Euv reticle stocker and method of operating the same

Abstract

An operating method (400, 410), a storage system (300, 600) and a clamping device (200, 500) for an EUV reticle stocker are provided. The required space for storing EUV reticles is significantly reduced while ensuring a high quality storage environment for the stored EUV reticles. A further aspect of the invention provides a stocker (700) for storing EUV reticles.

Description

Technical Field

[0001] This invention relates to a reservoir for EUV masks and a method of operating the reservoir. Background Technology

[0002] Photolithography is widely used as a key step in the manufacture of integrated circuits (ICs) and other semiconductor-related devices and / or structures. However, as the size of features manufactured by this process decreases, the importance of photolithography for producing micro-ICs or other devices and / or structures increases.

[0003] In photolithography, a geometric pattern is transferred from a photomask (often called a photomask) onto a substrate (e.g., a semiconductor wafer) using light, a photosensitive layer, and a subsequent etching step. Depending on the desired feature size on the substrate, and taking into account the Raleigh standard, the feature size of the photomask and the wavelength of the light used for pattern transfer need to be adjusted.

[0004] To reduce the minimum achievable feature size, extreme ultraviolet (EUV) radiation has been proposed. EUV radiation is electromagnetic radiation with wavelengths in the range of 5 nm to 20 nm, for example, in the range of 5 nm to 10 nm.

[0005] Any contamination of the photomask can degrade the imaging performance of the lithography process, and in more severe cases, may necessitate mask replacement. Photomasks are typically expensive, so any reduction in the frequency of mask replacement is beneficial. Furthermore, mask replacement is a time-consuming process that must be supported during the lithography process, thereby reducing its efficiency, which is undesirable.

[0006] For EUV applications, there may be particulate contamination with particle sizes smaller than 10 nm, as well as chemical contamination, for example, through the adsorption of volatile organic compounds.

[0007] Therefore, masks used in such EUV applications are typically stored in a storage reservoir and retrieved when needed to connect to a photolithography exposure device. Typically, the mask is contained in a double-shell container (double-layer cassette), which includes a so-called EUV outer shell (EOP) and an EUV inner shell (EIP).

[0008] For example, this double-layer box is described in further detail in US2019 / 0214287A1.

[0009] Because the acceptable levels of particulate contamination are very low, it is necessary to avoid friction between the mask and the container (which leads to wear and thus particle generation) and friction between container components relative to each other. Therefore, a typical EIP is designed to house a mask in such a way that the possibility of movement within it is extremely limited. The EIP is also equipped with additional mask-holding means to secure the mask inside the EIP. To prevent contamination, the EIP is designed to allow protective gas or vacuum to be applied to the mask. For this purpose, orifices equipped with filter material are typically provided to allow protective gas to enter from the EOP into the environment surrounding the mask contained within the respective EIP.

[0010] The EOP is equipped with an actuating means adapted to bias the mask fixing means of the EIP to a holding position, thereby securing the mask inside the EIP when the EOP is attached to the EIP. The EOP is also used to fix the two normally opposing parts of the EIP relative to each other to prevent wear caused by friction. Summary of the Invention

[0011] It should be understood that EIP components are movable relative to each other unless externally secured. To avoid wear caused by friction resulting from this movement, EOP typically provides this securing function for the EIP, while also providing protection against ambient air, which is necessary, for example, during transport between storage locations and processing tools that require masks for operation.

[0012] EOPs are quite large, resulting in storage tanks for EUV masks requiring significant space or "footprint." Furthermore, EOPs are made of polymeric materials, which are prone to wear and release volatile organic compounds.

[0013] This invention seeks to address these problems by providing methods, apparatus, and systems having the features according to the independent claims. Advantageous embodiments and additional features are provided in the dependent claims and discussed in the following description.

[0014] This invention reduces the space required for storing photomasks while ensuring at least the same level of contamination and damage protection as conventional systems. Chemical contamination from EOP releases during storage is prevented, and mechanical damage protection is improved compared to storing photomasks in a double-walled box. For example, EOPs may be vulnerable to damage during earthquakes; however, the device according to the invention is not fragile even under such challenging conditions, as will be understood from the following description.

[0015] One aspect to consider when developing this improved memory concept is the strong reluctance to change the way photomasks are supplied to lithography equipment, which is often the most complex and expensive part of a semiconductor manufacturing facility.

[0016] Therefore, since lithography equipment is generally suitable for receiving double-layer boxes, the means for supplying conventional double-layer boxes to lithography equipment is advantageously equipped with an improved mask reservoir.

[0017] In one aspect of the invention, a clamping device is provided for an EUV inner layer cartridge (EIP), the EIP comprising two or more components and including or adapted to include an EUV mask, wherein the clamping device is configured to fix the two or more components of the EIP and the mask relative to each other and to only partially cover the EIP. For example, the clamping device according to the invention covers only a portion of the outer surface of the EIP that is less than 90%, 80%, 75%, 50%, 25%, 20%, or 10% in total. Therefore, the clamping device allows, for example, air surrounding the clamping device to come into contact with the EIP, thereby avoiding, for example, the need for a precise means of supplying protective gas.

[0018] Note that clamping devices can also be used to hold EIP components together, even if this does not hold the mask. In this case, only the EIP components are fixed relative to each other.

[0019] Advantageously, the clamping device is also configured as a holding means acting on the EIP, the holding means being configured to secure the mask within the EIP when subjected to forces from outside the EIP, thereby fixing the mask within the EIP. Thus, the fixation of the mask within the EIP is achieved by the clamping device acting on the holding means provided on the EIP. This provides the advantage that existing systems can continue to be used without refurbishment, thereby avoiding costly investments.

