Abstract:
A conveyor system is provided. The conveyor system includes a threshold assembly. The threshold assembly has a base plate that is secured to a floor, and the threshold assembly has a channel that is formed between two support beams that are secured to a base plate. A plurality of threshold center plates are provided, which span and enclose the channel formed by the support beams, such that each threshold assembly includes a modular printed circuit board that fits within the channel and is enclosed within the channel by threshold center plates. And, multiple conveyor segments are mountable to the threshold assembly. Other systems components and methods for making and operating the same are provided.

Description:
CLAIM OF PRIORITY 
     The present application claims priority under 35 U.S.C. §119(e) from U.S. Provisional Patent Application No. 61/043,092, filed Apr. 7, 2008, which is incorporated by reference in its entirety for all purposes. 
    
    
     BACKGROUND OF THE INVENTION 
     Description of the Related Art 
     There are several ways that semiconductor wafer containers are transported in a semiconductor fabrication facility (“fab”). A system for transporting a container is often referred to as an Automated Material Transport System (“AMHS”) or simply as a material transport system. A material transport system may refer to a part or all of the overall system. A fab may use only one type of AMHS throughout the fab, or there may be different types of AMHS in certain areas, or different types of AMHS for different transportation functions. Some of these AMHS types use vehicles to hold the container as it is being transported, such as a rail guided vehicle (RGV) or an automated guided vehicle (AGV). Material transport systems utilizing RGVs or AGVs require managing empty vehicles to arrange their arrival at sites where containers are to be picked up. Waiting for the arrival of such vehicles causes AMHS delays and the management of the vehicle movement increases the complexity of the AMHS. The same issues exist when moving containers with an Overhead Hoist Transport (OHT) system. 
     Conveyor systems are more efficient at moving containers within a fab without any, or a minimum number of, vehicle delays, and do not have to manage empty vehicles. Conveyors directly move the containers without any material or mechanical interface that comes between the conveyor surfaces and the container surfaces. Unless the conveyor is full, it is capable of immediately receiving a container for transport. For these, and other, reasons, conveyors may provide a very high throughput AMHS. 
     One example of a conveyor system is disclosed in U.S. Pat. No. 6,223,886, entitled “Integrated Roller Transport Pod and Asynchronous Conveyor,” which is owned by Asyst Technologies, Inc., and is incorporated in its entirety herein. The drive rail  12  includes a drive system, generally designated at  38  in  FIG. 1A , for propelling a container  2  along the rails  12 . The drive system  38  includes a plurality of separate drive assemblies  40 . Each drive assembly  40  includes a plurality of drive wheels  42  which frictionally engage the underside of the container  2  to propel the container  2  along the drive rail  12  for a specific zone Z. As shown in  FIG. 1A , the drive assemblies  40  are located along the rail such that the separation between the outermost drive wheels  42  of adjacent drive assemblies  40  is substantially equal to the spacing between the drive wheels  42  of the individual drive assembly  40 . The drive wheels  42  project upwardly from the drive rail housing such that it is the drive wheels  42  of the rail  12  which directly support the transport container  2 . The wheels  42  are preferably mounted at approximately the same height to minimize tipping or rocking of the container  2  as it is moved along the rails  12 . It is also known within the art to individually mount a passive wheel  43  between each drive wheel  42  (as shown in  FIG. 1A ). 
     It would be advantageous to provide a conveyor system that improves the performance of a conventional conveyor and reduces the costs of AMHS conveyor systems. The present invention provides such a conveyor. 
     In view of the forgoing, there is a need for improved modularity in order to reduce downtime and improve serviceability. 
     SUMMARY 
     A conveyor system made up from multiple modular conveyor segments is disclosed. The conveyor system can be viewed as a threshold assembly and individual conveyor segments. The threshold assembly can include a base plate that is secured to a floor. Also included in the threshold assembly is a channel that is formed between two support beams secured to the base plate. Spanning and enclosing the channel formed by the support beams are numerous threshold center plates. In one embodiment, the threshold assembly also includes a modular printed circuit board that fits within the channel and is enclosed within the channel by a threshold center plate. In some embodiments, it is possible for the modular printed circuit board to be mounted to the threshold center plate. 
