WO2001081203A1 - Pod for carrying reticle cassette - Google Patents

Pod for carrying reticle cassette Download PDF

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Publication number
WO2001081203A1
WO2001081203A1 PCT/US2000/011101 US0011101W WO0181203A1 WO 2001081203 A1 WO2001081203 A1 WO 2001081203A1 US 0011101 W US0011101 W US 0011101W WO 0181203 A1 WO0181203 A1 WO 0181203A1
Authority
WO
WIPO (PCT)
Prior art keywords
base
plate
cassette
locking pin
locking
Prior art date
Application number
PCT/US2000/011101
Other languages
French (fr)
Inventor
Robert K. Lindsley
Thomas Kielbaso
Sudhir Jain
Kathy Bishop
Joseph Durben
Chakrayud Piboontum
Original Assignee
Microtome Precision, Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Microtome Precision, Inc. filed Critical Microtome Precision, Inc.
Priority to PCT/US2000/011101 priority Critical patent/WO2001081203A1/en
Publication of WO2001081203A1 publication Critical patent/WO2001081203A1/en

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Classifications

    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H01L21/00Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/67Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere
    • H01L21/673Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere using specially adapted carriers or holders; Fixing the workpieces on such carriers or holders
    • H01L21/6735Closed carriers
    • H01L21/67373Closed carriers characterised by locking systems
    • GPHYSICS
    • G03PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03FPHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F1/00Originals for photomechanical production of textured or patterned surfaces, e.g., masks, photo-masks, reticles; Mask blanks or pellicles therefor; Containers specially adapted therefor; Preparation thereof
    • G03F1/66Containers specially adapted for masks, mask blanks or pellicles; Preparation thereof
    • GPHYSICS
    • G03PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03FPHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/70Exposure apparatus for microlithography
    • G03F7/70691Handling of masks or wafers
    • G03F7/70733Handling masks and workpieces, e.g. exchange of workpiece or mask, transport of workpiece or mask
    • G03F7/70741Handling masks outside exposure position, e.g. reticle libraries
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H01L21/00Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/67Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere
    • H01L21/673Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere using specially adapted carriers or holders; Fixing the workpieces on such carriers or holders
    • H01L21/6735Closed carriers
    • H01L21/67379Closed carriers characterised by coupling elements, kinematic members, handles or elements to be externally gripped

Abstract

A reticle cassette carrying pod (10) has a top plate (16), base (30), side walls (20-22), and corner posts (26-29) removably attached in sealed engagement to define a cassette receiving chamber (32). A bottom plate (14) attaches to the cassette (74) within a receiving cavity (48) in base (30) to make the cassette receiving chamber (32) substantially airtight. Locking mechanisms (56) in the base have sliding members (58) to engage slots (60) in the bottom plate (14). Retaining members (76) are attached to a pair of sliding members (58) to constrain movement of articles (63) contained in the cassette (74) when the cassette (74) is within the receiving chamber (32) and the locking mechanisms (56) engage the slots (60) in the bottom plate (14).

Description

POD FOR CARRYING RETICLE CASSETTE

BACKGROUND OF THE INVENTION

1. FIELD OF THE INVENTION

This invention relates to improvements in pod structures for carrying cassettes of the type used to carry items, such as photolithographic reticles, or the like, used in semiconductor integrated circuit manufacturing processes.

2. RELEVANT BACKGROUND

In the performance of semiconductor manufacturing processes, as integrated circuit feature sizes decrease, it becomes more and more important to maintain the cleanliness of the reticles and other photolithographic tools that are used in the production of the semiconductor devices. For example, as feature sizes decrease to below 0.5 microns, even small dust particles that may land on the reticles that are used in the formation of the semiconductor features may cause some of the features to be miss-formed or not formed at all. This, of course reduces the yield of the semiconductor process, and, therefor, increases the expense of the process.

