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

Background Art

[0002] The photolithography process is 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 the features generated by such processes decrease, the importance of photolithography for the production of small 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, such as a semiconductor wafer, by using light, a photosensitive layer, and subsequent etching steps. Depending on the desired feature size of the substrate, the feature size of the reticle needs to be adapted, taking into account the Rayleigh criterion, to the wavelength of the light used for pattern transfer.

[0004] To reduce the achievable minimum feature size, the use of extreme ultraviolet (EUV) radiation has been proposed. EUV radiation 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 potentially degrade the imaging performance of the photolithography process and, in more severe cases, may require reticle replacement. Reticles are typically expensive, and thus any reduction in the frequency with which they have to be replaced is advantageous. Furthermore, reticle replacement is a time-consuming process during which the photolithography process has to be paused, which can thereby reduce its efficiency and is undesirable.

[0006] In EUV applications, contamination is not limited to particles smaller than 10 nm in size, but also includes chemical contamination, such as the adsorption of volatile organic compounds.

[0007] Therefore, reticles used for such EUV applications are typically stored in a storage stocker, which will be referred to below simply as a stocker, or more commonly as a storage location, and retrieved as needed in connection with the lithography exposure equipment. When they are used, the reticles are typically transported from such stocker to process tools in a semiconductor manufacturing plant, commonly known as a fab. Typically, reticles are stored in a double-shell container (double pod) that includes a so-called EUV outer pod (EOP) and an EUV inner pod (EIP) during transport, as well as in storage in a stocker.

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

[0009] Because the acceptable level of particulate contamination is extremely low, friction of the reticle against the container (which can lead to wear and, consequently, particle generation), as well as friction between the container's components against each other, must be avoided. Therefore, a typical EIP is designed to house one reticle in such a way that it has only very limited possibilities for movement within it. They also equip with additional reticle retainers configured and adapted to secure the reticle within the EIP. To prevent contamination, EIPs are designed to allow a protective gas or vacuum to be applied to the reticle. For this purpose, typically, an orifice with filter material is provided to allow the protective gas to enter from the EOP around the reticle contained within each EIP.

[0010] The EOP comprises an actuator adapted to bias the reticle fixing means of the EIP into a holding position, thereby fixing the reticle inside the EIP when the EOP is attached to the EIP. The EOP also functions to fix two typical components of the EIP, usually called the base plate and cover, together to prevent wear caused by friction.

[0011] It should be understood that EIP components are movable relative to each other unless they are fixed externally. To avoid friction-induced wear caused by such movement, EOPs conventionally provide such fixing functionality for EIPs while also providing protection from the ambient atmosphere, which is required, for example, during transport between a storage location requiring a reticle for operation and a process tool.

[0012] EOPs are quite bulky, leading to high space requirements or a "footprint" for the storage containers that house the EUV reticles. Furthermore, they are made from polymer materials that are also prone to wear and gas release of volatile organic compounds. [Overview of the project]

[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 reticle pods from a storage pod, each according to an independent claim.

[0014] Advantageous embodiments and additional features are provided in the dependent claims and will be discussed further 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 configured to stack vertically with respect to each other to provide a stack, each of which is configured to hold one of the reticles inside itself, each of which is provided with an inlet, an outlet and a first opening, and the inlets and outlets of adjacent passages, or in other words, passages of adjacent storage pods, are provided with ducts extending through the stack through which purge gas is transported, and the purge gas transported through the ducts is provided to enter the interior of each storage pod through its respective first opening.

[0016] The present invention provides a highly compact and reliable storage system because multiple storage pods can be directly stacked on top of each other, without any storage structures between them. Simultaneously, this direct stacking allows for the formation of ducts extending through all the stacked storage pods to individually supply purge gas to each pod. As an effective purging mechanism within the storage pods, the present invention allows the storage pods to be made of suitable plastic materials, as the purge gas flowing through the pods effectively counteracts the gas release effect. The storage pods can also be made of metal materials.

