Stocker System

Abstract

A stocker system for storing a plurality of reticles, particularly EUV reticles, comprising a plurality of storage pods (110), each configured to hold one of the reticles therein and stacked vertically one above the other to form a stack (80), each of the storage pods (110) comprising an aisle (211) having an inlet (210), an outlet (220) and a first opening (230), the inlets and outlets of adjacent aisles (211) being provided with ducts (90) extending through the stack (80) to blow purge gas, the purge gas blown through the ducts (90) returning to each storage pod (110) through its respective first opening (230).

Description

[Technical field]

[0001] The present invention relates to a storage system for storing reticles, particularly EUV reticles, a corresponding storage stocker and an apparatus for retrieving the reticles.The present invention further relates to a method for handling reticles. [Background technology]

[0002] Photolithography processes are widely used as one of the key steps in the manufacture of integrated circuits (ICs) and other semiconductor-related devices and / or structures. However, as the dimensions of features produced by such processes decrease, the importance of photolithography for the production of miniature ICs or other devices and / or structures increases.

[0003] In photolithography, a geometric pattern is transferred from a photomask (usually called a reticle) to a substrate, e.g., a semiconductor wafer, by the use of light, a photosensitive layer, and a subsequent etching step. Depending on the desired feature size of the substrate, the feature size of the reticle must be adapted as well as the wavelength of the light used to transfer the pattern, taking into account the Rayleigh criterion.

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

[0005] Any contamination of the reticle can degrade the imaging performance of the photolithography process and, in more severe cases, can require replacement of the reticle. Reticles are typically expensive, and therefore any reduction in the frequency with which they must be replaced is advantageous. Furthermore, replacing a reticle is a time-consuming process during which the photolithography process must be paused, thereby undesirably reducing its efficiency.

[0006] For EUV applications, not only particulate contamination with diameters below 10 nm is of concern, but also chemical contamination due to, for example, adsorption of volatile organic compounds.

[0007] Thus, reticles used in such EUV applications are typically stored in storage stockers, hereinafter simply referred to as stockers, or more generally as storage locations, and retrieved when required in connection with a lithography exposure apparatus. When they are used, the reticles are typically transported from such stockers to a process tool in a semiconductor manufacturing plant, commonly referred to as a fab. Typically, reticles are stored in a dual-shell container (dual-pod) with a so-called EUV outer pod (EOP) and EUV inner pod (EIP) during transport, as well as in the storage in the stocker.

[0008] Such double pods are described in further detail, for example, in US 2019 / 0214287 A1.

[0009] Since the tolerance level of particle contamination is extremely low, it is necessary to avoid friction of the reticle against the container (leading to wear and thus particle generation), as well as friction of the container's components against each other. Therefore, typical EIPs are designed to accommodate one reticle in such a way that it has only very limited possibilities for moving within it. They are also equipped with additional reticle retainers that are configured and adapted to fix the reticle inside the EIP. To prevent contamination, the EIPs are designed to allow a protective gas or a vacuum to be applied to the reticle. To that end, an orifice with a filter material is typically provided for the protective gas to enter from the EIP into the surroundings of the reticle contained in the respective EIP.

[0010] The EOP comprises an actuator adapted to bias a reticle securing means of the EIP into a retaining position, thereby securing a reticle within the EIP when the EOP is attached to the EIP, and also serves to secure two typical components of an EIP, commonly called a base plate and a cover, together to prevent wear caused by friction.

[0011] It should be understood that the EIP components can move relative to one another unless they are externally secured in place. To avoid friction-induced wear caused by such movement, the EOP traditionally provides such a securing function for the EIP while also providing protection against the ambient atmosphere, which is required, for example, during transfer between a storage location and a process tool that requires the reticle to operate.

[0012] EOPs are fairly bulky, leading to high space requirements or "footprint" for stockers that store EUV reticles. Furthermore, they are made of polymeric materials that are also prone to wear and outgassing of volatile organic compounds. Summary of the Invention

[0013] The present invention addresses these problems by providing a stocker system, a storage stocker, a method for handling reticles, a stack of reticle pods and an apparatus and method for removing a reticle pod from a storage pod according to the respective independent claims.

[0014] Advantageous embodiments and additional features are provided in the dependent claims and are further discussed in the following description.

[0015] The present invention provides a stocker system for storing a plurality of reticles, in particular EUV reticles, comprising a plurality of storage pods, each configured to hold one of said reticles therein and configured to be stacked vertically on one another to provide a stack, each of said storage pods having an inlet, an outlet and a first opening, the inlets and outlets of adjacent passages, or in other words the passages of adjacent storage pods, being provided with ducts extending through said stack, through which purge gas is transported, and arranged such that the purge gas transported through said ducts can enter the interior of each storage pod through its respective first opening.

[0016] The present invention provides a very compact and reliable storage system since multiple storage pods can be directly stacked on each other without any storage structure between them. At the same time, this direct stacking allows the formation of ducts extending through all stacked storage pods to supply purge gas to each storage pod individually. For effective purging of the interior of the storage pods, the present invention allows the storage pods to be made of suitable plastic materials since the outgassing effect can be effectively countered by the purge gas flowing through the storage pods. The storage pods can also be made of metal materials.

