method according to any one of claims 2 to 7, further comprising the step of providing at least one radiating layer on the front surface of a stack, preferably after at least one membrane layer is provided, such that the pellicle assembly comprises a membrane comprising at least one membrane layer and at least one radiating layer. 9.A method according to any one of claims 2 to 8, wherein the method further comprises the step of providing at least one capping layer on the front surface of the stack, wherein the capping layer preferably comprises silicon oxide and / or silicon dioxide and / or silicon nitride. 10. A method according to any one of claims 2 to 9, wherein the method further comprises the step of providing a resist on the stack and the step of patterning the resist before selectively removing one or more portions from the back surface of the stack. 11. A method according to claim 10, wherein the method further comprises the step of selectively removing one or more portions from the back surface of the stack and / or the step of etching at least one portion of the stack during the step of selectively removing one or more portions of the stack to form a pellicle assembly. 12. A method according to claim 11, wherein the etching agent comprises phosphoric acid and / or hydrofluoric acid. 13. A method according to any one of claims 2 to 12, wherein the stack comprises a planar substrate and preferably at least one sacrificial layer. 14. A method according to claim 13, wherein the planar substrate is a wafer, optionally a silicon wafer. 15. A method according to claim 13 or 14, wherein at least one sacrificial layer comprises silicon nitride, silicon oxide, tetraethyl orthosilicate (TEOS), chemical silicon oxide, or thermal silicon oxide. 16. A method according to any one of claims 1 to 15, wherein the at least one membrane layer preferably comprises at least one amorphous silicon layer, or at least one silicon layer formed by crystallizing a MoSiNx layer, and / or the at least one protective layer comprises a cross-linked polymer, preferably a poly(p-xylylene) polymer, preferably Parylene or ProTEK® type material or KMPR. TMA method comprising a resist such as. 17. The method of any one of claims 8 to 16, wherein at least one membrane layer is provided to be disposed between at least one radiating layer and a face of a stack; preferably, at least one radiating layer is metallic. 18. The method of any one of claims 8 to 17, wherein at least one radiating layer comprises boron, Zr, Mo and / or Ru. 19. The method of any one of claims 8 to 18, wherein at least one radiating layer comprises a plurality of radiating sublayers, preferably, the radiating sublayers are metallic. 20. The method of claim 19, wherein the radiating layer comprises a zirconium-containing layer disposed between two boron-containing layers. 21. A method according to any one of claims 9 to 20, wherein at least one capping layer has a capping layer thickness, and at least one membrane layer has a membrane layer thickness, and the capping layer thickness is smaller than the membrane layer thickness. 22. A method according to any one of claims 9 to 21, further comprising the step of selectively removing at least one portion of at least one capping layer after selectively removing one or more portions of a stack to form a pellicle assembly. 23. A method according to any one of claims 1 to 22, wherein at least one membrane layer and / or at least one capping layer and / or at least one radiating layer further comprises at least one sacrificial layer. 24. A pellicle substrate comprising a stack having a front surface and a back surface, wherein one or more layers on the back surface of the stack are selectively removed to define a pellicle boundary region for holding the pellicle membrane before a layer forming at least a portion of the pellicle membrane is provided. 25.In claim 24, the pellicle substrate further comprises at least one protective layer on the front surface of the stack, preferably at least one protective layer is a cross-linked polymer, preferably a poly(p-xylylene) polymer, preferably Parylene or ProTEK® type material or KMPR. TM A pellicle substrate comprising a resist such as. 26. The pellicle substrate of claim 24 or 25, wherein the stack comprises a planar substrate and preferably at least one sacrificial layer; preferably, the planar substrate is a wafer, optionally a silicon wafer or an SOI wafer; and preferably, at least one sacrificial layer comprises silicon nitride. 27. A lithography apparatus comprising a pellicle assembly prepared according to any one of the methods of claims 1 to 23. 28. The method of claim 11 or 12, wherein, after etching, the pellicle membrane produced comprises a MoSiNx core layer having no additional functional cap layers, or a MoSiNix core layer having at least one surface covered with a native oxide layer. 29. A method according to claim 11 or 12, wherein, after etching and metal deposition, the stack is formed by a SiN / Ox, pSi pellicle core layer, a low stress nitride (LSN) layer on the front side, and a Ru cap layer on Mo deposited on the back side of the stack. 30. A pellicle substrate according to claim 24, comprising a pellicle core layer selected from a silicon-based material such as pSi, SiC, MoSi2 or MoSiNx, or a carbon-based material such as a graphene film or a carbon nanotube film. 31. A pellicle substrate according to claim 24, wherein the stack comprises two or more layers of SiO / MoSiNx / MoSi2, or layers of two or more layers of SiON / MoSiNx / SiON.