[0017] Advantageously, a particle filter is provided at the first opening of each passage so that only purge gas can enter the interior of each containment pod through the first opening. Here, individual environments can be provided for each containment pod so that cross-contamination between different containment pods in the stack can be effectively avoided.

[0018] Each containment pod is provided with a second opening through which purge gas can exit the interior of the containment pod, and the second opening is preferably also provided with a particle filter. Providing particle filters at these second openings 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 member can be provided on all four sides of the storage pod, so that the handling robot can grasp the storage pod with the handling member without requiring the storage pod to rotate. This significantly reduces handling time. Such a handling robot preferably has 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, and the storage pods are provided with an alignment mechanism configured and adapted to mechanically align adjacent storage pods in a stacked configuration, particularly grooves or pins provided in the base plate and pins or grooves provided in the cover, and the grooves and pins are provided to interact with corresponding pins or grooves provided in adjacent storage pods. Such mating grooves and pins ensure accurate and precise alignment and positioning of the stacked storage pods. For example, adjacent storage pods stacked on top of each other may be provided with interaction pins, often called motion pins in the art, preferably dome-shaped pins, and recesses of a corresponding shape, respectively. This allows for alignment and positioning of the storage pods, while simultaneously providing a safety measure against horizontal movement of adjacent storage pods. This is advantageous for ensuring effective handling by a handling robot.

[0021] Advantageously, each storage pod is provided with a latching mechanism for securing the base plate and cover to each other. Such a latching mechanism may have multiple latches and ensure a gas-tight connection between the base plate and the cover, and these components are typically made of metal. In particular, such a latching mechanism prevents the base plate and cover from moving relative to each other in a locked state, thereby preventing wear. The latching mechanism can also be configured to secure the reticle to the storage pod, thereby minimizing the effects of wear and contamination.

[0022] The present invention also provides a storage stocker comprising such a stocker system and a storage body adapted to house the stocker system. Such a storage stocker generally includes an equipment front-end module (EFEM) having 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] It is advantageous for the storage stocker to have a fastening mechanism, such as a clamping mechanism or a spring mechanism, to physically secure 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 damage to individual storage pods or reticles stored inside due to earthquakes. 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 press down on a plate positioned above the uppermost storage pod. This plate may be provided with a handle, for example, molded in a similar manner to a handling member that may be provided on the storage pod, so that the handle and plate can be lifted to access the top storage pod. The plate may be provided with an alignment shape configuration (e.g., a pin and / or hole) located on its underside facing the storage pod to engage with the corresponding alignment shape configuration, such as a hole and / or pin, on the uppermost storage pod. Alternatively, a permanently empty storage pod in the upper position can be used instead of such a plate. When the robot lifts the stack, it acts against the spring mechanism. A spring mechanism with at least one spring may be provided on the underside of the stack, for example, acting against the bottom plate beneath the stack of storage pods. Instead of, or in addition to, such a spring mechanism, a cam or other type of clamping mechanism may exert force on the top plate, the uppermost storage pod, the bottom plate, or the lowermost storage pod. Such a cam or clamp is actively released when access is desired.

[0024] Such a fixing mechanism can be used in addition to the effect of gravity, and it also helps to secure stacked storage pods to each other.

[0025] Furthermore, the present invention provides a method for handling reticles, particularly EUV reticles, comprising the following steps: transporting the reticle in a transport pod between a place of use, typically a semiconductor process tool, and a storage or storage location, including the reticle stocker system 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 of the storage pod. By using different pods for transport and storage, the contamination effect on the reticle can be minimized, which is particularly important in relation to EUV reticles.

[0026] Preferably, the transport pod comprises at least an internal pod EIP, and the storage pod is configured to hold one reticle inside and stack vertically with the other storage pod to provide a stack, with each storage pod comprising a passage through which purge gas can be transported, having an inlet, an outlet and a first opening, and the purge gas transported through the passage 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, once the reticle has been removed and transported to the storage pod, can themselves be stored in a transport pod buffer, which may be located above or near the EFEM handling robot, for example.