[0020] Advantageously, the clamping element is primarily made of a metallic material, which preferably comprises at least 75%, 80%, 90%, 95%, or 99% of the total device volume and / or mass. This mitigates the aforementioned chemical contamination problems due to the release of polymeric materials. Consequently, the required amount of purge gas and the necessary mask replacement frequency can be reduced. Other possible materials with similar advantages are, for example, polycarbonate (PC), polyethyl ether ketone (PEEK), or cyclic olefin (co)polymers (COC / COP). These materials are characterized by particularly low release properties.

[0021] In an advantageous embodiment, the clamping device has two clamping elements, including an upper clamping element and a lower clamping element, which are configured to attach to each other while accommodating the EIP between them. Specifically, the movements required to assemble such a clamping device around the EIP are substantially perpendicular to the main surface of the EIP, and substantially no lateral movement relative to the EIP is required. This facilitates the assembly process and reduces the risk of friction-induced particle generation (wear).

[0022] Advantageously, the upper clamping element is configured to act as a holding means for the EIP to secure the mask within it. Therefore, it can replace or mimic the fixing function traditionally achieved by the EOP without the disadvantages of chemical contamination and space requirements.

[0023] In other embodiments, the clamping device includes a clamping element and one, two, or more fixing means, wherein the fixing means are biased toward a closed position and configured to move into an open position; wherein the clamping device is configured to be attachable to the EIP when the fixing means are in the open position, and to secure the EIP component and the mask relative to each other when the fixing means are in and / or enter the closed position. In other words, the clamping device is configured as a single clamping element or a one-piece clamping element including fixing means. When the clamping device is attached to the EIP, the fixing means act on the underside of the EIP and on the top side of the clamping element. Furthermore, the single clamping element provides the same functionality as the aforementioned upper clamping element. This one-piece embodiment is advantageous in terms of manipulation because only one device is needed to provide the same functionality. This one device is attached to the EIP from the top side. Therefore, attaching the clamping device to the EIP requires fewer manipulation steps compared to the two-piece embodiments described above.

[0024] Advantageously, the clamping device includes an actuator configured to act on the holding means when the clamping device is attached to the EIP.

[0025] Advantageously, the encapsulation volume of the clamping device is less than 130%, 120%, 110%, 105%, or even less than 100% of the encapsulation volume of the EIP to which the clamping device can be attached.

[0026] Specifically, the encapsulation volume of the clamping device is less than 130%, 120%, 110%, or 105% of the encapsulation volume of the EIP, thus significantly reducing the space footprint of the storage mask compared to storage within a double-layered box comprising both the EIP and EOP. As mentioned above, this also reduces the amount of purge gas required. For example, the encapsulation volume can be understood as describing the volume of the smallest possible cube that completely contains the corresponding object.

[0027] According to some embodiments, the clamping device may be equipped with an information-carrying element, such as an RFID device or a visually detectable code, such as a barcode, QR code, or other form of 1D or 2D code. This provides the advantage that information about the mask can be associated with the corresponding clamping device. Thus, a stored mask can be identified, for example, simply by identifying the clamping device associated with the stored mask.

[0028] Furthermore, this information can be used for tracking purposes, such as counting the number of storage operations performed using a given clamping device. This is useful in determining the appropriate time for cleaning or replacement processes or functional testing.

[0029] In some embodiments, sensors for monitoring certain conditions during storage and in the tank are included in the clamping device; these conditions include, for example, humidity, temperature, pressure, acceleration, or the concentration of certain chemicals in the storage air. This provides the advantage of knowing the influencing factors the mask experiences throughout its storage history, and thus can improve the overall productivity of the production facility where the invention is implemented.

[0030] This information can be stored and processed in a memory and / or processor provided in the clamping device, or in a component of a machine or tool that processes the storage system according to the invention.

[0031] In another aspect, the present invention provides a storage system including the clamping device and the EIP as described above. The EIP includes two or more components configured to receive an EUV mask and includes a holding means configured to secure the mask contained within the EIP when the holding means are acted upon from outside the EIP. The clamping device is attached to the EIP to secure the two or more components of the EIP relative to each other and acts on the holding means to secure the mask within the EIP. Therefore, wear is substantially avoided, and contamination of the mask by particles within the relevant size range is minimized.

[0032] Typically, the retaining means are configured in the form of one or more pistons passing through one of the EIP components. Each piston is elastically biased to a retracted position and adapted to apply a normal force to the mask when subjected to an action from outside the EIP. Simultaneously, the retaining means seal against the EIP component it penetrates to protect the mask stored within the EIP from contamination by contaminants from outside the EIP.

[0033] In a preferred embodiment, the encapsulation volume of the storage system is less than 130%, 120%, 110%, or 105% of the encapsulation volume of the EIP. Therefore, compared to conventional storage systems in a two-cell form including both EIP and EOP, the space required for the storage mask is significantly reduced.

[0034] Another aspect of the invention provides a method for operating an EUV mask reservoir, comprising storing a mask in the mask reservoir and retrieving a mask from the mask reservoir, wherein storing includes moving a storage system containing the mask according to the invention to a storage location within the EUV mask reservoir; and retrieving includes removing the storage system containing the mask according to the invention from its storage location. This reduces the space required to store the mask compared to conventional storage methods.

[0035] Specifically, prior to the step of moving to the storage location, the storage process further includes the following steps: receiving a double-layer box from outside the reservoir, the double-layer box comprising an EUV outer layer box (EOP) and an EIP containing an EUV mask, wherein the EIP is completely contained within the EOP; opening the EOP; and attaching clamping devices to the EIP to secure the EIP components relative to each other and acting on holding means disposed within the EIP such that the mask is secured relative to the EIP, thereby providing the storage system. In such an embodiment, the storage system is provided by the improved reservoir itself, allowing the reservoir to be used directly in conjunction with existing manufacturing processes without substantially altering any process steps performed outside the reservoir.