To reduce the particulate matter to which the parts used in the manufacturing process may be exposed, a system has been proposed, and is in widespread use, in which the parts are loaded into a cassette, which, in turn, is carried inside a transport container, or pod. Thus, for example, semiconductor wafers or reticles used in the fabrication process are loaded into a cassette, which is moved from place to place' in an air-tight pod. Standard dimensions for the pods have been proposed, one standard being the "Standard Mechanical Interface for Cassette Transfer" standard, commonly known as the SMIF standard. Typically, the reticles or semiconductor wafers are loaded into the cassette, which has an open side and receiving slots to receive the reticles or wafers. With respect particularly to reticle containing cassettes, each cassette contains, for example, a set of reticles used in a particular semiconductor fabrication process, or portion thereof. The reticles may contain the masks or mask sets necessary for the photolithographic portion of the process. When the cassette containing the reticles is loaded into the transport device, or pod, steps must be taken to ensure that the reticles remain in place in the cassette, and, moreover, that the relative movement between the reticles and the cassette is maintained at a minium. If the reticles were allowed to slide slightly during transport, the friction between the reticle and the rails or other support structures in the cassette may produce particulates that may contaminate the atmosphere within the pod, and may result in lower yields in the subsequent semiconductor manufacturing processes.

In order to maintain the relative positions of the reticles and the cassette, a retaining assembly is generally provided. The retaining assembly typically is suspended from the top or side of the pod to which the open side of the cassette faces, and operates to move a retaining member into contact with the reticles in the direction of the cassette. The retaining mechanism is held in place with an assembly that includes angularly disposed arms that have slots to engage locating pins carried by the pod. As the cassette is moved to the interior of the pod, the base or other portion on which the cassette is carried engages a bottom portion of the retaining mechanism, thereby moving it upwardly, and, due to the angular orientation of the support arms, into contact with the reticles contained within the cassette.

At least three problems exist in such a retaining mechanism. First, due to the sliding action of the angular arms on the pins, the friction between these parts may cause the generation of undesirable particulates. Secondly, as the face of the retaining member comes into contact with the edges of the reticles contained in the cassette, a sliding action between the reticles and the retaining member occurs, again, presenting the possibility of undesirable particulate generation. Thirdly, the contact point between the retaining mechanism and the surface that engages it to move into the reticles also has a sliding mechanism that gives rise to the possibility of undesirable particulate generation.

Another problem that occurs in previous pod designs is in the locking mechanisms that are provided between the top and bottom portions of the pod. (Typically, the cassette is mounted to the bottom portion that is moved to a chamber defined by the top portion of the pod to provide the air-tight chamber in which the cassette and its contents are maintained. ) It should be appreciated that a reticle set that may be used in a portion' of a semiconductor fabrication process may be valued at several thousand, or even tens of thousands, of dollars due to the intricacies of the reticles and the labor required in producing them. If the base of the pod on which the reticle cassette is carried becomes inadvertently or unexpectedly detached from the top portion of the pod during transport, a possibility exists that the reticles contained in the cassette may fall from the cassette or otherwise be subjected to breakage, which would be disastrous. Nevertheless, in the past, the locking mechanisms that have been provide between the top and bottom pod portions have been of uncertain integrity, and, moreover, ordinarily do not provide a visual indication that the lock is securely in place before the pod is lifted by an operator for transport from one location to another. As a consequence, as a matter of caution, operators frequently carry pods from one location to another with both hands, one to lift the weight of the pod by a handle, usually on the top portion of the pod, the other to support the bottom portion to which the reticle cassette is mounted.

Additionally, in the use of the pod, it is placed onto the required' processing equipment in such a way that pins on the processing equipment can engage holes or slots in the locking mechanism parts to automatically unlock the locking mechanism parts to enable the base portion of the pod to be removed and loaded into a processing chamber for robotic or other automatic semiconductor processing. However, generally no visual indicators have been provided to assure that the pod has been properly placed on the pod before the manufacturing processes are begun. This is disadvantageous in that when the process is begun, if the pod is improperly placed on the processing equipment, the integrity of the clean environment may be lost, which can be time consuming and expensive to restore.

Finally, in the past, many portions of the pods used have been molded from single sheets of plastic. As a consequence, when the pod, or portion thereof, became damaged or contaminated, the container became unusable, and often had to be entirely replaced. To partially address this problem, some transport containers have included interior liners, so that if the interior becomes contaminated, the interior liner could be replaced. This, however, only partially addressed the problem. For example, if the top portion of the pod became damaged, the entire pod top needed to be replaced. As a result, compromises have been made to reduce the cost and quality of the materials used in the construction of the pod so that replacement of the entire pod would not be prohibitively expensive. However, the reduction in quality of materials resulted in difficulties in properly maintaining the integrity of the pod, which resulted a requirement for more frequent pod replacement . SUMMARY OF THE INVENTION

In light of the above, it is therefor, an object of the invention to provide an improved pod for use in carrying a cassette of the type used to hold semiconductor processing recitals, or the like, or semiconductor wafers, for use with automated semiconductor processing equipment.