[0028] The present invention enables 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 the EIPs that were previously used for storing reticles in the stocker and the EIPs that were used for transferring reticles outside the stocker. Further, chemical contamination during storage from gas emission EOPs is also prevented, and mechanical damage protection is improved over storing the reticle in a double pod. As mentioned, the prior art EIPs are typically made of metal materials to prevent gas emission, while storage pods as used in accordance with the present invention can be made of plastic materials, although it can also be advantageous to use metal materials.

[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 a first reticle pod, the second reticle pod being vertically disposed adjacent to each other in a stack of reticle pods, the first reticle element and the second reticle pod being individually displaceable horizontally so as to be lifted from the first reticle pod, the first reticle pod being formed to be lifted from a third reticle pod and the second reticle pod being vertically disposed under the first reticle pod of the stack. It is arranged in a third reticle pod capable of retrieving a stack of reticle pods, a first reticle pod, and a second 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 where the handling elements interact, in order to lift the second reticle pod from the first reticle pod and remove it from the third reticle pod.

[0031] For convenience, the vertical distance between handling members is fixed. This simplifies the vertical configuration of the drive unit for the handling members, leading to improved reliability.

[0032] The first handling element and the second handling element are preferably provided with two horizontally extending arms that interact with the handling members provided on both sides of the first and second reticle pods.

[0033] Advantageously, the apparatus includes a drive unit configured to displace the first and second handling mechanisms individually in the horizontal direction and to displace the first and second handling mechanisms collectively in the vertical direction.

[0034] Furthermore, the present invention provides a method for removing a first reticle pod from a stack of reticle pods using the apparatus described above.

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

[0036] Aspects that need to be considered when developing such improved storage concepts include the fact that it is highly undesirable to change the way the reticle is supplied to the photolithography process equipment, which is usually the most complex and costly part of semiconductor production equipment.

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

[0038] The present invention also provides a storage pod comprising a base plate and a cover, configured and adapted for storing a reticle in a stocker, a latch mechanism for holding the base plate and cover together in a releaseable manner, and the storage pod comprising an alignment mechanism configured and adapted to allow mechanical alignment with adjacent storage pads in the case of a stacked configuration. Preferably, adjacent storage pods thus aligned in a stacked configuration are provided to be essentially identical to one another.

[0039] Advantageously, the containment pod comprises a passage having an inlet, an outlet, and a first opening, the inlet and outlet being located adjacent to the inlet and outlet of adjacent passages of adjacent containment pods in a stacked configuration, thereby providing a duct extending through the stacked configuration through which purge gas can be transported, and the first opening being configured and adapted so that the purge gas transported through the duct can enter the interior of the containment pod through the first opening.

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

[0041] The advantage of a containment pod with an alignment mechanism can also be provided for a containment pod without inlets, outlets, and openings for the transfer of purge gas, as described above.

[0042] The advantages and further embodiments of the present invention will be discussed further with reference to the accompanying drawings. [Brief explanation of the drawing]

[0043] [Figure 1] Figure 1 shows a perspective view of a preferred embodiment of two identical storage pods for use in a storage system according to a preferred embodiment of the present invention. [Figure 2] Figure 2 shows a perspective view of one of the base plates of a storage pod, as shown in Figure 1, along with the reticle. [Figure 3] Figure 3 shows a schematic side view of a storage system according to a preferred embodiment of the present invention. [Figure 4] Figure 4 shows a plan view of the base plate as shown in Figure 2. [Figure 5] Figure 5 shows a schematic side cross-sectional view of a storage pod according to a preferred embodiment of the present invention. [Figure 6] Figure 6 shows a schematic plan view of a preferred embodiment of a storage stocker according to the present invention, which can use the stocker system according to the present invention. [Figure 7a] Figure 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] Figure 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] Figure 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] Figure 7d shows a schematic diagram of a preferred embodiment of a method for removing a storage pod from a stack of storage pods. [Modes for carrying out the invention]