[0036] In a preferred embodiment, receiving the double-layer box includes receiving the double-layer box on the outward-facing side of the inlet terminal including the airlock, opening a first gate of the airlock, moving the double-layer box into the airlock, closing the first gate, purifying the internal volume of the airlock, opening a second gate of the airlock, moving the double-layer box through the second gate to the inward-facing side of the inlet terminal, and closing the second gate. In other words, the double-layer box passes through the airlock from the outward-facing side of the inlet terminal to the inward-facing side, including purifying the internal volume of the airlock while the double-layer box is inside the airlock. This provides the advantage of avoiding reservoir contamination.

[0037] Opening the EOP may include unlocking the EOP, removing the EOP from around the EIP, and storing the EOP in an EOP buffer. The EOP buffer is preferably located separately from the storage location of the aforementioned storage system to prevent cross-contamination from the outside of the EOP to the EIP. Therefore, while reducing the space required for storing the mask, stringent cleanliness requirements can be met.

[0038] Retrieving the mask after removing the storage system from its storage location preferably also includes separating the clamping device from the EIP, assembling the EOP around the EIP to secure the EIP components and the mask housed within the EIP relative to each other, forming a double-layer box, and preferably transferring the double-layer box to the outside of the reservoir by passing it through an airlock to prevent air contamination of the reservoir. This provides the advantage that standard double-layer boxes can be used in conjunction with production processes in the facility, allowing conventional process equipment to benefit from the improved storage conditions provided by this invention.

[0039] The EOPs used for this assembly can preferably be retrieved from the aforementioned EOP buffer. This provides the advantage that not every mask to be stored requires an EOP, while ensuring a timely supply of any masks needed for the manufacturing process. In other words, the number of stored masks can significantly exceed the number of EOPs supplied. Conversely, at any given time, only those masks required outside the buffer require an EOP during that time period.

[0040] Preferably, during any steps performed when the mask is not fixed relative to the EIP, it is ensured that the mask and / or EIP components do not move relative to each other in order to prevent wear and corresponding particle generation.

[0041] When the clamping device is equipped with the information-carrying element described above, the method may advantageously include one or more steps in which the information carried by the clamping device is read, written, deleted, or altered. During these steps, information identifying the mask associated with the manipulated clamping device, the storage conditions experienced by the mask, or other information can be used to control the mask reservoir or other tools, machines, or equipment to provide overall performance improvements to the production facility.

[0042] The method may also include reading, receiving, or otherwise collecting information provided by one or more sensors optionally provided by the clamping device to monitor the history of storage conditions experienced by the mask. This provides the advantage that, for example, those masks that may have quality defects can be inspected before being used in the manufacture of semiconductor products to ensure the integrity of the semiconductor products. Therefore, the production of defective products is minimized.

[0043] In another aspect of the invention, a reservoir is provided for storing at least one EUV mask, wherein each of the at least one mask is stored or adapted and configured to be stored in a corresponding EUV inner layer cassette (EIP), wherein the EIP includes two or more EIP components fixed relative to each other by clamping means, wherein the EIP includes holding means configured to fix the mask stored inside the EIP relative to the EIP when subjected to an action from outside the EIP, wherein the clamping means act on the holding means to fix the mask stored within the EIP, the reservoir comprising: a loading port (also referred to as an inlet terminal in the language of this disclosure), which includes an airlock and an assembler; and a storage unit configured to store EUV masks. The device comprises an IP, each EIP secured by a clamping device and each EIP containing a mask; and a manipulator configured to move and remove the clamped EIP containing the mask from a storage location within a reservoir; wherein an airlock is configured to receive from outside the reservoir a double-layered box comprising an EUV outer layer box (EOP) and the EIP containing the mask, wherein the EOP acts as a holding means; and an assembler configured to open the EOP without causing movement of the EIP components and the mask relative to each other; attach the clamping device to and remove the clamping device from the EIP without causing movement of the EIP components and the mask relative to each other; and assemble the EOP around an unclamped EIP.

[0044] Advantageously, the reservoir also includes an EOP buffer reservoir, which is configured to store multiple EOPs in controlled air using a manipulation means configured to place EOPs into the EOP buffer reservoir and retrieve EOPs from the EOP buffer reservoir.

[0045] In other words, the reservoir is suitable for implementing the above method and therefore benefits from the same advantages as the above method. Attached Figure Description

[0046] The advantages and other aspects of the invention will now be discussed in more detail with reference to the accompanying drawings, wherein

[0047] Figure 1 Two different embodiments of the EIP that can be implemented in conjunction with the present invention are shown;

[0048] Figure 2 A perspective view schematically illustrates an advantageous embodiment of the clamping device according to the invention;

[0049] Figure 2A A top view of the upper clamping element for two advantageous embodiments of the two-piece clamping device according to the invention is shown;

[0050] Figure 3A perspective view of a preferred embodiment of the storage system according to the present invention is shown schematically;

[0051] Figure 4A and Figure 4B A flowchart illustrating a preferred embodiment of the operation method of the EUV mask reservoir according to the present invention is shown;

[0052] Figure 5A and Figure 5B Another advantageous embodiment of the clamping device according to the invention is illustrated schematically;

[0053] Figure 6 A schematic representation of a preferred embodiment of a storage system including a one-piece clamping device according to the present invention is shown in perspective and plan views; and

[0054] Figure 7 An advantageous embodiment of the mask reservoir according to the invention is illustrated schematically. Detailed Implementation

[0055] Figure 1 Two embodiments A and B of a conventional EIP, generally designated 100, are shown. Each EIP 100 includes an upper component 110 and a lower component 120. The upper component 110 includes one or more orifices 112, retaining means 114, and pressure points 116.