It is another object of the invention to provide a pod of the type described that has replaceable parts to enable the pod to be easily and economically repaired and recertified in the event that it becomes damaged or contaminated in use.

It is another object of the invention to provide a retaining mechanism for use in a pod of the type described that securely engages the items contained in cassette within the interior of the pod, and which does not have parts that have substantial frictional movement in operation, thereby minimizing the potential of particulate generation within the pod.

It is another Object of the invention to provide a retaining mechanism of" the type described that automatically is engagable or releasable by the operation of the retaining locking mechanisms of the top and bottom portions of the pod, for example, by operation of the automatic semiconductor processing equipment on which the pod may be emplaced.

It is yet another object of the invention to provide a locking assembly that has positive locking and unlocking preventing mechanisms to assure that the locking assembly does not inadvertently allow the pod parts to disconnect.

It is another object of the invention to provide a locking assembly for use with a pod of the type described that provides a positive visual indication that the locking mechanism is in place to prevent inadvertent separation of the top and bottom portions of the pod.

It is another object of the invention to provide a locking assembly for use with a pod of the type described that can be used with existing semiconductor processing equipment, and, in particular, with the locking mechanism release pins that are provided on typical current semiconductor processing equipment . These and other objects, features, and advantages will be apparent to those skilled in the art from the following detailed description, when read in conjunction with the accompanying drawings and appended claims .

Thus, according to a broad aspect of the invention, a pod is presented for carrying a cassette of the type used for conveying items used in an automated semiconductor manufacturing process in an associated processing apparatus. The pod has a top plate, a base adapted to be selectively received on the processing apparatus, four side walls, each in sealing engagement with the top plate and the base, and four corner posts, each attached to the top plate and the base. The top plate, the base, the side walls, and the corner posts are removably attached in sealed engagement to define a cassette receiving chamber. A bottom plate is provided for attachment to the cassette. The bottom plate is sized to fit into a receiving cavity in the base to locate the cassette in the cassette receiving chamber. A gasket is located between the bottom plate and the base when the bottom plate is located in the receiving cavity. Thus, when the bottom plate is located within the receiving cavity in the base, the cassette receiving chamber is substantially airtight.

The pod further may include a plurality of locking mechanisms mounted in the base. Each of the locking mechanisms includes a sliding member adapted to engage the bottom plate from within a slot therein when the bottom plate is located in the receiving cavity in the base.

The pod also may include a retaining member attached to the sliding member of at least one of the locking mechanisms. When the sliding members engage the bottom plate, the retaining member is moved in a direction toward the cassette to constrain movement of articles contained in the cassette.

According to another broad aspect of the invention, a method is presented for making a pod for carrying a cassette of the type used for conveying items used in an automated semiconductor manufacturing process in an associated processing apparatus. The method includes removably attaching a top plate, four side walls, four corner posts, and a base in sealing engagement to define a cassette receiving chamber. The method also includes providing a bottom plate for attachment to the cassette, sized to fit into a receiving cavity in the base to locate the cassette in the cassette receiving chamber. A gasket is also provided between the bottom plate and the base when the bottom plate is located in the receiving cavity, so that when the bottom plate is located within a receiving cavity in the base, the cassette receiving chamber is substantially airtight.

According to yet another broad aspect of the invention, a retainer is provided for constraining movement of planar items carried in a cassette and extending from the cassette from an open side thereof for slidable insertion and removal therein, the cassette being carried by a base removably positionable in a receiving enclosure. A locking mechanism is attached to the receiving enclosure for locking the base to the receiving enclosure when the cassette is positioned therein. At least one bar is provided extending in a substantially perpendicular direction with respect to the base. A mount is provided to which the at least one bar is attached, the mount being attached to the locking mechanism to be moved by actuation thereof in a direction substantially perpendicular to the .perpendicular direction with respect to the base. When the base is positioned in the receiving enclosure and the locking mechanism is configured to engage the base, the at least one bar is moved to a position in the receiving enclosure to engage the planar items substantially without sliding movement thereagainst . On the other hand, when the locking mechanism is configured to release the base, the at least one bar is moved to a position away from the planar items to allow the cassette, the planar items, and the base to be removed from the receiving enclosure.