[0044] Due to extremely stringent cleanliness requirements, EUV reticles are typically transported between their place of use, such as process tools, and a storage location commonly referred to as a reticle stocker or storage stocker, which is a double-shell container (double pod) containing so-called EUV outer pods (EOPs) and EUV inner pods (EIPs). These EOPs have dimensions, i.e., dimensions and shapes compatible with SEMI 152 standards, to ensure safe and reliable handling on standard fab transport systems, such as overhead hoist transport (OHT), overhead shuttle (OHS), automated guided vehicles (AGVs), automated guided vehicles (PGVs), and rail guided vehicles (RGVs).

[0045] Previously, the reticle was also stored in these dual pods of the storage stocker. Due to the large volume requirements of such storage, recent suggestions include storing the stocker's reticle only in the EIP. This storage of the EIP requires additional means to secure the EIP's reticle and also to secure the EIP components to each other.

[0046] The present invention utilizes the idea of ​​transferring the reticle for storage in a storage stocker from the double-pod EIP used for transport as described above to a dedicated storage pod. This dedicated storage pod has similar overall dimensions to the EIP, but in the stocker one can be stacked directly on top of the other, thereby further reducing the total storage volume required by the stocker.

[0047] Here, we will further explain this general concept by referring to Figure 6, which shows the main components of the storage stocker.

[0048] The storage stocker shown in Figure 6 is generally shown as 600. It comprises an equipment front-end module (EFEM) 620 having two load ports 610 (one of which is shown to hold an EUV dual pod 611, and the other of which is shown as empty for illustrative purposes), an EFEM handling robot 622, and an EIP opener station 624. The storage stocker 600 further includes a storage area 640, which includes a storage pod opener station 642, a storage robot 644, and storage shelves 660, which are configured to hold a reticle, in particular a stack of storage pods including the stocker system according to the present invention. For illustrative purposes, 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 the EIP, and the second end effector 622b of the EFEM handling robot 622 is configured to handle and move the bare reticle. The storage robot 644 may also have two end effectors configured to handle and move the storage pod and the reticle, respectively, or it may have only one end effector to handle only the storage pod, for example, as shown in Figure 6.

[0050] Typically, a dual 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 storage area 640, is delivered to one of the load ports 610 of the EFEM 620. At load port 610, the outer pod EOP is opened, and as a result, the inner pod EIP, still containing the reticle to be stored, is removed from the outer pod EOP and can be transported by the EFEM robot 622 to the EIP opener station 624 using its first end effector. In alternative embodiments not further described here, the inner pod can also be opened at load port 610, and the bare reticle can be transported directly to an open storage pod provided at storage pod opener station 642. In this alternative embodiment, there is no need to provide a designated EIP opener station such as EIP opener station 624 in addition to load port 610.

[0051] At the EIP opener station 624, the internal pod EIP is opened so that the bare reticle contained within the EIP is accessible. Simultaneously, the storage robot 644 uses its first end effector 644a to transfer the storage pod 661 from the storage stack of the storage rack 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 uses its second end effector 622b to transfer the bare reticle from the EIP opened at the EIP opener station 624 to the opened storage pod at the storage pod opener station 642.

[0052] Next, the storage pod 661 of the storage pod opener station 642 is closed, and the storage pod 661, which has a reticle inside, is returned to the storage stack of the storage rack 660 by the storage robot 644.

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

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

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

[0056] The storage pods used in this invention remain inside the stocker during normal use, i.e., not used for transporting reticles in the semiconductor fab, but for storing reticles. However, it is possible to remove empty storage pods from the stocker for specific purposes, such as cleaning procedures. This removal of empty storage pods from the stocker can be advantageously carried out via the same path taken by the reticles, i.e., via an EFEM handling robot. Thus, contamination of the storage pods, particularly 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 external load ports 610, where they can be placed in a dedicated external pod, which can then be transported to the washing device. Advantageously, the EFEM handling robot 622 uses its first end effector 622a here.