Claims

Claim 1 A method for manufacturing a membrane assembly for EUV lithography, the method comprising the step of providing a stack having a front surface and a back surface, wherein a layer forming at least a portion of a pellicle membrane is provided on the front surface of the stack after one or more etching steps defining a pellicle boundary that maintains the pellicle membrane on the back surface opposite to the front surface. Claim 2 delete Claim 3 A method according to claim 1, further comprising the step of providing at least one radiating layer on the front surface of a stack such that, after at least one membrane layer is provided, the pellicle assembly comprises a membrane including at least one membrane layer and at least one radiating layer. Claim 4 The method of claim 1 further comprises the step of providing at least one capping layer on the front surface of the stack, wherein the capping layer comprises silicon oxide and / or silicon dioxide and / or silicon nitride. Claim 5 A method according to claim 1, further comprising the steps of providing a resist on a stack and patterning the resist before selectively removing one or more portions from the back of the stack. Claim 6 The method of claim 5 further comprises the step of selectively removing one or more portions from the rear surface of the stack and / or the step of etching at least a portion of the stack during the step of selectively removing one or more portions of the stack to form a pellicle assembly. Claim 7 A method according to claim 1, wherein the stack comprises a planar substrate and at least one sacrificial layer. Claim 8 A method according to claim 7, wherein at least one sacrificial layer comprises silicon nitride, silicon oxide, tetraethyl orthosilicate (TEOS), chemical silicon oxide, or thermal silicon oxide. Claim 9 A method according to any one of claims 1 and 3 to 8, wherein the method further comprises the step of providing at least one protective layer on the front surface of the stack, wherein the at least one membrane layer comprises at least one amorphous silicon layer or at least one silicon layer formed by crystallizing a MoSiNx(x > 0) layer, and / or the at least one protective layer comprises a crosslinked polymer, a poly(p-xylylene) polymer, Parylene or a ProTEK® type material or a resist such as KMPRTM. Claim 10 A pellicle substrate comprising a stack having a front surface and a back surface, wherein one or more layers on the back surface of the stack opposite to the front surface are optionally removed to define a pellicle boundary region for retaining a pellicle membrane before a layer forming at least a portion of a pellicle membrane is provided on the front surface of the stack. Claim 11 In claim 10, the stack comprises a planar substrate and at least one sacrificial layer; the planar substrate is a wafer, optionally a silicon wafer or an SOI wafer; and the at least one sacrificial layer is a pellicle substrate comprising silicon nitride. Claim 12 A method according to claim 6, wherein, after etching, the generated pellicle membrane comprises a MoSiNx(x > 0) core layer having no additional functional cap layers, or a MoSiNix(x > 0) core layer having at least one surface covered with a native oxide layer. Claim 13 A method according to claim 6, wherein, after etching and metal deposition, the stack is formed by a SiN, SiOx(x > 0), pSi pellicle core layer on the front side, a low stress nitride (LSN) layer, and a Ru cap layer on Mo deposited on the back side of the stack. Claim 14 In claim 10, the substrate comprises a pellicle core layer selected from a silicon-based material such as pSi, SiC, MoSi2 or MoSiNx(x > 0), or a carbon-based material such as a graphene film or a carbon nanotube film. Claim 15 In claim 10, the stack comprises two or more layers of SiO / MoSiNx(x > 0) / MOSi2, or two or more layers of SiON / MoSiNx(x > 0) / SiON, a pellicle substrate. Claim 16 delete Claim 17 delete Claim 18 delete Claim 19 delete Claim 20 delete Claim 21 delete Claim 22 delete Claim 23 delete Claim 24 delete Claim 25 delete Claim 26 delete Claim 27 delete Claim 28 delete Claim 29 delete Claim 30 delete Claim 31 delete

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