Patent Publication Number: US-9884726-B2

Title: Semiconductor wafer handling transport

Description:
RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 12/025,477 filed Feb. 4, 2008 (Now U.S. Pat. No. 8,672,605) which is a continuation of U.S. application Ser. No. 11/679,829 filed Feb. 27, 2007 which claims the benefit of U.S. Prov. App. No. 60/777,443 filed on Feb. 27, 2006; U.S. Prov. App. No. 60/779,684 filed on Mar. 5, 2006; U.S. Prov. App. No. 60/779,707 filed on Mar. 5, 2006; U.S. Prov. App. No. 60/779,478 filed on Mar. 5, 2006; U.S. Prov. App. No. 60/779,463 filed on Mar. 5, 2006; U.S. Prov. App. No. 60/779,609 filed on Mar. 5, 2006; U.S. Prov. App. No. 60/784,832 filed on Mar. 21, 2006; U.S. Prov. App. No. 60/746,163 filed on May 1, 2006; U.S. Prov. App. No. 60/807,189 filed on Jul. 12, 2006; and U.S. Prov. App. No. 60/823,454 filed on Aug. 24, 2006; and 
     U.S. application Ser. No. 11/679,829 is a continuation-in-part of U.S. application Ser. No. 10/985,834 filed on Nov. 10, 2004 (now U.S. Pat. No. 7,458,763) which claims the benefit of U.S. Prov. App. No. 60/518,823 filed on Nov. 10, 2003 and U.S. Prov. App. No. 60/607,649 filed on Sep. 7, 2004. 
     The entire contents of each of the foregoing applications is incorporated herein by reference. 
    
    
     BACKGROUND 
     1. Field of the Invention 
     The invention herein disclosed generally relates to semiconductor processing systems, and specifically relates to vacuum semiconductor processing work piece handling and transportation. 
     1. Description of the Related Art 
     Current semiconductor manufacturing equipment takes several different forms, each of which has significant drawbacks. Cluster tools, machines that arrange a group of semiconductor processing modules in a radius about a central robotic arm, take up a large amount of space, are relatively slow, and, by virtue of their architecture, are 
     limited to a small number of semiconductor process modules, typically a maximum of about five or six. Linear tools, while offering much greater flexibility and the potential for greater speed than cluster tools, do not fit well with the current infrastructure of most current semiconductor fabrication facilities. Moreover, linear motion of equipment components within the typical vacuum environment of semiconductor manufacturing leads to problems in current linear systems, such as unacceptable levels of particles that are generated by friction among components. Several hybrid architectures exist that use a combination of a radial process module arrangement and a linear arrangement. 
     As semiconductor manufacturing has grown in complexity, it becomes increasingly necessary to transfer wafers among a number of different process modules or clusters of process modules, and sometimes between tools and modules that are separated by significant distances. This poses numerous difficulties, particularly when wafers are transferred between separate vacuum processing facilities. Transfers between vacuum environments, or between a vacuum and other processing environments often results in increased risk of particle contamination (due to the pumping and venting of wafers in load locks) as well as higher thermal budgets where wafers are either heated or cooled during transfers. 
     There remains a need for improved wafer transport and handling system for use in semiconductor manufacturing environments. 
     SUMMARY 
     Provided herein are methods and systems used for improved semiconductor manufacturing handling, and transport. Modular wafer transport and handling facilities are combined in a variety of ways deliver greater levels of flexibility, utility, efficiency, and functionality in a vacuum semiconductor processing system. Various processing and other modules may be interconnected with tunnel-and-cart transportation systems to extend the distance and versatility of the vacuum environment. Other improvements such as bypass thermal adjusters, buffering aligners, batch processing, multifunction modules, low particle vents, cluster processing cells, and the like are incorporated to expand functionality and improve processing efficiency. 
     As used herein, “robot” shall include any kind of known robot or similar device or facility that includes a mechanical capability and a control capability, which may include a combination of a controller, processor, computer, or similar facility, a set of motors or similar facilities, one or more resolvers, encoders or similar facilities, one or more mechanical or operational facilities, such as arms, wheels, legs, links, claws, extenders, grips, nozzles, sprayers, end effectors, actuators, and the like, as well as any combination of any of the above. One embodiment is a robotic arm. 