[0058] The EFEM advantageously features an AMC-filtered FFU for a Class 1 mini-environment, providing separation between the EFEM and the fab environment, as well as between the EFEM and the containment area 640 for the containment pod.

[0059] The EFEM typically features multiple load ports, such as the load port 610 described above, for standard EUV pods following standard SEMI E152, which are used for transferring items between different parts of the apparatus. These load ports are adapted to open the EUV pod, particularly the EOP, as described above. The load ports may also be adapted to open the EIP, a variation not explicitly shown in the figure, to gain access to the bare reticle inside.

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

[0061] The base plate 112 and cover 114 are held together by a latch mechanism 116, of which two latches 117 located on the front side of the storage pod 110 are visible in Figure 1. Two more latches are located on the rear side of the storage pod 110, which are not visible in Figure 1. Typically, the latch mechanism may be provided to define three states: a locked state in which the base plate 112 and cover 114 are tightly closed, providing a protected interior between them; an unlocked state in which the base plate 112 and cover 114 can be separated from each other, for example, to load or remove a reticle; and an idle state in which the latches 117 are rendered unusable, for example, for use with other tools for cleaning. Typically, the latches 117 remain in the idle position until they are actively returned to the locked or unlocked state.

[0062] The latch mechanism 116 serves to hold the base plate 112 and cover 114 together while the reticle is stored in the reticle stocker and during transport to and from a transport station (e.g., a storage pod opener station 624) where the reticle is transferred from the EIP of the dual pod to the storage pod 110 or vice versa. It should be noted that the latch mechanism can hold the base plate and cover together in an airtight manner to provide a separate atmosphere inside the storage pod, thus minimizing contamination from the outside. Also, for example, in the case of positive gas pressure inside the reticle pod, the clamp mechanism does not need to hold the base plate and cover together in a sealed manner to minimize contamination inside the storage pod. This type of transport station is typically integrated into the reticle stocker. Advantageously, in the locked position, the latch mechanism works to prevent any movement of the base plate 112 and cover 114 relative to each other, thereby minimizing or avoiding any abrasion effects during reticle storage that could lead to unacceptable contamination.

[0063] The EFEM described above is provided with a storage pod release mechanism, which can 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 the closed position. This mechanism further minimizes potential contamination due to abrasion caused by the movement of the reticle within the storage pod. Advantageously, the latch mechanism 116 is configured, as described above, to secure the base plate and the cover to each other and to secure the reticle to the storage pod.

[0065] Handling members 120, such as handling flanges and handles, are provided on both sides of the storage pod 110. By providing handling members on each side, a handling robot can grasp the storage pod 110 from any side without having to rotate the storage pod. In the illustrated embodiment, the side handling members are provided on the cover 114. These could also be provided on the base plate 112, or, for example, on two opposite sides of the base plate and two different opposite sides of the cover, thereby enabling, or at least simplifying, individual handling of the base plate or cover by the handling robot.

[0066] The base plates and covers are advantageously provided with complementary alignment mechanisms to enable or facilitate the physical or mechanical alignment of the storage pods in a stacked configuration. In the embodiment shown in Figure 1, for example, each base plate 112 has a plurality of grooves 130 formed on its underside. Each cover has a plurality of corresponding pins ("movement pins") 132 on its upper side. Alternatively, each base plate may have a plurality of pins and each cover may have a plurality of corresponding grooves. The grooves 130 and pins 132 are formed and positioned to interlock with each other so that precise alignment of the storage pods is provided when they are stacked on top of each other. Such 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 Figure 1, the two left-side pins 132 of the cover 114 interact with the left end of the associated groove 130, while the right-side pins 132 of the cover interact with the right end of the associated groove 130. Here, relative movement between the base plate and the cover is effectively avoided, while the remaining portion of the groove 130, i.e., the portion that does not interact with each pin, can be used for other purposes, such as handling purposes.