     The individual conveyor segments can include drive motors, belts and sensors mounted to space frames and a kinematic plate. The kinematic plate enables the entire conveyor segment to be aligned and leveled before being secured to the threshold assembly. Features on the threshold center plate receive kinematic pins passed through the kinematic plate. The kinematic pins provide three-axis of adjustment of individual conveyor segment to ensure proper alignment and leveling irrespective of the conditions of the floor. Once aligned, the kinematic pins can be locked into position so the conveyor segment can be removed and replaced in a repeatable position. For example, when the conveyor segment is removed for maintenance or service and returned, the locked kinematic pins will place the conveyor segment in the same position so additional or repeated alignment is not necessary. 
     In one embodiment, the conveyors can be used in a semiconductor fabrication environment transporting Front Opening Unified Pods (FOUPs) between various fabrication tools. To minimize downtime, perform routine maintenance, or provide manufacturing flexibility, the fabrication tools may need to be moved. As the conveyors are anchored to the floor, individual conveyor assemblies can be removed from the threshold assembly to facilitate movement of fabrication tools. To further facilitate the movement of fabrication tools the profile of the threshold assembly can be minimized to allow wheeled equipment to be easily rolled over the threshold assembly. In one embodiment, the threshold assembly profile is reduced by using angled support beams that taper to a thinner cross-section at the interface between the base plate and the support beams. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention, together with further advantages thereof, may best be understood by reference to the following description taken in conjunction with the accompanying drawings. 
         FIG. 1A  provides a side elevation view of a conveyor, according to the prior art. 
         FIG. 1B  illustrates a conveyor made up of multiple conveyor segments. The individual conveyor segments can include controllers that can be networked and controlled by a computer. The conveyor can be configured to transport Front Opening Unifed Pods (FOUPs) to tools via load ports. 
         FIG. 2  is an exemplary view of a FOUP on a conveyor made up of multiple conveyor segments. 
         FIGS. 3A-3C  are different views of support beams, a conveyor assembly and a mounting assembly. 
         FIG. 3D  is a view of the mounting assembly that may include a threshold center plate and a modular printed circuit board. The mounting assembly may be attached to the support beams. 
         FIG. 4  illustrates an exploded view of the mounting assembly including a base plate and covers. Also illustrated are power and communication cables that can be used to transmit power and control signals between modular printed circuit boards. 
         FIG. 5  is an exemplary illustration of a conveyor segment looking through the conveyor assembly. The kinematic plate is shown along with kinetic pins and fasteners. Also shown is a power and communications connector from the bus. 
         FIG. 6  is side view of a conveyor segment that illustrates the kinematic pins and fasteners used to locate and secure the conveyor assembly to the mounting assembly. 
         FIG. 7  is a front view of a conveyor segment, support beams, and base plate. This figure illustrates how the base plates, support beams and conveyor segment enclose the modular PCB. 
         FIG. 8  is an exemplary bottom view of the conveyor without the base plate. This view illustrates how the bus can interconnect the modular PCBs of the conveyor segments. Also shown are the covers that prevent the bus from exposure between the conveyor segments. 
         FIG. 9  is a partially exploded view of multiple conveyor segments and the mounting assembly. In this view the base plate, support beams, threshold center plate, modular PCB and covers are referred to as a threshold assembly. 
         FIG. 10A  is view of the conveyor and base plate. 
         FIG. 10B  is a view of a load port conveyor assembly  104   a ′. The load port conveyor assembly includes a feature or geometry that allows a load port to lift a FOUP off of the conveyor. 
         FIG. 11  is an exemplary view of a processing area that can use multiple conveyors having multiple conveyor segments. The conveyors can be used to transport FOUPs to and from various tools and stacker machines. 
     
    
    
     DETAILED DESCRIPTION 
     An invention is disclosed for securing a conveyor system in a repeatable manner to enable rapid servicing and maintenance. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced without some or all of these specific details. In other instances, well known process steps have not been described in detail in order not to unnecessarily obscure the present invention. 