[0056] The retaining means 114 is configured as four pistons, biased to the retracted position by elastic elements, and connected to the upper part 110 in a sealed manner by elastic sealing means to prevent particulate contaminants from entering the interior of the EIP.

[0057] The orifice 112 is equipped with filter material to prevent particulate contaminants from entering the interior of the EIP while providing a passage for protective gases and / or purge gases such as nitrogen.

[0058] Pressure point 116 is configured to fix the two components 110, 120 relative to each other, and retaining means are configured to fix the mask inside the EIP when acted from outside the EIP.

[0059] A pressure point similar to pressure point 116 on the upper component 110 can also be set on the lower component 120.

[0060] In embodiment A of EIP 100, pressure point 116 and holding means 114 are spatially separated, while in embodiment B, holding means 114 and pressure point 116 are located in the same area and extend through pressure point 116.

[0061] exist Figure 2 and Figure 2AThe image schematically depicts a clamping device 200 that can be used in conjunction with embodiments A and B of EIP 100.

[0062] The clamping device 200 includes two elements 210 and 220 made of sheet metal, one of which is an upper clamping element 210 having an aperture 212 that substantially corresponds in position to one or more apertures 112 of the EIP, and is configured to mate with the EIP 100. In the language of this disclosure, the portion of the EIP 100 that corresponds in position to the aperture 212 is referred to as “uncovered,” while specific portions of the EIP 100 that are in contact with, directly opposite to, or located below the material surface of the clamping device are considered as “covered.” Thus, according to the invention, the clamping device 200 is configured to only partially cover the EIP 100. The aperture 212 may specifically occupy more than 10%, 20%, 25%, 50%, 75%, 80%, or 90% of the surface area of ​​the upper clamping element 210. Furthermore, similar apertures may also be provided in the lower clamping element 220 (not shown in the figures). In addition, the side-facing surface of EIP 100 is also considered "uncovered", which does not correspond to either the upper clamping element 210 or the lower clamping element 220.

[0063] The second element 220 forming the lower clamping element is substantially flat and corresponds to the upper clamping element 210 in size, shape and profile.

[0064] The upper clamping element 210 and the lower clamping element 220 are attachable to each other and configured to accommodate and secure the EIP 100 between them when attached. For this purpose, both the upper and lower clamping elements are equipped with a pressing means 216 configured to press corresponding pressure points 116 of the upper part 110 and the lower part 120 of the EIP 100 to fix the EIP parts 110, 120 relative to each other.

[0065] Furthermore, the actuator 214 is provided with an upper clamping element 210 for embodiment A of EIP 100, which is configured to act on the holding means 114 of the upper part 110 of embodiment A of EIP 100 when the clamping device 200 is attached to EIP 100.

[0066] In the clamping device 200 suitable for use with embodiment B of EIP 100, the pressing means 216 simultaneously functions as the actuator 214. Therefore, each pressing means 216 also constitutes an actuator 214.

[0067] For the two embodiments shown, the clamping device 200 fixes the mask contained in the EIP 100 relative to the EIP 100 by means 114 acting on the EIP 100.

[0068] The extrusion means 216 and the actuator 214 are configured in the form of tongue-shaped cuts and can be constructed to apply predetermined forces to the pressure point 116 and the holding means 114, respectively. Advantageously, the extrusion means 216 is configured to apply a predetermined force to each of the pressure points 116. In the clamping device used with embodiment A of EIP 100, the force applied to the pressure point may be different from the predetermined force applied by the actuator 214 to the holding means 114. Thus, the forces applied to the holding means 114 and the pressure point 116 can be adapted to the forces required to fix the respective components relative to each other. Typically, the force required to fix the mask within the EIP is less than the force required to fix the upper component 110 relative to the lower component 120. Therefore, the tongue-shaped cut forming the actuator 214 can be longer and / or narrower than the cut forming the extrusion means 216.

[0069] In a clamping device suitable for use with Embodiment B of EIP 100, different forces can be applied to the pressure point 116 and the holding means 114, for example, by providing an additional tongue-shaped slit (not shown) within the compression means 216, such that a smaller force can be applied to the holding means 114 compared to the force applied to the pressure point 116. In other words, even if the pressure point 116 and the holding means 114 in Embodiment B of EIP 100 are very close, the compression means 216 and the actuator 214 can still be provided separately from each other.

[0070] The upper clamping element 210 is provided with a fixing means 202, which is configured to fix the upper clamping element 210 to the lower clamping element 220 in order to set the clamping device 200. Figure 2 and Figure 2A In the example shown, the fixing means 202 is provided in the form of a latch, but other forms of fixing means are also possible.

[0071] exist Figure 3 The image shows a storage system 300 in an assembled state, including an EIP 100 and a two-piece clamping device 200 having an upper clamping element 210 and a lower clamping element 220. The lower clamping element 220 is in... Figure 3 It is not visible in the middle because it is covered by EIP100.

[0072] exist Figure 5A and Figure 5B Another advantageous embodiment of the clamping device 500 is schematically shown in perspective and plan view.

[0073] and Figure 2 and Figure 2ACompared to the clamping device 200 shown, the clamping device 500 includes only one clamping element with at least two retaining means 502. Furthermore, one or more pressing means 516 are provided, configured to press corresponding pressure points 116 on the upper part 110 of the EIP 100 to fix the EIP parts 110, 120 relative to each other. The retaining means 502 are configured to press the top side of the clamping element 500 and the underside of the lower part 120 of the EIP 100 when the clamping device 500 is attached to the EIP 100. Similar to the clamping device 200, an actuator 514 is provided in the clamping device 500 to secure the mask within the EIP 100. When the clamping device 500 is attached to the EIP 100, the mask is secured within the EIP 100 through the interaction between the actuator 514 and the retaining means 114 of the EIP 100.