[0067] To retrieve a targeted storage pod from a stack of storage pods, the handling robot lifts a partial stack, including all storage pods positioned above the targeted storage pod, by grasping the flange 150 of the lowest storage pod in this partial stack, thereby allowing easy access to the targeted storage pod 110. Each individual storage pod may have a fixed or dedicated position in the stack, or it may be randomly arranged. Advantageously, each storage pod may be provided with an identification code, for example, in the form of RFID.

[0068] The dimensions of the storage pod 110, i.e., its size and shape, are preferably such that they are perfectly compatible with existing fully automated EUV pod cleaning equipment.

[0069] In Figure 2, the base plate 112 of the storage pod 110 is shown without a cover. The reticle 300 is positioned on the base plate. During normal use of the storage pod 110, i.e., to store the reticle in the stocker, the cover (not shown in Figure 2), along with the base plate 112, provides a protected interior for the reticle 300, as shown. Thus, the reticle 300 is housed inside the storage pod 110. This interior is shown as 110a in Figures 3, 4, and 5 and will be described further below.

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

[0071] Referring particularly to Figures 3 and 5, each containment pod's base plate 112 is provided with an inlet 210, through which, on one hand, gas flows through a passage 211 (provided in the base plate and the corresponding cover) to an outlet 220 (indicated by arrow 211a in Figure 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 containment pod, thus providing a purge flow for the reticle 300, as indicated by arrow 310 in Figures 2, 3 and 5. The purge gas can exit the interior 111a of the containment pod 111 on the opposite side of the base plate through a purge gas opening 250, also equipped with a filter 255, preferably a PTFE filter.

[0072] The general principle of this purge gas flow through the stocker system is shown in Figure 3, but preferred embodiments are shown in Figures 4 and 5, and also in Figure 2.

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

[0074] The stack 80 is positioned on a shelf plate 670, which is part of the storage shelf 660 of the storage unit, as described above in relation to Figure 6, and a cover plate 75 is provided on top of the stack 80. Advantageously, to stabilize the stack 80, in particular to prevent damage caused by inadvertent agitation, for example, caused by an earthquake, a fixing mechanism such as a spring mechanism or a clamp mechanism may be provided to fix the storage pods 110 of the stack 80 to each other, and to fix the stack 80 as a whole to the storage unit, for example, the storage shelf 660 on which it is positioned, as described above. In some embodiments, the storage shelf 660 and / or the cover plate 75 include a complementary alignment mechanism (e.g., pins and / or grooves) to the alignment mechanism of the storage pods located at the bottom and / or top storage pod positions of the stack 80.

[0075] In the embodiment shown in Figure 3, a spring mechanism 65 consisting of a number of spring elements 68 positioned between the cover plate 75 and the underside of the storage rack 662 is schematically shown, so that a continuous downward force acts on the cover plate 75 and therefore on the stack 80. As can be easily understood, such a spring mechanism can also be provided below the lowest storage pod to provide an upward force acting on the stack 80 from below.

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

[0077] Furthermore, each passage 211 is provided with a first opening 230 inside the respective containment pod 110a. It is advantageous to provide a filter 235 in each first opening, which allows purge gas to enter the interior 110a of each containment pod by being transported or blown through the duct 90, but prevents contamination by particles present in the purge gas in the duct 90, as will be explained further below. In this case as well, the flow of this purge gas to and through each containment pod 110 is indicated by arrows 310.

[0078] In all cases, purge gas from a purge gas supply source (not shown) is transported vertically through an opening in the shelf plate 70 into a duct 90 formed by a passage 211 (indicated by arrow 270 in Figure 3) in the stacked storage pods 110. The upper end of the duct 90 is defined by a cover plate 75, which blocks the flow of purge gas. This flow of purge gas through the duct 90 and each storage pod 110 is brought about by providing a corresponding pressure difference, for example by using a pressurized purge gas and / or ventilation system (neither shown).