     As used herein “drive” shall include any form of drive mechanism or facility for inducing motion. In embodiments it includes the motor/encoder section of a robot. 
     As used herein, “axis” shall include a motor or drive connected mechanically through linkages, belts or similar facilities, to a mechanical member, such as an arm member. An “N-axis drive” shall include a drive containing N axes; for example a “2-axis drive” is a drive containing two axes. 
     As used herein, “atm” shall include a passive or active (meaning containing motors/encoders) linkage that may include one or more arm or leg members, bearings, and one or more end effectors for holding or gripping material to be handled. 
     As used herein, “SCARA arm” shall mean a Selectively Compliant Assembly Robot Arm (SCARA) robotic arm in one or more forms known to those of skill in the art, including an arm consisting of one or more upper links connected to a drive, one or more lower links connected through a belt or mechanism to a motor that is part of the drive, and one or more end units, such as an end effector or actuator. 
     As used herein, “turn radius” shall mean the radius that an arm fits in when it is fully retracted. 
     As used herein, “reach” shall include, with respect to a robotic arm, the maximum reach that is obtained when an arm is fully extended. Usually the mechanical limit is a little further out than the actual effective reach, because it is easier to control an arm that is not completely fully extended (in embodiments there is a left/right singularity at full extension that can be hard to control). 
     As used herein, “containment” shall mean situations when the arm is optimally retracted such that an imaginary circle can be drawn around the arm/end effector/material that is of minimum radius. 
     As used herein, the “reach-to-containment ratio” shall mean, with respect to a robotic arm, the ratio of maximum reach to minimum containment. 
     As used herein, “robot-to-robot” distance shall include the horizontal distance between the mechanical central axis of rotation of two different robot drives. 
     As used herein, “slot valve” shall include a rectangular shaped valve that opens and closes to allow a robot arm to pass through (as opposed to a vacuum (isolation) valve, which controls the pump down of a vacuum chamber). For example, the SEMI E21.1-1296 standard (a published standard for semiconductor manufacturing) the slot valve for 300 mm wafers in certain semiconductor manufacturing process modules has an opening width of 336 mm, a opening height of 50 mm and a total valve thickness of 60 mm with the standard also specifying the mounting bolts and alignment pins. 
     As used herein, “transfer plane” shall include the plane (elevation) at which material is passed from a robot chamber to a process module chamber through a slot valve. Per the SEMI E21.1-1296 standard for semiconductor manufacturing equipment the transfer plane is 14 mm above the slot valve centerline and 1100 mm above the plane of the factory floor. 
     As used herein, “section” shall include a vacuum chamber that has one or more robotic drives in it. This is the smallest repeatable element in a linear system. 
     As used herein, “link” shall include a mechanical member of a robot arm, connected on both ends to another link, an end effector, or the robot drive. 
     As used herein, “L1,” “L2”, “L3” or the like shall include the numbering of the arm links starting from the drive to the end effector. 
     As used herein, “end effector” shall include an element at an active end of a robotic arm distal from the robotic drive and proximal to an item on which the robotic arm will act. The end effector may be a hand of the robot that passively or actively holds the material to be transported in a semiconductor process or some other actuator disposed on the end of the robotic arm. 
     As used herein, the term “SCARA arm” refers to a robotic arm that includes one or more links and may include an end effector, where the arm, under control, can move linearly, such as to engage an object. A SCARA arm may have various numbers of links, such as 3, 4, or more. As used herein, “3-link SCARA arm” shall include a SCARA robotic arm that has three members: link one (L1), link two (L2) and an end effector. A drive for a 3-link SCARA arm usually has 3 motors: one connected to L1, one to the belt system, which in turn connects to the end effector through pulleys and a Z (lift) motor. One can connect a fourth motor to the end effector, which allows for some unusual moves not possible with only three motors. 