[0074] Notice, Figure 5A and Figure 5B The clamping device 500 shown is adapted for use with embodiment A of EIP 100. However, it should be understood that a similar one-piece clamping device 500 may be provided for embodiment B of EIP 100.

[0075] exist Figure 5A In this embodiment, the fixing means 502 is shown in the closed position. In this particular embodiment, the fixing means 502 are disposed on both sides of the clamping device 500, essentially in the form of leaf springs with operating and fixing elements. When attached to the EIP 100, the fixing elements of the fixing means 502 perform the aforementioned functions of pressing the top side of the clamping element and the lower side of the lower part 120 of the EIP 100.

[0076] exist Figure 5B In the diagram, the fixing means 502 is shown in the open position. In this position, the fixing means 502 is spaced apart from the clamping elements such that the space between the fixing elements 502 on two opposite sides of the clamping device 500 is large enough for the EIP 100 to move between them. Therefore, when the fixing means 502 is in the open position, the clamping device 500 can be attached to the EIP 100.

[0077] The leaf spring type fixing means 502 is offset against the closed position, so that in order to attach to EIP 100, a lateral force must be applied to the fixing means 502 to bring them into the open position.

[0078] The clamping element of the clamping device 500 is preferably made of a metal sheet, while the fixing means 502 may be configured as a leaf spring of metal, plastic or any other suitable single material or combination of materials.

[0079] The actuator 514 and the extrusion means 516 are preferably configured in the form of a tongue-shaped cut, substantially as a combination Figure 2 The above description of the embodiments.

[0080] When the clamping device 500 is attached to the EIP 100, the retaining means 502 is forced into the open position. This can be achieved by pulling the operating element of the retaining means in a substantially lateral direction relative to the clamping device 500. The clamping device 500, with the retaining means 502 held in the open position, is then placed on the EIP and pressed downward against the EIP with a preload force. As a result, the pressing means 516 and the actuator 514 of the clamping device 500 come into contact with the pressure point 116 and the retaining means 114 of the EIP 100, respectively. Thus, once the preload force is applied, the EIP components 110, 120 and the mask contained within the EIP 100 are fixed relative to each other through the interaction between the clamping device 500 and the EIP 100.

[0081] The preload force is selected such that the clamping device 500 moves toward the EIP 100 in the normal direction relative to the main extension plane of the EIP 100 to such an extent that the fixing means 502 can be released to the closed position without contacting any part of the EIP 100. Therefore, as long as the preload force is applied, the fixing means 502 will not cause friction when moving to the closed position. Thus, particle generation is effectively prevented.

[0082] As long as a preload force is applied to the clamping device 500, the fixing means 502 remains spaced apart from the EIP 100 and the top side of the clamping device 500 in the normal direction.

[0083] Once the retaining means 502 has reached the closed position, the applied preload force is released, causing the clamping device 500 to move away from the EIP 100 until the retaining means 502 restricts further displacement of the clamping device 500 relative to the EIP 100 by pressing the top side of the clamping device and the lower side of the lower part 120 of the EIP 100.

[0084] After the preload force has been removed from the top side of the clamping device 500, the actuator 514 and the pressing means 516 still apply normal fixing forces to the holding means 114 and the pressure points 116, respectively. These fixing forces are slightly less than the preload force. However, both the actuator 516 and the holding means 514 are designed such that the fixing force generated by each of them is sufficient to hold the mask within the EIP 100 and to hold the components 110, 120 of the EIP 100 relative to each other. For example, the pressing means 516 of a clamping element 500 jointly or individually apply a normal fixing force at each pressure point 116 in the range of 1N to 100N, preferably in the range of 5N to 50N, for example, about 20N ± 5N, for example, 17N. This common fixing force is preferably evenly distributed over the entirety of the individual pressing means 516. In the illustrated example, since the clamping device 500 provides four pressing means 516, one-quarter of the common fixing force is applied to each pressure point 116.

[0085] As described above, the retaining force applied to the mask by the retaining means 114 is preferably less than the retaining force applied to the EIP components 110, 120 by the pressure point 116. For example, the retaining force applied jointly to the retaining means 114 or individually to each retaining means 114 can be selected from the range of 1N to 100N, preferably from the range of 5N to 50N, and can reach, for example, about 20N ± 5N, such as 17N. In a similar manner to that described with reference to the extrusion means 516, the force is preferably evenly distributed across all the provided actuators 514.

[0086] As described above, the one-piece clamping device 500 is not limited to use with embodiment A of EIP 100. Different configurations are also provided according to this disclosure, for example, allowing the one-piece clamping device 500 to be used with embodiment B of EIP 100. Those embodiments of the clamping device 500 that can be used with embodiment B of EIP 100 substantially correspond to the aforementioned clamping device 200 that can be used with embodiment B of EIP 100, but are configured in a form similar to the one-piece clamping device 500.

[0087] It should be understood that the one-piece clamping device 500 covers less surface of the EIP 100 compared to the two-piece clamping device 200, because it substantially leaves the entire lower part 120 of the EIP 100 uncovered. Therefore, the clamping device 500, having an orifice 212 of the same size as the clamping device 200, substantially covers less of the EIP 100. For example, when attached to the EIP 100, the clamping device 500 leaves at least 50%, 60%, 70%, 80%, or 90% of the EIP 100 uncovered. In some embodiments, the clamping device 500 (or 200) leaves at least the orifice 112 of the EIP 100 uncovered, such that fluid passage from the atmosphere surrounding the clamping device 500 (or 200) toward the orifice 112 is substantially unobstructed.