       FIG. 1B  shows an exemplary overhead view of a processing area  100  in accordance with one embodiment of the present invention. The processing area  100  can include a conveyor  102  that is made up of multiple conveyor segments  104 . The conveyor  102  can be configured to transport materials to and from tool  112  and tool  108 . In one embodiment, semi-conductor substrates are transported along the conveyor  102  in Front Opening Unified Pods (FOUPs) (not shown). A FOUP traveling along the conveyor  102  can be loaded into load port  106  or load port  110  and the semi-conductor substrates can be processed within tool  108  or tool  112  respectively. 
     In one embodiment, the tool  108  and the tool  112  can be machines used in the processing of semiconductor substrates. Tool  108  and tool  112  may be the same tool or entirely different tools that perform similar or different functions. The embodiment illustrated in  FIG. 1B  shows each tool  108 / 112  having three load ports  106 / 110 . This is merely illustrative of one embodiment and in other embodiments, more or fewer load ports could be associated with each respective tool. 
     In one embodiment, the conveyor segments  104  are modular assemblies that permit rapid service and maintenance of the conveyor  102 . To facilitate rapid service and maintenance, each conveyor segment  104  can include belt modules, or belt cartridges that can be rapidly removed and replaced in order to minimize downtime for the conveyor  102 . Each conveyor segment  104  can also include a motor to drive the belt modules along with a computer controller to activate and deactivate the motor. In one embodiment, the computer controllers for the conveyor segments  104  can be networked using a bus system to provide power and communications between the individual conveyor segments. Communications to the conveyer  102  can be performed using a network  114  that allows a computer  118  to monitor and control individual conveyor segments  104 . 
       FIG. 2  is an exemplary view of the processing area  100  in accordance with one embodiment of the present invention. In this exemplary embodiment, four conveyor segments  104  make up the conveyor  102 . A FOUP  206  is shown on the conveyor  102  along with some belt modules  204  within the conveyor segments  104 . In one embodiment a drive motor provides movement to a belt module on one side of the conveyor segment and a constant velocity driveshaft  202  is used to transmit movement to the belt module on the other side of the conveyor segment. Also shown in  FIG. 2  is support beam  200 . 
       FIG. 3A-3C  shows a conveyor segment  104  as a conveyor assembly  104   a  along with mounting assembly  104   b  and support beams  200 , in accordance with an exemplary embodiment of the present invention. The support beams  200  define a channel that accommodates the mounting assembly  104   b . The lower assembly  104   b  includes a modular Printed Circuit Board (PCB)  306  and a threshold center plate  304 . The channel between the support beams  200  accommodates the modular PCB  306  while the threshold center plate  304  covers the modular PCB  306 . The threshold center plate  304  also is used to mount the conveyor assembly  104   a  to the mounting assembly  104   b.    
     The conveyor assembly  104   a  includes two space frames  302  spaced apart by a kinematic plate  300 . In one embodiment, three kinematic pins  310   a ,  310   b , and  310   c  pass through the kinematic plate and rest against defined geometry on threshold center plate  304 . The kinematic pins  310   a ,  310   b , and  310   c  are used to initially align the conveyor segment  104  via pitch (Y-axis) and roll (X-axis). In one embodiment, the defined geometry on the threshold center plate allows fine linear adjustments of the entire conveyor assembly  104   a  along the length of the X-axis. Once the kinematic pins  310   a - 310   c  have been aligned, the kinematic pins for the particular conveyor segment  104  can be locked into the aligned position. Thus, the conveyor assembly  104   a  can be removed and the locked kinematic pins can be used to precisely relocate the conveyor assembly  104   a  onto the threshold center plate  304  without required additional alignment. 
       FIG. 3D  is an exemplary view of the lower assembly  104   b  along with the support beams  200  in accordance with one embodiment of the present invention. The modular PCB  306  provides power and communications to the conveyor assembly  104   a  and is enclosed by the support beams  200  and the threshold center plate  304 . 