[0017] Advantageously, the first opening of each passage is provided with a particle filter so that only the purge gas can enter the interior of each storage pod through the first opening, whereby an individual environment can be provided for each storage pod, so that cross-contamination between different storage pods of the stack can be effectively avoided.

[0018] Each containment pod is provided with a second opening through which the purge gas can exit the interior of the containment pod, and the second openings are also preferably provided with a particle filter. Providing these second openings with particle filters further minimizes the risk of cross-contamination.

[0019] Advantageously, each storage pod is provided with at least one handling member, such as a handling flange or handle. Preferably, the handling members can be provided on all four sides of the storage pod, so that a handling robot can grasp the storage pod with the handling members without the need to rotate the storage pod, which significantly reduces the handling time. Such a handling robot is preferably provided with at least one handling element, also known as an end effector, for handling, i.e. transporting, the storage pod.

[0020] According to a preferred embodiment, each storage pod comprises a base plate and a cover, the storage pods being provided with alignment mechanisms configured and adapted to mechanically align adjacent storage pods in a stacked configuration, in particular the base plate being provided with grooves or pins and the cover being provided with pins or grooves, the grooves and pins being provided to interact with corresponding pins or grooves provided on the adjacent storage pods. Such mating grooves and pins ensure accurate and precise alignment and positioning of the storage pods of the stack. For example, adjacent storage pods stacked on top of each other can each be provided with interacting pins, often called kinematic pins in the technical field, preferably dome-shaped pins and correspondingly shaped recesses. This allows alignment and positioning of the storage pods and at the same time provides a safeguard against horizontal movements of adjacent storage pods. This is advantageous to ensure effective handling by a handling robot.

[0021] Advantageously, each storage pod is provided with a latching mechanism for fixing the base plate and the cover to each other. Such a latching mechanism may comprise a number of latches and ensures a gas-tight connection between the base plate and the cover, these components being typically made of metallic materials. In particular, such a latching mechanism prevents the base plate and the cover from moving relative to each other in a locked state, thereby preventing wear. The latching mechanism may also be configured to fix the reticle to the storage pod, which also minimizes the effects of wear and contamination.

[0022] The present invention also provides a storage stocker comprising such a stocker system and an enclosure adapted to store the stocker system. Such a storage stocker generally includes a front-end equipment module (EFEM) including at least one load port and a storage area in which the stocker system is located. The storage stocker is part of a semiconductor fab.

[0023] The storage stocker advantageously includes a fastening mechanism, e.g., a clamping mechanism or a spring mechanism, for physically fastening the individual storage pods to each other and / or to the storage body in which the stack is stored. This provides an efficient safety measure against earthquake damage to the individual storage pods or the reticles stored therein. For example, a spring mechanism including at least one spring can be provided to continuously provide a downward force acting on the top of the stack. For example, the spring can be configured to push down with a plate located above the top storage pod. The plate can be provided with a handle, e.g., shaped in a similar manner to the handling members that may be provided on the storage pods, so that the handle and plate can be lifted to access the top storage pod. The plate can be provided with alignment features (e.g., pins and / or holes) located on its underside facing the storage pods to engage with corresponding alignment features, such as holes and / or pins, on the top storage pod. Alternatively, a permanently empty storage pod in the upper position can be used instead of such a plate. The robot operates against the spring mechanism when lifting the stack. A spring mechanism comprising at least one spring may also be provided, for example, on the underside of the stack of storage pods acting against a bottom plate below the stack. Alternatively or in addition to such a spring mechanism, a cam or other type of clamping mechanism may exert a force on the top plate, the top storage pod, the bottom plate or the bottom storage pod. Such a cam or clamp is actively released when access is desired.

[0024] Such securing mechanisms can be utilized in addition to gravity effects, which also help secure stacked storage pods together.

[0025] The present invention also provides a method of handling reticles, particularly EUV reticles, comprising the steps of transporting the reticle in a transport pod between a point of use, typically a semiconductor process tool, and a storage or storage location, including a reticle stocker system as described in the present invention, or vice versa, transporting the reticle from the transport pod to a storage pod, and storing the reticle in the storage location in the storage pod. By using different pods for transport and storage, contamination effects on the reticle can be minimized, which is particularly important in connection with EUV reticles.

[0026] Preferably, the transport pod comprises at least an inner pod EIP, the storage pods being configured to hold one reticle therein and to be stacked vertically with the other storage pod to provide a stack, each storage pod having a passageway through which a purge gas can be transported, the passageway having an inlet, an outlet and a first opening, and the purge gas transported through the passageway can enter the interior of the storage pod through the first opening.

[0027] Advantageously, the transport pod comprises an inner pod EIP and an outer pod EOP. The EIP and / or EOP from which the reticles are removed and transferred to the storage pod may itself be stored in a transport pod buffer, which may be located, for example, above or near the EFEM handling robot.

[0028] The present invention allows for a reduction in the space required to store reticles while ensuring a lower level of contamination and improved damage protection than that provided by conventional systems. This is due in part to the fact that storage pods as used in the present invention do not leave the stocker system, in contrast to EIPs previously used for storage of reticles in the stocker, as well as EIPs used for transport of reticles outside the stocker. Furthermore, chemical contamination during storage from outgassing EOPs is also prevented, and mechanical damage protection is improved over storing reticles in dual pods. As mentioned, prior art EIPs are typically made of metallic materials to prevent outgassing, whereas storage pods as used in accordance with the present invention can be made of plastic materials, although using metallic materials is also advantageous.