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

[0080] By providing a common purge gas supply source (pressure plenum) via duct 90, and simultaneously by providing filters at the first opening 230 and the second opening 250, an effective purge gas flow can be individually provided through each containment pod 110 of the stack 80. Each containment pod 110 then acts as an individual containment environment for its respective reticle, and cross-contamination between different containment pods 110 can be effectively avoided. Each containment pod 110 is supplied with fresh, uncontaminated purge gas at all times.

[0081] Referring here to Figures 4 and 5, and further to Figure 2, preferred embodiments of openings and passages adapted to provide purge gas flow through individual containment pods 110 and stacks 80 are described. Note that the contours of the base plate 112 and cover 114 are shown by dashed lines in Figure 5.

[0082] An opening 210 is formed on the lower side of the first side wall of the base plate 112, indicated as 112a in Figures 2 and 4, through which the purge gas enters the passage 211. The cover 114 is provided with a corresponding passage 211, as seen in Figure 5. The purge gas can be transported through the individual containment pods 110 through the passages 211 formed in the base plate 112 and the cover. When multiple containment pods 110 are stacked on top of each other, this purge gas flow can be supplied through all of the containment pods 114, from the bottom one to the top one in the stack. No portion of the purge gas that flows through the passage 211 and therefore through the duct 90 as described with reference to Figure 3 enters the interior of any of the containment pods.

[0083] Simultaneously, in each containment pod 110, another portion of the purge gas flow enters the interior 110a through an opening 230 and is equipped with a filter 235. This portion of the purge gas provides effective purging of the reticle contained within the containment pod and exits the containment pod through an opening 250, which is also equipped with a filter 255, as described above with reference to Figure 3.

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

[0085] Figures 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, the first storage pod is denoted as 110a, the second storage pod perpendicularly adjacent to and above the first storage pod is denoted as 110b, and the third storage pod perpendicularly adjacent to and below the first storage pod is denoted as 110c. For the purposes of clarification, as used herein, the terms vertical and up and down refer to the direction of gravity, the meaning of up means further away, below or below, closer to the center of the Earth, and the term horizontal refers to a direction perpendicular to the direction of gravity.

[0086] Each storage pod 110 is provided with two horizontally extending handling members 120, such as handling flanges or handles, on both sides, with only one of them visible for each storage pod in Figures 7a to 7c.

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

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

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

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

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

Claims

1. A stocker system for storing multiple reticles, comprising a plurality of storage pods (110) each configured to hold one of the reticles inside, and stacking one vertically above the other to provide a stack (80), each of the storage pods (110) comprising a passage (211) having an inlet (210), an outlet (220), and a first opening (230), the inlet and outlet of adjacent passages (211) being arranged to provide a duct (90) extending through the stack (80), through which a purge gas can be transported, the purge gas transported through the duct (90) can enter the interior (110a) of each of the storage pods (110) through the respective first opening (230), and the first opening (230) of the passage (211) comprising a particle filter (235).

2. The storage system according to claim 1, wherein each of the storage pods (110) comprises a base plate (112) and a cover (114), the inlet (210) is provided on the base plate (112), and the outlet (220) is provided on the cover (114).

3. The storage system according to claim 1 or 2, 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 storage system according to any one of claims 1 to 3, wherein each of the storage pods (110) is provided with at least one handling member (120).

5. A stocker system according to claim 2, or claim 3 relating to claim 2, or claim 4 relating to claim 2, comprising an alignment mechanism configured and adapted to mechanically align adjacent storage pods of the stack (80), wherein the cover (114) is provided with pins (132) or grooves, the grooves and pins being provided to interact with corresponding pins or grooves provided on adjacent storage pods (110).

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

7. A storage stocker comprising a stocker system according to any one of claims 1 to 6, and a storage body (660) configured to house the stocker system.

8. The storage stocker according to claim 7, further comprising a fixing mechanism configured to physically fix the individual storage pods to each other and / or to the storage body (660).