According to yet another broad aspect of the invention, a locking mechanism is provided for selectively locking a base to a receiving enclosure. The locking mechanism includes a plate slidably carried in a slot in the receiving enclosure to be slidably positionable between a first plate position away from the base and a second plate position toward the base. The plate is located in a groove in the base when the plate is in the second plate position and being free from the base in the first plate position. A locking pin is carried within the receiving enclosure. The locking pin is movable between a first locking pin position away from the plate and a second locking pin position in which the locking pin extends into a hole in the plate to -constrain the plate from being slidably positionable. A spring is located between the locking pin and the receiving enclosure to bias the locking pin to the second locking pin position.

The plate is adapted to be received on a releasing pin to engage the locking pin within the hole in the plate and to move the locking pin to the first locking pin position.

The plate is further adapted to be slidably moved by the releasing pin between the first and second plate positions.

The plate may have an extension portion on a side of the receiving enclosure away from the base to fit into a slot in an adjacent structure to constrain movement of the receiving enclosure when the plate is in the first plate position. BRIEF DESCRIPTION OF THE DRAWINGS

The invention is illustrated in the accompanying drawings, in which:

Figure 1 is a perspective view of a cassette carrying pod, constructed in accordance with a preferred embodiment of the invention, with the bottom portion separated from the top portion.

Figure 2 is a side cross section of the cassette carrying pod of Figure 1 taken at 2-2. Figure 3 is a bottom view of the top portion of the cassette carrying pod of Figure 1, taken at 3-3.

Figure 4 is a side cross sectional view of one of the locking pins in the cassette carrying pod, taken at 4-4 in Figure 3. Figure 5 is a side cross sectional view of one of the locking pins of the cassette carrying pod of the invention, taken at 5-5 in Figure 3.

Figure 6 is a side elevation cross sectional view of one of the locking pins of the cassette carrying pod of the invention, taken at 6-6 in Figure 3.

Figure 7 is an exploded view of a portion of the locking pin assembly of one of the locking pin assemblies of the invention.

And figure 8 is an exploded perspective view of the cassette carrying pod, showing its relationship to a contained cassette and a base for its operative engagement.

In the various figures of the drawing, like reference numerals are used to denote like or similar parts. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the invention is intended for use in carrying a cassette of the type used to slidably receive one or more reticles of the type used in semiconductor processes, and, more particularly, in the production of semiconductor products using well known photolithographic techniques. Although the cassette is described with reference to carrying semiconductor photolithographic reticles, or the like, it should be understood that the invention it not limited to such cassette or such reticle containing uses. For example, semiconductor wafers themselves may be contained in an appropriately designed cassette. Thus, it will be appreciated by those skilled in the art that the pod of the invention can be used for receiving a cassette of the type designed for receiving reticles or other articles, semiconductor wafers, or other items used in the construction or fabrication of integrated circuits, for enabling the cassette to be transported or carried from one location to another, and for providing access to the cassettes in automated semiconductor equipment when the pod is properly positioned ' in relation thereto.

The reticles of the type received in the cassette 74 (see Figure 8) typically used in the fabrication of semiconductor devices typically have photolithographic masks (not shown) formed thereon. During the construction of a semiconductor product, for example, layers of photoresist may be deposited onto a semiconductor substrate that are exposed to ultraviolet or light of other wavelength through the masks provided on the reticles. The exposed portions of the photoresist material may then be chemically altered so that the semiconductor device can be subjected to chemical processes that remove portions determined by the mask pattern to enable dopants to be introduced into the semiconductor material, materials to be deposited at precise locations, and so on, according to the mask pattern. Typically a number of such mask pattern steps are required in the production of typical semiconductor devices; consequently, a number of masks are generally employed, requiring use of a multiple leveled reticle cassette of the type shown and described below in detail. Moreover, such processes are generally performed using robotic or other automated equipment (not shown) . Typically, for example, the reticles are loaded into the cassette 74 within a pod assembly of the type described. The entire assembly is then placed onto a portion of the semiconductor processing equipment, a portion of which is shown in Figure 8, and denoted by the reference numeral 70. The semiconductor processing equipment 70 typically includes a trap door 72 on which the pod is placed. When the locking members between the top and bottom portions of the pod are disengaged the entire base plate assembly of the pod and cassette containing the reticles is lowered through the trap door 72 to the interior of the processing equipment 70 to enable the semiconductor processes to be preformed in known manner. Upon completion of the processes, the base member and cassette are then returned to the upward position and locked within the upper portion of the pod 10.