       FIG. 4  is an exemplary exploded view of the mounting assembly  104   b  along with covers  409  and base plate  400 , in accordance with one embodiment of the present invention. In one embodiment, the base plate  400  can be secured to a floor and the support beams  200  can be affixed to the base plate  400 . The modular PCB  306  can then be completely enclosed between the base plate  400 , the support beams  300  and the threshold center plate  304 . In this embodiment, the modular PCB  306  is shown with power and communication cables  402  and is attached to a bottom side of the threshold center plate  304 . Covers  409  can be used to cover the power and communications cable  402  between the threshold center plates  304 . A complete mounting assembly  104   b  is shown enclosed within the support beams  200 . 
       FIG. 5  is an exemplary view of the kinematic plate  300  through the top of the conveyor assembly  104   a . This view shows the kinematic pins  310   a - 310   c  along with screws  500   a - 500   c . As previously discussed, the kinematic pins are used to initially align the conveyor assembly  104   a  and then to repeatedly relocate the conveyor assembly  104   a  after removal. The fasteners  500   a - 500   c  are used to secure the conveyor assembly  104   a  to the threshold center plate  304 . Thus, the fasteners  500   a - 500   c  pass through the kinematic plates and mate with features on the threshold center plate. 
     In one embodiment, the fasteners  500   a - 500   c  are removed and the entire conveyor assembly  104   a  can be removed for servicing. Once servicing is completed, the kinematic pins help relocate the conveyor assembly  104   a  on the threshold center plate and fasteners  500   a - 500   c  are used to secure the conveyor assembly  104   a  to the threshold center plate. Also shown in  FIG. 5  is a bus  502  that provides all power and communications needs for the conveyor segment  104 . Also shown are multiple space frames  302  and constant velocity drive shafts  202   
       FIG. 6  illustrates a side view of a conveyor segment  104  in accordance with one embodiment of the present invention. Kinematic pins  310   c  and  310   b  can be seen along with fasteners  500   c  can be seen passing through the kinematic plate  300 . Fastener  500   a  is also visible passing through the kinematic plate  300  and the kinematic pin  300   a  is partially visible behind the fastener  500   a . The threshold center plate can be formed with features to accommodate the kinematic pins  310   a - 310   c . Such features can include grooves, slots or holes. The features in the threshold center plate can assist in aligning and leveling the conveyor assembly  104   a  using the kinematic pins  310   a - 310   c . In one embodiment, the kinematic pins can be locked into position using jam-nuts once the conveyor assembly  104   a  is properly leveled and aligned. 
     When the kinematic pins are locked into position, it does not mean that the conveyor assembly  104   a  is secured or locked into position. Rather, locking the kinematic pins into position results in the kinematic pins being able to relocate the conveyor assembly  104   a  back in the level and aligned position after being removed for service or maintenance. 
     The fasteners  500   a - 500   c  are used to secure the conveyor assembly  104   a  to the threshold center plate. The fasteners  500   a - 500   c  prevent the conveyor assembly  104   a  from being knocked over, jostled, or vibrated when a FOUP traverses the conveyor segment  104 . Also shown in is the bus  502  that provides power and communications for the conveyor segment  104 . 
       FIG. 7  shows an end view of the conveyor segment  104  along with the support beams  200  and the base plate  400  in accordance with one embodiment of the present invention. This view shows how the modular PCB  306  is attached to the threshold center plate  304  and enclosed by the base plate  400 , support beams  200  and cover  409 . 
       FIGS. 8-10A  are various views of multiple conveyor segments in accordance with embodiments of the present invention.  FIG. 8  illustrates the location of the modular PCB  306  between the support beams  200  when the base plate is not shown.  FIG. 8  also illustrates that the support beams  200  can be supplied in lengths different than those of the conveyor segments. In one embodiment, the power and communications cables  402  can allow power to be fed from both ends of the conveyor system to improve system functionality. For example, you can rapidly remove multiple portions of assembly  104   a  from the threshold assembly while retaining functionality throughout the remaining conveyor. In other embodiments, each modular PCB  306  is connected to its neighbor modular PCB using a ribbon cable for communications (either high speed serial or Ethernet) and larger gauge wires for power and ground. 