[0029] The present invention also provides an apparatus for retrieving a reticle pod, comprising a first handling element for handling a first reticle pod and a second handling element for handling the first reticle pod, the second reticle pod being vertically disposed adjacent to one another in a stack of reticle pods, the first reticle element and the second reticle pod being horizontally independently displaceable such that the first reticle element can be lifted from the first reticle pod, the second reticle pod being configured to be vertically disposed below the first reticle pod in the stack such that the first reticle pod can be lifted from the third reticle pod, and the stack of reticle pods, the first reticle pod and the second reticle pod can be retrieved and placed in the third reticle pod.

[0030] Advantageously, the first handling element and the second handling element have a vertical distance from each other that is greater than the vertical distance of the respective handling members provided on the first and second reticle pods with which the handling elements interact to lift the second reticle pod from the first reticle pod and remove it from the third reticle pod.

[0031] Expediently, the handling members are arranged to have a fixed vertical distance between them, which simplifies the vertical arrangement of the drives of the handling members and increases their reliability.

[0032] The first handling element and the second handling element are preferably each provided with two horizontally extending arms adapted to interact with handling members provided on either side of the first reticle pod and the second reticle pod.

[0033] Advantageously, the apparatus includes a drive device configured to displace the first handling mechanism and the second handling mechanism individually in the horizontal direction and to displace the first handling mechanism and the second handling mechanism jointly in the vertical direction.

[0034] The present invention also provides a method of removing a first reticle pod from a stack of reticle pods using an apparatus as described above.

[0035] The first and second handling elements are jointly vertically displaced to horizontally position the first handling element of the second reticle pod below the first handling element of the second reticle pod, and the third reticle pod is positioned adjacent to and vertically with the first reticle pod of the stack of reticle pods, and the first and second handling elements are jointly vertically displaced, i.e. upwards, to lift the second reticle pod from the second reticle pod. The third reticle pod and the second handling element are horizontally displaced to separate it from the second reticle pod. Here, individual storage pods can be easily removed from a stack containing n storage pods with minimal displacement of the handling elements, thus providing a storage pod and a stack including n-1 storage pods that can be individually further handled.

[0036] Aspects that need to be considered when developing such an improved storage concept include the high desirability of altering the way in which reticles are provided to the photolithography process equipment, which is typically the most complex and costly part of a semiconductor production facility.

[0037] It should be noted that all method steps discussed herein may advantageously be performed in an automated manner, for example by one or more robotic components.

[0038] The present invention also provides a storage pod configured and adapted for storing reticles in a stocker, the storage pod comprising a base plate and a cover, a latch mechanism is provided for releasably holding the base plate and cover together, the storage pod comprising an alignment mechanism configured and adapted to enable mechanical alignment with adjacent storage pads when in a stacked configuration. Preferably, adjacent storage pods so aligned in the stacked configuration are provided to be essentially identical to one another.

[0039] Advantageously, the storage pod comprises a passageway having an inlet, an outlet and a first opening, the inlet and outlet being configured such that the inlets and outlets of adjacent passageways of adjacent storage pods in the stacked configuration are arranged, thereby providing a duct extending through the stacked configuration through which purge gas can be transported, and the first opening being configured and adapted such that purge gas transported through the duct can enter the interior of the storage pod through the first opening.

[0040] Thus, the present invention provides a two-part storage pod having complementary alignment features (e.g., pins and holes) on its top and bottom surfaces so that the pods can be stacked on top of each other to facilitate automated handling.

[0041] The advantageous provision of a storage pod having an alignment mechanism can also be provided for storage pods without inlets, outlets and openings for the transfer of purge gas, as described above.

[0042] Advantages and further aspects of the present invention will be further discussed with reference to the accompanying drawings. [Brief description of the drawings]

[0043] [Figure 1] FIG. 1 shows a perspective view of a preferred embodiment of two identical storage pods for use in a stocker system according to a preferred embodiment of the present invention. [Diagram 2] FIG. 2 shows a perspective view of the base plate of one of the storage pods as shown in FIG. 1 along with a reticle. [Diagram 3] FIG. 3 shows a schematic side view of a stocker system according to a preferred embodiment of the present invention. [Figure 4] FIG. 4 shows a plan view of the base plate as shown in FIG. [Diagram 5] FIG. 5 illustrates a schematic side cross-sectional view of a storage pod according to a preferred embodiment of the present invention. [Figure 6] FIG. 6 shows a schematic plan view of a preferred embodiment of a storage stocker according to the invention in which the stocker system according to the invention can be used. [Figure 7a] FIG. 7a shows a schematic diagram of a preferred embodiment of a method for removing a storage pod from a stack of storage pods. [Figure 7b] FIG. 7b shows a schematic diagram of a preferred embodiment of a method for removing a storage pod from a stack of storage pods. [Figure 7c] FIG. 7c shows a schematic diagram of a preferred embodiment of a method for removing a storage pod from a stack of storage pods. [Figure 7d] FIG. 7d shows a schematic diagram of a preferred embodiment of a method for removing a storage pod from a stack of storage pods. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0044] Due to the very stringent cleanliness requirements, EUV reticles are usually transferred between their location of use, such as a process tool, and their storage location, commonly referred to as reticle stocker or storage stocker, in a double-shell container (double-pod) with a so-called EUV outer pod (EOP) and an EUV inner pod (EIP). These EOPs have dimensions, i.e. dimensions and shapes compatible with SEMI 152 standards, to ensure safe and secure handling on standard fab transport systems, such as overhead hoist transfer (OHT), overhead shuttle (OHS), automated guided vehicles (AGV), automated guided vehicles (PGV) and rail-guided vehicles (RGV).