     As used herein, “dual SCARA arm” shall include a combination of two SCARA arms (such as two 3 or 4-link SCARA arms (typically designated A and B)) optionally connected to a common drive. In embodiments the two SCARA arms are either completely independent or share a common link member L1. A drive for a dual independent SCARA arm usually has either five motors: one connected to L1-A, one connected to L1-B, one connected to the belt system of arm A, one connected to the belt system of arm B, and a common Z (lift) motor. A drive for a dual dependent SCARA arm usually has a common share L1 link for both arms A and B and contains typically four motors: one connected to the common link L1, one connected to the belt system for arm A, one connected to the belt system for arm B, and a common Z (lift) motor. 
     As used herein, “4-link SCARA arm” shall include an arm that has four members: L1, L2, L3 and an end effector. A drive for a 4-link SCARA arm can have four motors: one connected to L1, one to the belt systems connected to L2 and L3, one to the end effector and a Z motor. In embodiments only 3 motors are needed: one connected to L1, one connected to the belt system that connects to L2, L3 and the end effector, and a Z motor. 
     As used herein, “Frog-leg style arm” shall include an arm that has five members: L1A, L1B, L2A, L3B and an end effector. A drive for a frog-leg arm can have three motors, one connected to L1A—which is mechanically by means of gearing or the like connected to L1B—, one connected to a turret that rotates the entire arm assembly, and a Z motor. In embodiments the drive contains three motors, one connected to L1A, one connected to L1B and a Z motor and achieves the desired motion through coordination between the motors. 
     As used herein, “Dual Frog-leg style arm” shall include an arm that has eight members L1A, L1B, L2A-1, L2A-2, L2B-1, L2B-2 and two end effectors. The second link members L2A-1 and L2B-1 form a single Frog-leg style arm, whereas the second link members L2A-2 and L2B-2 also form a single Frog-leg style arm, however facing in an opposite direction. A drive for a dual frog arm may be the same as for a single frog arm. 
     As used herein, “Leap Frog-leg style arm” shall include an arm that has eight members L1A, L1B, L2A-1, L2A-2, L2B-1, L2B-2 and two end effectors. The first link members L1A and L1B are each connected to one of the motors substantially by their centers, rather than by their distal ends. The second link members L2A-1 and L2B-1 form a single Frog-leg style arm, whereas the second link members L2A-2 and L2B-2 also form a single Frog-leg style arm, however facing in the same direction. A drive for a dual frog arm may be the same as for a single frog arm. 
     Disclosed herein are methods and systems for combining a linkable, flexible robotic system with a vacuum tunnel system using moveable carts for carrying one or more wafers in vacuum between process modules. The vacuum tunnel cart may be employed to transfer wafers between process modules or clusters, while a linkable robotic system is employed within each module or cluster for local wafer handling. The carts may employ any transportation medium suitable for a vacuum environment, such as magnetic levitation/propulsion. 
     Disclosed herein are also various configurations of vacuum transport systems in which heterogeneous handling systems are combined in a modular fashion to allow for more diverse functionality within a single process environment. In general, robots may be provided for wafer handling inside and between process modules that are in proximity to each other, while allowing for rapid, convenient transport of wafers between process cells that are relatively distant. Such heterogeneous handling systems may include, for example, systems in which robotic arms, such as SCARA arms, are used to handle wafers within process modules or clusters, while carts or similar facilities are used to transport wafers between process modules or clusters. A cart or similar facility may include a levitated cart, a cart on a rail, a tube system, or any of a wide variety of cart or railway systems, including various embodiments disclosed herein. 
     The methods and systems disclosed herein also include various configurations of robot handling systems in combination with cart systems, including ones in which cart systems form “U” and “T” shapes, circuits, lines, dual linear configurations (including side-by-side and above and below configurations) and the like. 
     Disclosed herein are methods and systems for supporting vacuum processing and handling modules in vacuum semiconductor processing systems. The pedestal support systems herein disclosed may precisely position vacuum modules to facilitate proper vacuum sealing between adjacent modules. In embodiments, the pedestal&#39;s cylindrical shape affords opportunity for convenient manufacturing methods while providing stability to the supported vacuum module with a small footprint. 
     In embodiments, the pedestal support system further may incorporate a robot motor mechanism for a robot operating within the vacuum module, further reducing the overall size and cost of the vacuum processing system. 
     A pedestal support system with a rolling base may also provide needed flexibility in reconfiguring processing and handling modules quickly and cost effectively. 