[0088] Figure 6 This is a schematic diagram of a storage system 600, each storage system including an EIP 100 as described above and a clamping device 500. The clamping device 500 has a retaining means 502 in a closed position, and a pressing means 516 acts on a pressure point 116 to fix the EIP components 110, 120 relative to each other. An actuator 514 acts on a holding means 114 to fix a mask within the EIP 100.

[0089] Similar to the two-piece clamping device 200, the one-piece clamping device 500, suitable for use with embodiment B of EIP 100, has a pressing means 516 that also functions as an actuator 514. Like the clamping device 200, the actuator 514 of the clamping device 500 can also be disposed separately from the pressing means 516, for example, in the form of a tongue-shaped cut within the pressing means 516, or in the form of a cut extending in the opposite direction to the pressing means 516. These modifications are not shown in the figures but provide the advantage that the force applied to the pressure point 116 can be adjusted separately from the force acting on the holding means 114 of the EIP 100.

[0090] As from Figure 3 and Figure 6 It can be inferred from this that the clamping devices 200 and 500 have small dimensions. Therefore, the storage systems 300 and 600 occupy essentially the same volume as the EIP 100 itself.

[0091] exist Figure 4A The preferred method of operating the mask reservoir 700 for storing masks is illustrated in the flowchart and is uniformly indicated by reference numeral 400. Figure 7 The corresponding mask reservoir is schematically depicted.

[0092] The following will address the question regarding... Figure 2 and 2AThe method is described using the clamping device 200 discussed. However, it should be understood that when using the clamping device 500 to provide the storage system 600 as described above, corresponding steps can be taken.

[0093] In step 401, a double-layer box comprising an EUV outer layer box (EOP) 150 and an EIP 100 contained within the EOP 150 is received from outside the reservoir 700. The double-layer box is received at the outward-facing side of the inlet terminal, including an airlock 710, and passes through the airlock 710 to the inward-facing side of the inlet terminal. During passage through the airlock 710, the internal volume of the airlock 710 is purified, thereby ensuring that the air inside the mask reservoir 700 is not adversely affected by receiving the double-layer box.

[0094] Purifying the airlock 710 may include purging the airlock 710, flushing the airlock with a fluid such as a gas, especially an inert gas, and / or purging the airlock with a fluid, especially an inert gas.

[0095] In step 402, the double-layer box is opened. In this example, opening the double-layer box includes unlocking EOP 150, removing EOP 150 from its position surrounding EIP 100, and moving EOP 150 to EOP buffer reserve 750, where EOP 150 can be stored until needed again. When EOP 150 is removed from EIP 100, pressure point 116 and retaining means 114 are no longer activated. Therefore, at this point, EIP components 110, 120 and the mask contained therein are no longer fixed relative to each other.

[0096] In step 403, the clamping device 200 is attached to the EIP 100. This provides, for example... Figure 3 The storage system 300 is shown. The attachment clamping device 200 can be specifically implemented by placing the EIP 100 on the lower clamping element 220, then covering the EIP 100 with the upper clamping element 210, and attaching the lower and upper clamping elements to each other. Preferably, the EIP 100 is placed on the lower clamping element 220 and covered with the upper clamping element 210 in such a way that essentially only normal forces are applied to the EIP 100, and torsional and lateral forces are avoided. Once the clamping device 200 is installed on the EIP 100, the fixing function performed by the EOP 150 before the double-layer box is opened is effectively restored or mimicked by the clamping device 200.

[0097] When using the one-piece clamping device 500, step 403 of attaching the clamping device is performed in a slightly different manner. In this case, the fixing means 502 of the clamping device 500 is forced into position as follows: Figure 5BThe open position is shown. Then, the clamping device 500 is moved onto the EIP 100 and pressed against the EIP 100 with a predetermined preload force in a direction perpendicular to the main extension plane of the clamping device 500 (“normal direction”). Then, the retaining means 502 is released to enter the closed position, and the preload force is released from the clamping device 500. The storage system 600 as described above is thus formed.

[0098] In step 404, the storage systems 300 and 600 are moved to the storage location within the mask reservoir.

[0099] All steps, especially steps 402 and 403, are performed in such a way that the mask contained in EIP 100 does not move relative to EIP 100 in order to prevent friction from causing particle generation, as described above.

[0100] exist Figure 4B The preferred method of operating the mask reservoir for retrieving the mask is illustrated in a flowchart and is uniformly indicated by reference numeral 410.

[0101] In step 411, the storage system 300 is removed from its storage location.

[0102] In step 412, the clamping device 200 is removed from EIP 100 to disassemble the storage system 300. For this purpose, the upper clamping element 210 and the lower clamping element 220 are separated from each other, and the upper clamping element 210 is lifted away from EIP 100, thereby releasing pressure point 116 and holding means 114. At this point, the mask is no longer securely held within EIP 100.

[0103] Next, when the storage system 600 is disassembled, step 412 is performed in a slightly modified manner: the clamping device 500 is removed from the EIP 100 by first applying a preload force to the clamping device 500 so that the retaining means 502 is no longer in contact with the top side of the EIP 100 or the clamping device 500. Then, the retaining means 502 is forced into the open position, and the preload force is released. The clamping device 500 is then lifted away from the EIP 100, thereby releasing the pressure point 116 and the retaining means 114.

[0104] When using the one-piece clamping device 500, steps 403 and 412 can be performed without moving the EIP 100 at all. This can be achieved by leaving the EIP 100 on the lower part of the EOP 150 when attaching the clamping device 500 to the EIP 100, or by placing it on the lower part of the EOP 150 before removing the clamping device 500. This is particularly advantageous because it effectively prevents relative movement of the EIP parts 110, 120 and the mask, respectively.