[0045] Previously, reticles were also stored in these dual pods in a storage stocker. Due to the large volume requirements of such storage, recent suggestions include storing the stocker's reticles solely in the EIP. This storage of the EIP requires additional means of securing the reticles in the EIP and securing the EIP components to one another.

[0046] The present invention utilizes the idea of ​​moving reticles for storage in a storage stocker from the dual-pod EIPs used for transport as described above to dedicated storage pods that have similar overall dimensions as the EIPs, but can be stacked one on top of the other in the stocker, thereby further reducing the total required storage volume of the stocker.

[0047] This general concept will now be further explained with reference to FIG. 6, which shows the main components of a storage stocker.

[0048] The storage stocker shown in FIG. 6 is generally designated 600. It comprises an equipment front end module (EFEM) 620 with two load ports 610 (one of which is shown holding an EUV double pod 611, the other of which is shown empty for purposes of illustration), an EFEM handling robot 622, and an EIP opener station 624. The storage stocker 600 further comprises a storage area 640 including a storage pod opener station 642, a storage robot 644, and a storage shelf 660, which are adapted to hold a stack of storage pods containing reticles, in particular a stocker system according to the present invention. For purposes of illustration, a storage pod 661 is shown in relation to the storage shelf 660.

[0049] The EFEM handling robot 622 and the storage robot 644 typically comprise two end effectors 622a, 622b and one end effector 644a, respectively. The end effectors are provided as gripping or handling mechanisms. The first end effector 622a of the EFEM handling robot 622 is configured to handle and move EIPs, and the second end effector 622b of the EFEM handling robot 622 is configured to handle and move bare reticles. The storage robot 644 may be provided with two end effectors configured to handle and move storage pods and reticles, respectively, or may be provided with only one end effector, for example to handle only storage pods, as shown in FIG. 6.

[0050] Typically, a double pod (EUV pod) 611 comprising an outer pod EOP and an inner pod EIP, containing a reticle to be stored in a storage stack in the storage area 640, is sent to one of the load ports 610 of the EFEM 620. At the load port 610, the outer pod EOP is opened so that the inner pod EIP, still containing the reticle to be stored, can be removed from the outer pod EOP and transferred to the EIP opener station 624 by the EFEM robot 622 using its first end effector. In an alternative embodiment not further described here, it is also possible to open the inner pod at the load port 610 and transfer the bare reticle directly to an opened storage pod provided at the storage pod opener station 642. In this alternative embodiment, it is not necessary to provide a designated EIP opener station such as the EIP opener station 624 in addition to the load port 610.

[0051] At EIP opener station 624, the inner pod EIP is opened such that the bare reticle contained in the EIP becomes accessible. At the same time, the storage robot 644 transfers a storage pod 661 using its first end effector 644a from a storage stack on the storage shelf 660 to the storage pod opener station 642. At the storage pod opener station 642, the storage pod 661 is opened. The EFEM handling robot 622 then transfers the bare reticle from the opened EIP at EIP opener station 624 to the opened storage pod at storage pod opener station 642 using its second end effector 622b.

[0052] The storage pod 661 at the storage pod opener station 642 is then closed and the storage pod 661 with the reticle therein is returned by the storage robot 644 to its storage stack on the storage shelf 660 .

[0053] To transfer reticles stored in storage pods 661 of a storage stack on storage shelf 660 to load port 610, the above steps can be performed in reverse order.

[0054] It should be noted that the storage pod opener station 642 is advantageously provided as a lock between the storage area 640 and the EFEM. Here, a clear level difference in cleanliness can be maintained in or between different sections of the storage stocker. Advantageously, the storage pod opener station 642 comprises two doors (not shown in FIG. 6), a first of which can be opened and closed towards the EFEM 620 and a second of which can be opened and closed towards the storage area 640. After the reticle is transferred to the storage pod of the storage pod opener station 642 through the first door, the second door is closed and then the first door is also closed. In this state, the storage pod opener station 642 can be purged by a purge gas system (not explicitly shown), for example to achieve a higher cleanliness level than that of the environment in the EFEM 620. This purging can be performed before and / or after the storage pod is closed with the reticle inside it.

[0055] Once this is accomplished, a second door to the hangar opens and the storage pod is transferred to a storage stack on storage shelf 660.

[0056] The storage pods as used in the present invention remain inside the stocker during normal use, i.e. for storing reticles, and not for the transport of reticles in the semiconductor fab. However, it is possible to remove the empty storage pods from the stocker for specific purposes, such as cleaning procedures. This removal of the empty storage pods from the stocker can advantageously be done via the same path that the reticles take, i.e. via the EFEM handling robot. Thus, contamination of the storage pods, especially from the fab environment, can be minimized compared to previous solutions.

[0057] The EFEM handling robot 622 can also transport empty storage pods to one of the outer load ports 610 where they can be placed in a dedicated outer pod, where they can be transported to a cleaning apparatus. Advantageously, the EFEM handling robot 622 uses here its first end effector 622a.