     These and other systems, methods, objects, features, and advantages of the present invention will be apparent to those skilled in the art from the following detailed description of the preferred embodiment and the drawings. All documents mentioned herein are hereby incorporated in their entirety by reference. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       The foregoing and other objects and advantages of the invention will be appreciated more fully from the following further description thereof, with reference to the accompanying drawings, wherein: 
         FIG. 1  shows equipment architectures for a variety of manufacturing equipment types. 
         FIG. 2  shows a conventional, cluster-type architecture for handling items in a semiconductor manufacturing process. 
         FIGS. 3A and 3B  show a series of cluster-type systems for accommodating between two and six process modules. 
         FIG. 4  shows high-level components of a linear processing architecture for handling items in a manufacturing process. 
         FIG. 5  shows a top view of a linear processing system, such as one with an architecture similar to that of  FIG. 4 . 
         FIGS. 6A and 6B  show a 3-link SCARA arm and a 4-link SCARA arm. 
         FIG. 7  shows reach and containment characteristics of a SCARA arm. 
         FIG. 8  shows high-level components for a robot system. 
         FIG. 9  shows components of a dual-arm architecture for a robotic arm system for use in a handling system. 
         FIG. 10  shows reach and containment capabilities of a 4-link SCARA arm. 
         FIGS. 11A and 11B  show interference characteristics of a 4-link SCARA arm. 
         FIG. 12  shows a side view of a dual-arm set of 4-link SCARA arms using belts as the transmission mechanism. 
         FIGS. 13A, 13B, and 13C  show a dual-arm set of 4-link SCARA arms using a spline link as the transmission mechanism. 
         FIG. 14  shows an external return system for a handling system having a linear architecture. 
         FIG. 14 a    shows a U-shaped configuration for a linear handling system. 
         FIG. 15  shows certain details of an external return system for a handling system of  FIG. 14 . 
         FIG. 16  shows additional details of an external return system for a handling system of  FIG. 14 . 
         FIG. 17  shows movement of the output carrier in the return system of  FIG. 14 . 
         FIG. 18  shows handling of an empty carrier in the return system of  FIG. 14 . 
         FIG. 19  shows movement of the empty carrier in the return system of  FIG. 14  into a load lock position. 
         FIG. 20  shows the empty carrier lowered and evacuated and movement of the gripper in the return system of  FIG. 14 . 
         FIG. 21  shows an empty carrier receiving material as a full carrier is being emptied in the return system of  FIG. 14 . 
         FIG. 22  shows an empty carrier brought to a holding position, starting a new return cycle in the return system of  FIG. 14 . 
         FIG. 23  shows an architecture for a handling facility for a manufacturing process, with a dual-arm robotic arm system and a return system in a linear architecture. 
         FIG. 24  shows an alternative embodiment of an overall system architecture for a handling method and system of the present invention. 
         FIGS. 25A and 25B  show a comparison of the footprint of a linear system as compared to a conventional cluster system. 
         FIG. 26  shows a linear architecture deployed with oversized process modules hi a handling system in accordance with embodiments of the invention. 
         FIG. 27  shows a rear-exit architecture for a handling system in accordance with embodiments of the invention. 
         FIGS. 28A and 28B  show a variety of layout possibilities for a fabrication facility employing linear handling systems in accordance with various embodiments of the invention. 
         FIG. 29  shows an embodiment of the invention wherein a robot may include multiple drives and/or multiple controllers. 
         FIG. 30  shows transfer plane and slot valve characteristics relevant to embodiments of the invention. 
         FIG. 31  shows a tumble gripper for centering wafers. 
         FIG. 32  shows a passive sliding ramp for centering wafers. 
         FIG. 33  illustrates a fabrication facility including a mid-entry facility. 
         FIGS. 34A, 34B and 34C  illustrate a fabrication facility including a mid-entry facility from a top view. 
         FIG. 35  illustrates a fabrication facility including the placement of optical sensors for detection of robotic arm position and materials in accordance with embodiments of the invention. 
         FIGS. 36A, 36B and 36C  illustrate a fabrication facility in a cross-sectional side view showing optical beam paths and alternatives beam paths. 