[0105] In step 413, EOP 150 is retrieved from EOP buffer reserve 750 and assembled around EIP 100 to provide a double-layer box. When the double-layer box is fully assembled, the fixing function implemented by clamping device 200 during storage is provided by the EOP.

[0106] In step 414, the double-walled box formed in step 413 is conveyed to the outside of the reservoir 700. This may include allowing the double-walled box to pass through the aforementioned airlock 710 to the outward-facing side of the inlet terminal. During the passage of the double-walled box, the airlock 710 may be purged or flushed to prevent contaminants from entering the inlet terminal.

[0107] like Figure 7 As shown, the mask plate reservoir 700 includes the previously mentioned airlock 710, an assembler 720 configured to perform steps 402, 403, 412, and 413 of methods 400 and 410 described above, an EOP buffer reservoir 750 in which multiple EOPs 150 can be stored, and a storage unit 740 in which storage systems 300 and 600 can be stored in multiple storage locations 742. The reservoir 700 is provided with a manipulator 730 for moving the storage systems 300 and 600 to their respective storage locations 742 and removing them from their respective storage locations 742.

[0108] It should be noted that the number of storage locations 742 can substantially exceed the number of EOP150s that can be stored in the EOP buffer reserve 750. As mentioned above, only masks required outside the reservoir 700 require EOP150. Therefore, a certain (small) number of EOP150s are stored in the EOP buffer reserve 750 so that double-layer boxes can be assembled according to the demand for masks. However, since not all masks are usually needed at the same time, it is not necessary to store EOP150 for each mask stored in the storage unit 740.

[0109] exist Figure 2 , Figure 2A and Figure 5A In addition, the clamping devices 200 and 500 are provided with recording elements 218 and 518 (shown schematically), which include identification devices such as RFID devices and one or more sensors. The RFID devices 218 and 518 are information-carrying elements provided with identification numbers, so that each clamping device 200 and 500 can be distinguished from other clamping devices 200 and 500 by reading the RFID devices 218 and 518.

[0110] One or more sensors, including recording elements 218 and 518, are configured to detect or measure, for example, the temperature and composition of the air surrounding the clamping devices 200 and 500, the pressure acting on the clamping devices 200 and 500, and / or acceleration. In this example, recording elements 218 and 518 are also configured to store readings from one or more sensors and / or make these readings available for further processing.

[0111] For example, when clamping devices 200, 500 are equipped with RFID devices 218, 518, method 400 may include providing an association between a mask stored in conjunction with a clamping device 200, 500 and an identification number provided by the RFID device 218, 518 of the clamping device 200, 500. This association may be stored, for example, in the central memory of a mask reservoir and / or within a central computing device in the production facility. This provides the advantage that the mask can be identified by the clamping device 200, 500 used for its storage, and therefore remains identifiable while securely contained within the corresponding EIP 100.

[0112] The method may also include collecting data from one or more sensors and using the data, for example, to assess whether further action is needed, such as examining the retrieved mask.

[0113] Advantageously, method 410 then uses the RFID devices 218 and 518 of the clamping devices 200 and 500 to retrieve the mask associated with the clamping devices 200 and 500. This allows for the implementation of a verification mechanism. For example, it is possible to identify the mask to be retrieved from the reservoir 700 given a storage location 742 within the reservoir 700. When the mask is retrieved from this storage location 742, the RFID devices 218 and 518 of the clamping devices 200 and 500 can be read, and the association between the identification number of the clamping devices 200 and 500 and the stored mask can be checked to verify that the correct mask is being retrieved. If the identification of the mask stored at a particular storage location differs from that of the mask associated with the clamping devices 200 and 500, an identification procedure is triggered, and a warning signal can be generated, preventing the mask from being used in production until its identification has been verified. This provides the advantage of higher overall reliability in mask identification.

[0114] Another advantage of this association between the mask and the corresponding clamping devices 200, 500 is that the mask remains identifiable even if it has been randomly removed from its respective storage location. This could happen, for example, during an earthquake or similar uncontrollable event. In conventional methods and systems, masks may have to be removed from their respective EIPs for identification, or the conventional storage system may even be compromised in such cases. Therefore, the currently disclosed invention provides a more secure storage environment for EUV masks with improved traceability.

Claims

1. A clamping device for an EUV inner pod (100), characterized in that The EUV inner cassette (100) comprises two or more components and contains an EUV reticle, wherein the clamping device (500) is configured to fix the two or more components (110, 120) and the reticle of the EUV inner cassette (100) relative to each other; and covers the EUV inner cassette (100) only partially, wherein the clamping device (500) covers less than 90% of the total of the outer surface of the EUV inner cassette (100), and wherein the enclosed volume of the clamping device (500) is less than 100% of the enclosed volume of the EUV inner cassette (100) to which the clamping device (500) is attachable, wherein the clamping device (500) comprises one clamping element having one, two or more fixation means (502).

2. The clamping device (500) according to claim 1, characterized in that is further configured to act on the holding means (114) of the EUV inner cassette (100), the holding means (114) being configured to fix the reticle therein when acted upon from outside the EUV inner cassette (100) to fix the reticle within the EUV inner cassette (100).

3. The clamping device (500) according to claim 1 or 2, characterized in that comprises at least 75%, 80%, 90%, 95% or 99% of a metal material relative to its mass and / or volume.

4. The clamping device (500) according to claim 2, characterized in that The fixation means (502) are biased towards a closed position and configured to be moved into an open position; wherein the clamping device (500) is configured to be attachable to the EUV inner cassette (100) when the fixation means are in the open position and to fix the two or more components (110, 120) and the reticle of the EUV inner cassette relative to each other when the fixation means (502) are in the closed position.