[0058] The EFEM advantageously comprises an AMC filtered FFU for a Class 1 mini environment, and isolation is provided between the EFEM and the fab environment, as well as between the EFEM and the storage area 640 for the storage pods.

[0059] The EFEM is typically equipped with multiple load ports, such as load port 610 as described above, for standard EUV pods according to standard SEMI E152 used for fab transport between different items of equipment. These load ports are adapted to open the EUV pod, in particular the EOP, as described above. The load ports may also be adapted to open the EIP, a variant not explicitly shown in the figures, to gain access to the bare reticle inside.

[0060] In Figure 1, two storage pods, each adapted to store a reticle in a reticle stocker, are designated 110. Each storage pod 110 includes a base plate 112 and a cover 114. Figure 1 shows the storage pods 110 in their closed state in which they normally house a reticle.

[0061] The base plate 112 and cover 114 are held together by latching mechanisms 116, of which two latches 117 on the front side of the storage pod 110 are visible in FIG. 1. Two more latches are provided on the rear side of the storage pod 110 that are not visible in FIG. 1. Typically, the latching mechanisms may be provided to define three states: a locked state in which the base plate 112 and cover 114 are securely closed while providing a protected interior; an unlocked state in which the base plate 112 and cover 114 may be separated from one another, e.g., to load or unload a reticle; and an idle state in which the latches 117 are disabled for use with other tools, e.g., for cleaning. Typically, the latches 117 remain in the idle position until actively returned to the locked or unlocked state.

[0062] The latching mechanism 116 serves to hold the base plate 112 and the cover 114 together during storage in the reticle stocker and during transport between transfer stations (e.g., storage pod opener station 624) where the reticles are transferred from the EIP of the dual pod to the storage pod 110 and vice versa. It is noted that the latching mechanism can hold the base plate and the cover together in an airtight manner to provide a separate atmosphere inside the storage pod, thus minimizing contamination from outside. Also, for example, in case of a positive gas pressure inside the reticle pod, the clamping mechanism does not need to hold the base plate and the cover together in a hermetic manner to minimize contamination inside the storage pod. This kind of transfer station is typically integrated in the reticle stocker. Advantageously, in the locked position, the latching mechanism serves to prevent any movement of the base plate 112 and the cover 114 relative to each other, thereby minimizing or avoiding any wear effects during storage of the reticle that may lead to unacceptable contamination.

[0063] The EFEM described above may be provided with a storage pod opening mechanism that may activate and deactivate the latch mechanism 116 .

[0064] The storage pod 110 includes a mechanism for securing the reticle inside the storage pod when the storage pod is in a closed position, which further minimizes potential contamination due to wear effects caused by movement of the reticle in the storage pod. Advantageously, the latch mechanism 116 is configured to secure the base plate and cover together and secure the reticle relative to the storage pod, as described above.

[0065] On both sides of the storage pod 110, handling members 120 such as handling flanges or handles are provided. Providing a handling member on each side allows a handling robot to grasp the storage pod 110 from any side without having to rotate the storage pod. In the embodiment shown, the side handling members are provided on the cover 114. It is also conceivable to provide them on the base plate 112 or, for example, on two opposite sides of the base plate and on two different opposite sides of the cover, thereby enabling or at least simplifying individual handling of the base plate or the cover by the handling robot.

[0066] The base plates and covers are advantageously provided with complementary alignment features to enable or facilitate physical or mechanical alignment of the storage pods in a stacked configuration. In the embodiment shown in FIG. 1, for example, each base plate 112 is provided with a number of grooves 130 formed on its underside. Each cover is provided with a corresponding number of pins ("kinematic pins") 132 on its upper side. Alternatively, each base plate may be provided with a number of pins and each cover with a number of corresponding grooves. The grooves 130 and pins 132 are formed and positioned to fit together such that a precise alignment of the storage pods is provided when they are stacked on top of each other. Such a precise alignment is a prerequisite for effective robotic handling by a handling robot. Advantageously, the grooves 13 are provided as elongated holes or slots. As can be seen from FIG. 1, the two pins 132 on the left side of the cover 114 interact with the left ends of the associated grooves 130, whereas the pins 132 on the right side of the cover interact with the right ends of the associated grooves 130. Here, relative movement between the base plate and the cover is effectively avoided, while the remaining parts of the grooves 130, i.e. the parts that do not interact with the respective pins, can be utilized for other purposes, such as handling purposes.

[0067] To retrieve a targeted storage pod from a stack of storage pods, the handling robot lifts the partial stack including all storage pods located above the targeted storage pod by gripping the flange 150 of the lowest storage pod in this partial stack, thus allowing easy access to the targeted storage pod 110. The individual storage pods can have a fixed or dedicated position in the stack, or can be randomly arranged. Advantageously, every storage pod is provided with an identification code, for example in the form of an RFID.

[0068] The dimensions of the containment pod 110, ie, its size and shape, are preferably fully compatible with existing automated EUV pod cleaning equipment.

[0069] In Figure 2, the base plate 112 of storage pod 110 is shown without a cover. A reticle 300 is disposed on the base plate. During normal use of storage pod 110, i.e., for storing a reticle in a stocker, the cover (not shown in Figure 2) together with base plate 112 as shown provide a protected interior for reticle 300. Reticle 300 is thus housed within the interior of storage pod 110. This interior is designated 110a in Figures 3, 4, and 5 and will be further described below.