More particularly, with reference now to Figures 1-8, details of the pod 10, according to a preferred embodiment of the invention are shown. With reference first to Figures 1-3 and 8, the pod 10 includes a top cover assembly 12 and a base member 14 onto which the top member 12 is securely receivable. A cassette 74, best seen in Figure 8, is generally attached to the base member 14 of the pod 10 to enable it to be carried thereby into processing equipment 70 after the base member 14 has been separated from a top portion 12 of the pod.

The top cover assembly 12 is modularly constructed. More particularly, the top cover assembly 12 is advantageously constructed of a number of individual replaceable parts to enable it to be repaired in the event of damage thereto. Still more particularly, the top member 12 includes a top plate 16 to which a carrying handle 18 is attached. Four side panels 20-23 are provided, which are held in place by corner posts 26-29, (element 29 being seen in the cut away portion of the top cover assembly 12 shown in Figure 1) .

The side panels 20-23 and corner posts 26-29 are attached to a base ring 30. In order to isolate the interior of the chamber 32 defined by the top cover assembly 12, the various members of the top cover assembly 12 preferably can be friction fit at their junctions into receiving slots 34, 36, 38, and 40 around the periphery of the base ring 30, wherein a substantially airtight seal is formed. The junctions can be further isolated by an elastomeric material (not shown) within receiving slots, if desired. For ease of assembly and disassembly in the original construction of the top cover assembly 12, and subsequent possible repair thereof, screws 42 are provided between the top plate 16 and the corner posts 26-29. Corresponding screws (not shown) are provided between the base ring 30 and corner posts 26-29.

It should be noted that the side panels 20-22 can be made of transparent plastic, as shown, or other suitable material. Additionally, the top plate 16 and corner members 26-29 also may be made of plastic, or other suitable material. The base ring 30 may be of plastic or other durable material that can withstand the various stresses that will be applied thereto, as will be apparent from the description below. The bottom plate number 14 is preferably of aluminum or other light weight metallic material.

The top cover assembly 12 is designed to be enclosed at its bottom portion by the base member 14. The base member 14 is sized to fit a receiving opening 48 in the bottom portion of the base ring 14, which can be seen particularly in Figure 2. In order to provide a sealing engagement between the base member 14 and base ring 30, an elastomeric member 50 is provided in a ring or groove 52 around the periphery of the base member 14. The elastomeric member 50 seats in a receiving groove 54 within the receiving opening 48 around the base ring 30.

Four locking assemblies 56, described below in greater detail, are arranged in the base ring 30. Each of the locking assemblies 56 includes a sliding member, or bar, 58 that, in sealed position, is received by a corresponding locking opening 60 in the base member 14. It should be noted that the bar 58 of the locking assembly 56 includes a tapered front face 100 to assist in proper engagement with the walls of the locking openings 60 in the base member 14.

When the top cover assembly 12 and base member 14 are in sealed engagement with the bars 58 properly inserted into the locking openings 60, the interior chamber 32 thereby created is essentially isolated from the external atmosphere. As a result, once the interior chamber 32 has been established with a particular clean atmosphere, that atmosphere can be easily maintained due to the sealed nature of the parts as described above. More particularly, as mentioned above, the pod 10 is adapted to carry a reticle cassette 74 in the interior chamber 32 thereof.

Thus, as best seen in Figure 8, a reticle cassette 74 may be attached to the base member 14 by screws or the like

(not shown) . The reticle cassette 74 has locating pins (not shown) that are received in holes 64 to enable precision location of the cassette 74 in relation to the base member 14. It should be also noted that although a cassette 74 of the type that is enabled to receive a slidable plurality of reticles 63 is illustrated, other types of cassettes can be equally advantageously employed, such as single reticle carrying cassettes, semiconductor wafer carrying cassettes, and so on.