5. The clamping device (500) according to claim 4, characterized in that One clamping element comprises an actuator (514) configured to act on the holding means (114) when the clamping device (500) is attached to the EUV inner cassette (100).

6. The clamping device (500) according to claim 1 or 2, characterized in that further comprises a recording element (518) comprising one or more components comprising: an information carrying element configured for identifying the clamping device (500), a temperature sensor, a pressure sensor, a concentration sensor configured to detect or measure a concentration of one or more chemical substances in the air surrounding the clamping device (500), and / or an acceleration sensor, wherein the recording element is configured to store and / or make available information generated using one or more components of the recording element (518).

7. A storage system (600) characterized by comprises the clamping device (500) and the EUV inner cassette (100) according to any of the preceding claims, wherein the EUV inner cassette (100) is configured to house an EUV reticle and comprises two or more components (110, 120) and holding means (114) configured to fix the reticle when acted upon from outside the EUV inner cassette (100); and wherein the clamping device (500) is attachable to the EUV inner cassette (100) to fix the two or more components (110, 120) relative to each other and to act on the holding means (114).

8. The storage system (600) according to claim 7, characterized by , the encapsulation volume of which is less than 130%, 120%, 110% or 105% of the encapsulation volume of the EUV inner cassette (100).

9. A method of operating an EUV reticle stocker (700), characterized in that , comprising storing (400) an EUV reticle in a reticle stocker and retrieving (410) a reticle from the reticle stocker (700), wherein storing (400) comprises moving (404) the storage system (600) containing the reticle according to claim 7 or 8 to a storage location (742) within the EUV reticle stocker (700); and retrieving (410) comprises removing (411) the storage system (600) containing the reticle according to claim 7 or 8 from its storage location (742).

10. The method of claim 9, wherein, Before the step of moving (404) to the storage location (742), storing (400) further comprises the steps of: receiving (401) a double cassette from outside the stocker (700), the double cassette comprising an EUV outer cassette (150) and an EUV inner cassette (100) containing an EUV reticle, wherein the EUV inner cassette (100) is completely contained within the EUV outer cassette (150); opening (402) the EUV outer cassette; and attaching (403) the clamping device (500) to the EUV inner cassette (100) to fix two or more components (110, 120) of the EUV inner cassette relative to each other and to act on the holding means (114) comprised in the EUV inner cassette (100) to fix the reticle relative to the EUV inner cassette (100) to provide the storage system (600).

11. The method of claim 10, wherein, receiving (401) the double cassette comprises receiving the double cassette at an outwardly facing side of an entry terminal comprising an airlock (710), opening a first shutter of the airlock (710), moving the double cassette into the airlock (710), closing the first shutter, purging an inner volume of the airlock (710), opening a second shutter of the airlock (710), moving the double cassette through the second shutter to an inwardly facing side of the entry terminal, and closing the second shutter.

12. The method of claim 10, wherein opening (402) the EUV outer cassette (150) comprises unlocking the EUV outer cassette (150), removing the EUV outer cassette (150) from around the EUV inner cassette (100), and storing the EUV outer cassette (150) in an EUV outer cassette buffer stock (750).

13. The method according to any one of claims 9 to 12, characterized in that, After the step of removing (411) from the storage location (742), retrieving (410) further comprises the steps of: detaching (412) the clamping device (500) from the EUV inner cassette (100); assembling (413) the EUV outer cassette (150) around the EUV inner cassette (100) to fix the two or more components (110, 120) of the EUV inner cassette and the reticle contained within the EUV inner cassette (100) relative to each other, thereby forming a double cassette; and transferring (414) the double cassette to outside the stocker (700).

14. A stocker (700) for storing at least one EUV reticle, characterized in that Each of the at least one mask blank is stored in a respective EUV inner pod (100), wherein the EUV inner pod (100) comprises two or more components (110, 120) which are fixed relative to each other by the clamping device (500) according to any one of claims 1 to 6, wherein the EUV inner pod (100) comprises holding means (114) configured to fix the mask blank stored inside the EUV inner pod (100) relative to the EUV inner pod (100) when subjected to an action from outside the EUV inner pod (100), wherein the clamping device (500) acts on the holding means (114) to fix the mask blank stored inside the EUV inner pod (100), the stocker (700) comprises: a load port comprising a gas lock (710) and an assembler (720); a storage unit (740) configured to store the EUV inner pods (100) in respective storage locations (742), each EUV inner pod (100) being fixed by one clamping device (500) and each EUV inner pod (100) containing one mask blank; and a manipulator (730) configured to move the clamped EUV inner pod (100) containing the mask blank to and from a respective storage location (742) within the storage unit (740) of the stocker (700); wherein: the gas lock (710) is configured to receive from outside the stocker (700) a double pod comprising an EUV outer pod (150) and an EUV inner pod (100) containing a mask blank, wherein the EUV outer pod (150) acts on the holding means (114); and the assembler (720) is configured to open the EUV outer pod (150) without causing movement of the two or more components (110, 120) of the EUV inner pod and the mask blank relative to each other; to attach and remove the clamping device (500) to and from the EUV inner pod (100) without causing movement of the two or more components (110, 120) of the EUV inner pod and the mask blank relative to each other; and to assemble the EUV outer pod (150) around the unclamped EUV inner pod (100).

15. The reserve (700) according to claim 14, characterized in that, Further comprising an EUV outer pod buffer stock (750) configured to store a plurality of EUV outer pods (150) in controlled air with a handling means configured to place the EUV outer pods (150) into and retrieve the EUV outer pods (150) from the EUV outer pod buffer stock (750).

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