[0070] The stocker system also provided a purge gas flow for each storage pod, which is further described below with particular reference to Figures 2-5.

[0071] 3 and 5, the base plate 112 of each storage pod is provided with an inlet 210, which flows on the one hand through a passage 211 (provided in the base plate and the corresponding cover) to an outlet 220 (marked by arrow 211a in FIG. 5) provided in the corresponding cover, and on the other hand through an opening 230 provided with a filter 235, preferably a PTFE filter, into the interior of the storage pod, thus providing a purge flow for the reticle 300, as indicated by arrow 310 in FIGS. 2, 3 and 5. The purge gas can leave the interior 111a of the storage pod 110 on the opposite side of the base plate through a purge gas opening 250 also provided with a filter 255, preferably a PTFE filter.

[0072] The general principle of this purge gas flow through the stocker system is shown in FIG. 3, while the preferred embodiment is shown in FIGS. 4 and 5, and also in FIG.

[0073] 3, this shows three storage pods 110 stacked one on top of the other to provide a stack 80. The base plates and covers of the storage pods 110 are not explicitly referenced in FIG 3. Each storage pod 110 contains a reticle 300.

[0074] 6, on a shelf plate 670 that is part of a storage shelf 660 of the storage body, and a cover plate 75 is provided on top of the stack 80. Advantageously, to stabilize the stack 80, and in particular to prevent damage caused by inadvertent agitation, e.g., caused by an earthquake, securing mechanisms, such as spring or clamp mechanisms, may be provided to secure the storage pods 110 of the stack 80 to one another and to the storage body on which it is located, e.g., the storage shelf 660 as described above, in some embodiments, the storage shelf 660 and / or the cover plate 75 include alignment features (e.g., pins and / or grooves) that are complementary to the alignment features of the storage pods located at the bottom and / or top storage pod locations of the stack 80.

[0075] 3, a spring mechanism 65 is shown diagrammatically consisting of multiple spring elements 68 disposed between a cover plate 75 and the underside of the storage shelf 662, thereby exerting a continuous downward force on the cover plate 75 and, therefore, on the stack 80. As will be readily appreciated, such a spring mechanism could also be provided below the bottommost storage pod to provide an upward force acting on the stack 80 from below.

[0076] As mentioned above, each storage pod 110 is formed with an inlet 210 (located in the base plate, not explicitly designated in FIG. 3) and an outlet 220 (located in the cover, not explicitly designated in FIG. 3). The inlets and outlets of the storage pods communicate with each other via a passageway 211 that extends through each storage pod 110. Each outlet 220 is immediately adjacent the inlet 210 of an adjacent storage pod 110. Thus, a duct 90 is formed that extends generally vertically through the entire stack 80.

[0077] Each passageway 211 also has a first opening 230 into the interior 110a of the respective storage pod 110. Each first opening is advantageously provided with a filter 235, which allows the purge gas to be transferred or blown through duct 90 into the interior 110a of each storage pod, but prevents contamination by particles present in the purge gas in duct 90, as will be further explained below. Again, this flow of purge gas into and through each storage pod 110 is labeled by arrows 310.

[0078] In all, purge gas from a purge gas source (not shown) is transported vertically through openings in the shelf plate 70 into ducts 90 formed by passages 211 (indicated by arrows 270 in FIG. 3 ) of the stacked storage pods 110. The upper ends of the ducts 90 are defined by cover plates 75, which block the flow of purge gas. This flow of purge gas through the ducts 90 and the respective storage pods 110 is effected by providing a corresponding pressure differential, for example, by use of pressurized purge gas and / or a ventilation system (both not shown).

[0079] As mentioned, a portion of this purge gas enters the interior 110a of each of the storage pods 110 through the first opening 230, thus providing an essentially horizontal flow of purge gas around the reticle 300 of each storage pod 110. At the side of the storage pod opposite the passage 211, the purge gas exits the storage pods 110 through respective second openings 250, which are also provided with particle filters 255.

[0080] By providing a common purge gas supply (pressure plenum) via duct 90 and simultaneously providing filters at first opening 230 and second opening 250, a highly effective purge gas flow can be provided individually through each storage pod 110 of stack 80. The storage pods 110 thus act as individual storage environments for the respective reticles, and cross-contamination between different storage pods 110 can be effectively avoided. Each storage pod 110 is supplied with fresh, uncontaminated purge gas at all times.

[0081] 4 and 5, with further reference to FIG 2, a preferred embodiment of the openings and passages adapted to provide purge gas flow through the individual storage pods 110 and stacks 80 is described. Note that the outline of the base plate 112 and cover 114 is depicted in dashed lines in FIG 5.

[0082] An opening 210 is formed in the underside of the first side wall of the base plate 112, indicated as 112a in Figures 2 and 4, through which the purge gas enters a passage 211. The cover 114 is provided with a corresponding passage 211, as can be seen in Figure 5. Through the passages 211 formed in the base plate 112 and the cover, the purge gas can be transported through the individual storage pods 110. In the case where several storage pods 110 are stacked on top of each other, this purge gas flow can be provided through all said storage pods 114, from the one at the bottom to the one at the top of the stack. The part of the purge gas that flows through the passage 211, and therefore through the duct 90 as described with reference to Figure 3, does not enter the interior of the respective storage pod.