Each of the locking assemblies 56 are identically constructed, the details of which are shown in Figures 2-7. Each of the locking assemblies 56 is formed in a block 80 of material that is received in a groove 82 in the base ring 30. Slots 84 are provided in the block 80 to receive the bars 58. Each of the bars 58 can be formed with a pair of upstanding stabilizing arms 86 and 88 to be received within the slots 84. Additionally, lower flanges 90 and 92 may be provided to receive the lower portion of the bar 58 to vertically constrain the entire assembly within the block 80.

Each bar 58 of the locking assemblies 56 includes a slot 94 on its bottom side, best seen in Figure 3. A hole 96 extends completely through the bar 58 to receive a locking pin 98 when the hole 96 is aligned therewith in a locked position, for example, when the base member 14 is received within the receiving opening 48 of the top cover assembly 12, to hold the forward portions 100 of the bar 58 in their engagement with the locking openings 60 of the base member 14. The locking pin 98 assures that when the base member 14 is received in the receiving opening 48 of the base ring 30, the base member 14 and the cassette 74 carried thereby cannot be accidentally or inadvertently removed from the top cover assembly 12. Although the inclusion of the locking pin 98 is preferable, it will be understood that in some applications it may be omitted, without obviating the operation of the locking assemblies 56.

When the back edge of the bar 58 is flush with the outside edge of the base ring 30, a positive visual indicia is given to the user to provides a positive indication that the locking assemblies 56 are securely in place, to assure the user that the base member 14 and cassette 74 carried thereby will not inadvertently separate from the top cover assembly 12. Moreover, the locking pin 98 provides assurance that the bar 58 cannot be inadvertently moved from its locked position at which the bar 58 engages the base member 14 within the locking openings 60, without positive engagement by a releasing pin, for example, that would be provided on the semiconductor processing equipment 70 with which the pod assembly 10 may be used.

On the other hand, once the pod assembly 10 is properly located on the semiconductor processing equipment 70, and the bar 58 retracted, portions of the bar 58 extend slightly beyond the outside edge of the base member 14. This provides a clear indication that the locking assembly 56 with which the extending bar is associated is not in its locked position. With the locking assemblies 56 in their unlocked configura- tions, the base member 14 and cassette 74 can be easily removed from the top member 12 to enable easy access to the contents of the cassette carried on the base member 14.

A spring 102 is provided to bias the locking pin 98 downwardly to enable it to enter the hole 96 and slot 94 in the bar 58, when the bar 58 is aligned in its locked position described above. This can best be seen, for example, in the cross-sectional view of a locking assembly 56 in Figure 4. The spring 102 engages the structure of the base ring 30 within the groove 82 in which the locking assembly structure is received. The locking assembly 56 may be held in place by screws 104.

In operation of the locking assemblies 56, with reference additionally to Figure 8, the semiconductor processing equipment 70 preferably includes a number of pins 108 that are contained within respective slots 110, and which are located so that when the pod 10 is lowered into position on the processing equipment 70, the pins 108 engage the pins 98 of the locking assembly 56, pushing them upward, and allowing the bars 58 to be slidably moved away from the locking slot 60 and into additional locking slots 112 provided on the processing equipment 70. Thus, in the location of the bar 58 away from the base number 14, the top cover assembly 12 is locked into engagement with the processing equipment 70. Concurrently, the base member 14 is free to be disengaged from the top cover assembly 12 to enable it and the cassette 74 that it carries to be moved down into the processing equipment 70.

If desired, to assist in stabilizing the structure of the cassette 74 that is selectively placeable within the top cover assembly 14, one or more spring members 77 may be attached to the top plate 16 to resiliently engage the top portion of the cassette 74 when it is contained within the chamber 32. In addition, to assist in maintaining the position of the reticles 63 within the cassette 74, a pair of engagement bars 76 is provided, details of which are best seen in Figures 2, 3, and 7. The reticle engaging bars 76 may be of plastic or other suitable material. The reticle engaging bars 76 operate in conjunction with a pair of the locking assemblies 56 to be moveable towards and away from the open reticle receiving side 62 of the cassette 74, as shown by the arrow 78 in Figure 2. It will be appreciated that in contrast to prior art structures in which the retaining bars which engaged the reticles within the cassette through a sliding movement against a spring biasing members, which resulted in the possible creation of contaminants within the enclosure, the reticle engaging bars 76 are merely moved towards or away from engagement with the reticles 63 directly with the actuation of the locking assemblies 56, without substantial friction or sliding motion against the edges of the reticles 63.