9. A method for handling a reticle, comprising: a step of transporting the reticle in a transport pod between a place of use and a place of storage, or vice versa; a step of transporting the reticle from the transport pod to a storage pod, or vice versa; and a step of storing the reticle in a storage location in the storage pod. The transfer pod comprises at least an internal pod EIP, the storage pod is configured to hold / store one reticle inside and to provide a stack, with other storage pods, one stacked vertically on top of the other, each of the storage pods comprises an inlet, an outlet, and a passage through which purge gas can be blown out at a first opening, the purge gas blown out through the passage can enter the interior of the storage pod through the first opening, the method.

10. A device 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 for handling a second reticle pod (110b), wherein the second reticle pod (110b) is positioned vertically above and adjacent to the first reticle pod (110a) in the stack of reticle pods (100), enabling the second reticle pod (110b) to be lifted away from the first reticle pod (110a). A device wherein the first handling element (742) and the second handling element (744) are configured to be individually displaceable horizontally and individually displaceable vertically, so that 0a) can be lifted from the third reticle pod (110c), the third reticle pod (110c) is positioned vertically below adjacent to the first reticle pod (110a) in the stack of the reticle pods (100), the first reticle pod (110a) can be removed from the stack of the reticle pods (100), and the second reticle pod (110b) can be placed in the third reticle pod (110c).

11. The apparatus according to claim 10, wherein the first handling element (742) and the second handling element (744) are configured to have a first vertical distance greater than the second vertical distance between the respective handling members 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 lift the first reticle pod (110a) from the third reticle pod (110c).

12. The apparatus according to claim 11, wherein the first vertical distance is a fixed vertical distance.

13. The apparatus according to any one of claims 10 to 12, wherein the first handling element (742) and the second handling element (744) are each provided with two arms that are adapted to interact with handling members provided on both sides of the first reticle pod (110a) and the second reticle pod (110b) and extend horizontally.

14. The apparatus according to any one of claims 10 to 13, comprising a drive device configured to individually displace the first handling element (742) and the second handling element (744) in the horizontal direction, and to displace the first handling element (742) and the second handling element (744) together in the vertical direction.

15. A method for removing a first reticle pod (110a) from the stack of the reticle pods (100) using the apparatus described in any one of claims 10 to 14.

16. In order to position the first handling element (742) below the handling member (120) of the first reticle pod (110a) and the second handling element (744) below the handling member (120) of the second reticle pod (110b), the first handling element (742) and the second handling element (744) are displaced together horizontally, and in order to lift the second reticle pod (110b) from the first reticle pod (110a) and lift the first reticle pod (110a) from the third reticle pod (110c), vertical The method according to claim 15, wherein the third reticle pod (110c) is positioned vertically downward adjacent to the first reticle pod (110a) in the stack of the reticle pods (100), the first handling element (742) is displaced horizontally individually to remove the first reticle pod (110a) from the stack of the reticle pods (100), the second handling element (744) is displaced vertically to position the second reticle pod (110b) on the third reticle pod (110c), and the second handling element (744) is displaced horizontally to separate from the second reticle pod (110b).

17. A storage pod configured and adapted to store a reticle in a stocker, comprising a base plate (112) and a cover (114), wherein a latch mechanism (116) is provided to hold the base plate (112) and the cover (114) in a manner that allows them to be released from each other, and the storage pod comprises an alignment mechanism configured and adapted to allow mechanical alignment with adjacent storage pods in a stacked configuration of the storage pods, Furthermore, the containment pod comprises a passage (211) having an inlet (210), an outlet (220), and a first opening (230), wherein the inlet (210) and the outlet (220) are arranged such that the inlets and outlets of adjacent passages (211) of adjacent containment pods in a stacked configuration provide a duct (90) extending through the stacked configuration to transport purge gas, the first opening is configured and adapted so that the purge gas transported through the duct (90) can enter the interior (110a) of the containment pod through the first opening (230), and the first opening (230) of the passage (211) comprises a particle filter (235).

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