[0083] At the same time, in each storage pod 110, another portion of the purge gas flow enters the interior 110a through opening 230 and includes filter 235. This portion of the purge gas provides an effective purge for reticles stored in the storage pod and exits the storage pod through opening 250, which is also provided with filter 255, as also described above with reference to FIG.

[0084] According to the embodiment as shown in Figure 3, the purge gas enters the storage pod interior 110a through a vertically extending filter 235. That is, according to the embodiments of Figures 2, 4 and 5, the initial purge gas flow therethrough is essentially horizontal, but it should be noted that the filter 235 is positioned to extend essentially horizontally such that the initial flow into the storage pod interior 110a is vertical, or has at least a vertical component, as indicated by arrow 310 in Figure 2 or arrow 310 in Figure 5.

[0085] 7a-7d show a preferred embodiment of a method for removing a storage pod from a stack of storage pods. In the illustrated example, the stack comprises six storage pods 110. For ease of reference, a first storage pod is designated 110a, a second storage pod vertically adjacent and above the first storage pod is designated 110b, and a third storage pod vertically adjacent and below the first storage pod is designated 110c. For purposes of clarity, as used herein, the terms vertical, up and down refer to the direction of gravity, with up meaning further down or below, closer to the center of the Earth, and the term horizontal refers to a direction extending perpendicular to the direction of gravity.

[0086] Each storage pod 110 is provided on either side with two horizontally extending handling members 120, e.g. handling flanges or handles, only one of which is visible for each storage pod in Figures 7a-7c.

[0087] An apparatus for removing an individual storage pod from a stack of storage pods is designated 740. Effectively, the apparatus 740 is part of the storage robot 644, as shown in Figure 6. The apparatus 740 is provided with two handling elements 742 and 744, each comprising two horizontally extending arms or grippers for engaging with respective handling members 120 on either side of the storage pod 110. Only one arm per handling element is visible in Figures 7a-7d.

[0088] The handling elements are displaceable by a drive mechanism, not shown in Figures 7a to 7d. The drive mechanism is also advantageously part of the storage robot 644, as shown in Figure 6, which is adapted to displace the handling elements 742 and 744 vertically as well as horizontally. As will be shown below, the drive mechanism is designed to move the handling elements horizontally and vertically, either simultaneously or individually. This means that for the separate horizontal movement of the handling elements 742 and 744 two separate drives are provided, while for the vertical movement of the handling elements 742 and 744 only one drive is required.

[0089] In a first step, the handling elements 742 and 744 (in the perspective of Figures 7a-7d) arranged to the right of the stock of the storage pod 110 in Figure 7a are displaced to the left, so that the handling element 742 is below the handling member 120 of the first storage pod 110a and the handling element 744 is below the handling member of the second storage pod 110b. As can be seen in Figures 7a-7d, the vertical distance between the handling elements 742 and 744 is slightly greater than that of the handling members of the first and second storage pods 110a and 110b, so that in the position shown in Figure 7b, the vertical distance between the handling element 742 and the handling member of the first storage pod 110a is slightly greater than that between the handling element 744 and the handling member of the second storage pod 110b.

[0090] This means that when the handling elements 742 and 744 move vertically upwards together, first the second storage pod 110b is lifted off the first storage pod 110a, and then the first storage pod 110a is lifted off the third storage pod 110c. As a result, the first storage pod 110a, which is no longer in contact with the adjacent storage pods 110b, 110c, can be easily removed from the stack by a horizontal movement of the handling element 742 (to the right in the perspective of FIG. 7c). A subsequent joint vertical downward movement of the handling elements 742 and 744 can place the second storage pod 110 on the third storage pod 110c, the resulting situation of which is shown in FIG. 7d. The handling element 744 can then also be moved, for example, to the right, in order to return to the position shown in FIG. 7a.

[0091] As mentioned above, the vertical displacement of the handling elements 742, 744 can advantageously be provided by a single drive, but it is also possible to provide this vertical displacement using one drive and a transmission mechanism connecting the two handling elements so that they can move vertically apart from each other, or by providing each of the two handling elements with an individually controllable vertical drive.

Claims

1. 1. A stocker system for storing a plurality of reticles, comprising a plurality of storage pods (110) each configured to hold one of the reticles therein and stacked vertically one above the other to provide a stack (80), each of the storage pods (110) comprising an aisle (211) having an inlet (210), an outlet (220) and a first opening (230), the inlets and outlets of adjacent aisles (211) being arranged such that a duct (90) is provided extending through the stack (80) through which a purge gas can be transferred, the purge gas transferred through the duct (90) being capable of entering an interior (110a) of each of the storage pods (110) through each of the first openings (230), the first openings (230) of the aisles (211) comprising a particle filter (235).

2. 2. The stocker system of claim 1, wherein each of the storage pods (110) comprises a base plate (112) and a cover (114), the entrance (210) being provided in the base plate (112) and the exit (220) being provided in the cover (114).

3. 3. The stocker system of claim 1, wherein each of the storage pods (110) is provided with a second opening (250) through which purge gas can exit the interior (110a) of the storage pod (110), and the second opening (250) is provided with a particle filter (255).

4. The stocker system according to any one of claims 1 to 3, wherein each of said storage pods (110) is provided with at least one handling member (120).