In addition to the foregoing, as mentioned above, the reticle engaging bars 76 are controlled by the action of the bar 58 within the block 80. Thus, a reticle locking assembly 120 is provided on the open side 62 of the cassette 74. The reticle locking assembly 120 includes a cross-member 122 onto which the upstanding reticle engaging bars 76 are attached by screws 124, or the like. A pair of spacers 126 are provided at each end of the cross member 122 to allow the cross-member 122 to be attached to the stabilizing arms 86 and 88 of the bar 58 by screws 130, or the like. An additional spacer 132 between the base ring 30 and spaces 126 may be provided if needed for proper adjustment.

The cross-member 122 is biased away from the block 80 by a spring 134, which may be contained in a keeper cylinder 136. Thus, it can be seen that when the bar 58 is in a position for locking or retaining the base member 14 in locked engagement with the top cover assembly 12, the cross-member 122 and reticle engaging bars 76 are moved into engagement with the reticles 63 within the cassette 74. On the other hand, when the bar 58 is moved to a position away from its engagement with the base member 14, the cross-member 122 and reticle engaging bars 76 are moved away from the engagement position with the reticles to enable the cassette to be freely moved out of the chamber 32 of the pod 10. Thus, the position of the reticle engaging bars 76 can be moved between the location shown in solid lines in Figure 3 and the location shown by dotted lines, in dependence upon the position of the bars 58.

In some applications, the electrostatic discharge (ESD) properties of the pod 10 may be of concern. Consequently, if desired, the various components of the pod 10 can be coated with an ESD coating (not shown) to increase the conductivity of the parts of the pod 10. It is noted that the semiconductor processing equipment 70 typically is maintained at a ground potential. As a result, once the pod 10 is properly ensconced on the semiconductor processing equipment 70, suitable ground contact is made between the various parts of the pod 10 and semiconductor processing equipment 70, thereby providing a current flow path to drain off any excess static charge that may have accumulated on any of the various parts of the pod 10. Although the invention has been described and illustrated with a certain degree of particularity, it is understood that the present disclosure has been made only by way of example, and that numerous changes in the combination and arrangement of parts can be resorted to by those skilled in the art without departing from the spirit and scope of the invention, as hereinafter claimed.