     In some embodiments, a dual supply bus/power supply is available so that in the event of a power failure from either a single line or a power supply, an alternate power line will supply power to the conveyor to maintain operation. Each conveyor assembly can be attached to ground via the kinematic pins touching the threshold center plate. Support beams that provide easy access by wheeled equipment support the threshold center plate. In one embodiment, the support beams are anchored to a base plate using double-sided tape. The installation of the support beams may require the use of an assembly fixture in order to provide accurate alignment and leveling.  FIG. 10  illustrates that the conveyor module has a length X of 500 mm However, this is merely one embodiment and the length of the conveyor modules is not fixed. In other embodiments, a conveyor can be made from conveyor modules of different or similar lengths as determined by individual installation requirements. 
       FIG. 10B  illustrates an exemplary load port conveyor assembly  104   a ′ adjacent to conveyor assemblies  104   a , in accordance with one embodiment of the present invention. The load port conveyor assembly  104   a ′ includes a cutout  1010  that allows load ports to pick-up and/or drop-off a FOUP traversing the conveyor. The geometry of cutout  1010  is intended to be exemplary and should not be considered limiting. A load port conveyor assembly  104   a ′ can include other features or geometries that provide a load port access to a FOUP traveling along the conveyor. 
       FIG. 11  is an exemplary overhead view of a portion of a process area  100  in accordance with one embodiment of the present invention. In this embodiment, conveyors  102  can form a grid to supply FOUPs to various tools  108  via load ports or stackers  1100 . Where conveyors  102  intersect, a director  1102  can be used to rotate and direct FOUPs to a desired location. The configuration of conveyors  102 , tools and directors  1102  shown in  FIG. 11  is intended to be exemplary and is not intended to be considered comprehensive of process area  100  layouts. 
     As previously discussed, the conveyors  102  can include integrated networked communications. These communications allow individual conveyor segments to be controlled by a computer system via a network. The computer system can also execute software that allows individual FOUPs to be transported and tracked stopped at load ports, stackers, or while on the conveyors  102 . 
     The invention may be practiced with other computer system configurations including, but not limited to, computing devices, hand-held devices, microprocessor systems, microprocessor-based or programmable consumer electronics, minicomputers, mainframe computers and the like. The invention may also be practiced in distributing computing environments where tasks are performed by remote processing devices that are linked through a network. 
     With the above embodiments in mind, it should be understood that the invention may employ various computer-implemented operations involving data stored in computer systems. These operations are those requiring physical manipulation of physical quantities. Usually, though not necessarily, these quantities take the form of electrical or magnetic signals capable of being stored, transferred, combined, compared, and otherwise manipulated. Further, the manipulations performed are often referred to in terms, such as producing, identifying, determining, or comparing. 
     Any of the operations described herein that form part of the invention are useful machine operations. The invention also relates to a device or an apparatus for performing these operations. The apparatus may be specially constructed for the required purposes, such as the carrier network discussed above, or it may be a general purpose computer selectively activated or configured by a computer program stored in the computer. In particular, various general purpose machines may be used with computer programs written in accordance with the teachings herein, or it may be more convenient to construct a more specialized apparatus to perform the required operations. 
     The invention can also be embodied as computer readable code on a computer readable medium. The computer readable medium may be any data storage device that can store data, which can thereafter be read by a computer system. Examples of the computer readable medium include hard drives, network attached storage (NAS), read-only memory, random-access memory, FLASH based memory, CD-ROMs, CD-Rs, CD-RWs, DVDs, magnetic tapes, and other optical and non-optical data storage devices. The computer readable medium can also be distributed over a network coupled computer systems so that the computer readable code may be stored and executed in a distributed fashion. 
     Although the foregoing invention has been described in some detail for purposes of clarity of understanding, it will be apparent that certain changes and modifications can be practiced within the scope of the appended claims. Accordingly, the present embodiments are to be considered as illustrative and not restrictive, and the invention is not to be limited to the details given herein, but may be modified within the scope and equivalents of the appended claims. In the claims, elements and/or steps do not imply any particular order of operation, unless explicitly stated in the claims.