5. The stocker system of any one of claims 2, or claim 3 that relies on claim 2, or claim 4 that relies on claim 2, wherein an alignment mechanism configured and adapted to mechanically align adjacent storage pods of the stack (80) is provided, and the cover (114) is provided with pins (132) or grooves, the grooves and pins being provided for interacting with corresponding pins or grooves provided on adjacent storage pods (110).

6. The stocker system of any one of claims 2 to 5, wherein each of the storage pods (110) includes a latch mechanism (116) for securing a base plate (112) and a cover (114) together.

7. A storage stocker comprising: a stocker system according to any one of claims 1 to 6; and a storage body (660) configured to store said stocker system.

8. 8. The storage stocker of claim 7, further comprising a fastening mechanism configured to physically fasten individual storage pods to one another and / or to the storage body (660).

9. A method for handling a reticle, comprising the steps of transporting the reticle between a use location and a storage location, or vice versa, in a transport pod, transporting the reticle from the transport pod to a storage pod, or vice versa, and storing the reticle in a storage location in the storage pod.

10. 10. The method of claim 9, wherein the transport pod comprises at least an inner pod EIP, the storage pod is configured to hold / store one reticle therein and be stacked vertically one above the other with other storage pods to provide a stack, each of the storage pods comprising an inlet, an outlet, and a passageway through which purge gas can be blown out at a first opening, the purge gas blown out through the passageway being capable of entering the interior of the storage pod through the first opening.

11. An apparatus for removing a first reticle pod (110a) from a stack of reticle pods (100), comprising: a first handling element (742) for handling the first reticle pod (110a); and a second handling element (744) configured to handle a second reticle pod (110b), the second reticle pod (110b) being disposed adjacent to and vertically above the first reticle pod (110a) in the stack of reticle pods (100), allowing the second reticle pod (110b) to be lifted from the first reticle pod (110a), and the first reticle pod (110b) being lifted from the first reticle pod (110a). the first handling element (742) and the second handling element (744) are configured to be individually horizontally displaceable and individually vertically displaceable to enable a third reticle pod (110c) to be lifted from a third reticle pod (110a), a third reticle pod (110c) being positioned vertically below and adjacent to the first reticle pod (110a) in the stack of reticle pods (100), the first reticle pod (110a) can be removed from the stack of reticle pods (100) and the second reticle pod (110b) can be placed into the third reticle pod (110c).

12. 12. The apparatus of claim 11, wherein the first handling element (742) and the second handling element (744) are configured to have a first vertical distance greater than a second vertical distance of each handling member provided on the first reticle pod (110a) and the second reticle pod (110b) when the second reticle pod (110b) is stacked on the first reticle pod (110a), and the first handling element (742) and the second handling element (744) interact to lift the second reticle pod (110b) from the first reticle pod (110a) and to lift the first reticle pod (110a) from the third reticle pod (110c).

13. The apparatus of claim 12 , wherein the first vertical distance is a fixed vertical distance.

14. The apparatus of any one of claims 11 to 13, wherein the first handling element (742) and the second handling element (744) are each provided with two horizontally extending arms adapted to interact with handling members provided on either side of the first reticle pod (110a) and the second reticle pod (110b), respectively.

15. The apparatus according to any one of claims 11 to 14, comprising a drive device configured to displace the first handling element (742) and the second handling element (744) individually in a horizontal direction and to displace the first handling element (742) and the second handling element (744) together in a vertical direction.

16. A method for removing a first reticle pod (110a) from the stack of reticle pods (100) using an apparatus according to any one of claims 11 to 15.

17. The first handling element (742) and the second handling element (744) displace together in a horizontal direction to position the first handling element (742) below the handling members (120) of the first reticle pod (110a) and to position the second handling element (744) below the handling members (120) of the second reticle pod (110b), and the first handling element (742) and the second handling element (744) displace together in a vertical direction to lift the second reticle pod (110b) from the first reticle pod (110a) and to lift the first reticle pod (110a) from a third reticle pod (110c).

17. The method of claim 16, wherein the third reticle pod (110c) is positioned vertically below and adjacent to the first reticle pod (110a) in the stack of reticle pods (100), the first handling element (742) is individually displaced horizontally to remove the first reticle pod (110a) from the stack of reticle pods (100), the second handling element (744) is displaced vertically to place the second reticle pod (110b) on the third reticle pod (110c), and the second handling element (744) is displaced horizontally to separate it from the second reticle pod (110b).

18. a storage pod configured and adapted to store reticles in a stocker, the storage pod comprising a base plate (112) and a cover (114), a latch mechanism (116) provided for releasably holding said base plate (112) and said cover (114) together, said storage pod comprising an alignment mechanism configured and adapted to enable mechanical alignment with adjacent storage pods in a stacked configuration of said storage pods; The storage pod further comprises a passageway (211) having an inlet (210), an outlet (220), and a first opening (230), the inlet (210) and the outlet (220) being arranged such that the inlets and outlets of adjacent passageways (211) of adjacent storage pods in the stacked configuration provide a duct (90) extending through the stacked configuration to transport purge gas, the first opening being configured and adapted such that purge gas transported through the duct (90) can enter the interior (110a) of the storage pod through the first opening (230), the first opening (230) of the passageway (211) comprising a particle filter (235).

Images