Claims

CLAIMS : 1. A pod for carrying a cassette of the type used for conveying items used in an automated semiconductor manufacturing process in an associated processing apparatus, comprising: a top plate; a base adapted to be selectively received on said processing apparatus; four side walls, each in sealing engagement with said top plate and said base; four corner posts, each attached to said top plate and said base; said top plate, said base, said side walls, and said corner posts being removably attached in sealed engagement to define a cassette receiving chamber; a bottom plate for attachment to said cassette, and sized to fit into a receiving cavity in said base to locate said cassette in said cassette receiving chamber; and a gasket located between said bottom plate and said base when said bottom plate is located in said receiving cavity, wherein when said bottom plate is located within the receiving cavity in said base, said cassette receiving chamber is substantially airtight.
2. The pod of claim 1, 1 further comprising a plurality of locking mechanisms mounted in said base, each of said locking mechanisms including a sliding member adapted to engage said bottom plate from within a slot therein when said bottom plate is located in said receiving cavity in said base.
3. The pod of claim 2 wherein said sliding member has a hole therethrough, and wherein said locking mechanism further comprises a locking pin and a bias spring to bias said locking pin into said hole when said bottom plate is located in said receiving cavity in said base.
4. The pod of claim 2 wherein said sliding member is sized to extend beyond said base away from said receiving cavity to enable said sliding member to engage said processing apparatus.
5. The pod of claim 2 further comprising a retaining member attached to said sliding member of at least one of said locking mechanisms, wherein when said sliding members engage said bottom plate, said retaining member is moved in a direction toward said cassette to constrain movement of articles contained in said cassette.
6. The pod of claim 1, 1 further comprising a handle on said top plate to facilitate carrying of said pod.
7. A method for making a pod for carrying a cassette of the type used for conveying items used in an automated semiconduc- tor manufacturing process in an associated processing apparatus, comprising: removably attaching a top plate, four side walls, four corner posts, and a base in sealing engagement to define a cassette receiving chamber; providing a bottom plate for attachment to said cassette, sized to fit into a receiving cavity in said base to locate said cassette in said cassette receiving chamber; and providing a gasket between said bottom plate and said base when said bottom plate is located in said receiving cavity, wherein when said bottom plate is located within a receiving cavity in said base, said cassette receiving chamber is substantially airtight.
8. A retainer for constraining movement of planar items carried in a cassette and extending from said cassette from an open side thereof for slidable insertion and removal therein, said cassette being carried by a base removably positionable in a receiving enclosure, comprising: a locking mechanism attached to said receiving enclosure for locking said base to said receiving enclosure when said cassette is positioned therein; at least one bar extending in a substantially perpendicu- lar direction with respect to said base; a mount to which said at least one bar is attached, said mount being attached to said locking mechanism to be moved by actuation thereof in a direction substantially perpendicular to said perpendicular direction with respect to said base; whereby when said base is positioned in said receiving enclosure and said locking mechanism is configured to engage said base said at least one bar is moved to a position in said receiving enclosure to engage said planar items substantially without sliding movement thereagainst, and when said locking mechanism is configured to release said base, said at least one bar is moved to a position away from said planar items to allow said cassette, said planar items, and said base to be removed from said receiving enclosure.
9. The retainer of claim 8 wherein said at least one bar comprises two parallel bars.
10. The retainer of claim 8 wherein said a locking mechanism comprises a pair of upstanding arms and wherein said mount comprises: a bar mounting member to carry said at least one bar; a pair of spacing members connected between said bar mounting member and said upstanding arms, and a spring between said bar mounting member and said receiving enclosure to bias said at least one bar in a direction toward said planar items.
11. The retainer of claim 10 wherein said a locking mechanism further comprises: a plate slidably carried in a slot in said receiving enclosure to be slidably positionable between a first plate position away from said base and a second plate position toward said base, said plate being located in a groove in said base when said plate is in said second plate position and being free from said base in said first plate position; a locking pin carried within said receiving enclosure, said locking pin being movable between a first locking pin position away from said plate and a second locking pin position in which said locking pin extends into a hole in said plate to constrain said plate from being slidably positionable; and a spring between said locking pin and said receiving enclosure to bias said locking pin to said second locking pin position.
12. The retainer of claim 11 wherein said plate is adapted to be received on a releasing pin to engage said locking pin within said hole in said plate and to move said locking pin to said first locking pin position.
13. A locking mechanism for selectively locking a base to a receiving enclosure, comprising: a plate slidably carried in a slot in said receiving enclosure to be slidably positionable between a first plate position away from said base and a second plate position toward said base, said plate being located in a groove in said base when said plate is in said second plate position and being free from said base in said first plate position; a locking pin carried within said receiving enclosure, said locking pin being movable between a first locking pin position away from said plate and a second locking pin position in which said locking pin extends into a hole in said plate to constrain said plate from being slidably positionable; and a spring between said locking pin and said receiving enclosure to bias said locking pin to said second locking pin position.
14. The locking mechanism of claim 13 wherein said plate is adapted to be received on a releasing pin to engage said locking pin within said hole in said plate and to move said locking pin to said first locking pin position.
15. The locking mechanism of claim 14 wherein said plate is further adapted to be slidably moved by said releasing pin between said first and second plate positions.
16. The locking mechanism of claim 14 wherein said plate has an extension portion on a side of said receiving enclosure away from said base to fit into a slot in an adjacent structure to constrain movement of said receiving enclosure when said plate is in said first plate position.
PCT/US2000/011101 2000-04-25 2000-04-25 Pod for carrying reticle cassette WO2001081203A1 (en)

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PCT/US2000/011101 WO2001081203A1 (en) 2000-04-25 2000-04-25 Pod for carrying reticle cassette
AU4370700A AU4370700A (en) 2000-04-25 2000-04-25 Pod for carrying reticle cassette

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US1617813A (en) * 1926-03-15 1927-02-15 Judge Thomas Charles Sash fastener
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US1617813A (en) * 1926-03-15 1927-02-15 Judge Thomas Charles Sash fastener
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US4739882A (en) * 1986-02-13 1988-04-26 Asyst Technologies Container having disposable liners
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