         FIGS. 37A and 37B  illustrate how optical sensors can be used to determine the center of the material handled by a robotic arm. 
         FIG. 38  shows a conventional 3-axis robotic vacuum drive architecture 
         FIG. 39  shows a 3-axis robotic vacuum drive architecture in accordance with embodiments of the invention. 
         FIG. 40A  illustrates a vertically arranged load lock assembly in accordance with embodiments of the invention. 
         FIG. 40B  illustrates a vertically arranged load lock assembly at both sides of a wafer fabrication facility in accordance with embodiments of the invention. 
         FIG. 41  shows a vertically arranged load lock and vertically stacked process modules in accordance with embodiments of the invention. 
         FIG. 42  shows a linearly arranged, two-level handling architecture with vertically stacked process modules in a cross-sectional side view in accordance with embodiments of the invention. 
         FIG. 43  shows the handling layout of  FIG. 42  in a top view. 
         FIG. 44  shows an instrumented object on a robotic arm with sensors to detect proximity of the object to a target, in accordance with embodiments of the invention. 
         FIG. 45  illustrates how the movement of sensors over a target can allow the robotic arm to detect its position relative to the obstacle. 
         FIG. 46  shows how an instrumented object can use radio frequency communications in a vacuum environment to communicate position to a central controller. 
         FIG. 47  illustrates the output of a series of sensors as a function of position. 
         FIG. 48  illustrates how heating elements can be placed in a load lock for thermal treatment of objects in accordance with embodiments of the invention. 
         FIGS. 49A and 49B  show an end effector tapered in two dimensions, which reduces active vibration modes in the end effector. 
         FIGS. 50A and 50B  show how vertical tapering of robotic arm elements for a robot planar arm can be used to reduce vibration in the arm set, without significantly affecting vertical stacking height. 
         FIGS. 51A and 51B  illustrate a dual independent SCARA robotic arm. 
         FIGS. 52A and 52B  illustrate a dual dependent SCARA robotic arm. 
         FIGS. 53A and 53B  illustrate a frog-leg style robotic arm. 
         FIGS. 54A and 54B  illustrate a dual Frog-leg style robotic arm. 
         FIG. 55A  illustrates a 4-Link SCARA arm mounted on a moveable cart, as well as a 4-Link SCARA arm mounted on an inverted moveable cart. 
         FIG. 55B  illustrates a top view of  FIG. 55A . 
         FIG. 56  illustrates using a 3-Link single or dual SCARA arm robotic system to pass wafers along a substantially a linear axis. 
         FIG. 57  illustrates a 2-level vacuum handling robotic system where the top and bottom process modules are accessible by means of a vertical axis in the robotic arms. 
         FIG. 58A  shows a two level processing facility where substrates are passed along a substantially linear axis on one of the two levels. 
         FIG. 58B  illustrates a variation of  FIG. 58 a    where substrates are removed from the rear of the system. 
         FIG. 59A  shows a manufacturing facility which accommodates very large processing modules in a substantially linear axis. Service space is made available to allow for access to the interior of the process modules. 
         FIG. 59B  illustrates a more compact layout for 4 large process modules and one small process module. 
         FIGS. 60A and 60B  illustrate a dual Frog-Leg style robotic manipulator with substrates on the same side of the system. 
         FIG. 61  is a plan view of a preferred embodiment wherein a vacuum tunnel cart is configured with a process module through a transfer robot. 
         FIG. 62  is a plan view of a preferred embodiment wherein a vacuum tunnel cart is configured with a plurality of process modules through a plurality of transfer robots. 
         FIG. 63  shows the embodiment of  FIG. 62  further including process modules along both sides of the vacuum tunnel. 
         FIG. 64  is a plan view of a preferred embodiment wherein a vacuum tunnel cart is configured with a cluster process cell through a transfer robot. 
         FIG. 65  shows the embodiment of  FIG. 64  further including a plurality of cluster process cells and a plurality of transfer robots along both sides of the vacuum tunnel. 
         FIG. 66  is a plan view of a preferred embodiment wherein a vacuum tunnel cart is configured with a linear process cell through a transfer robot. 
         FIG. 67  shows the embodiment of  FIG. 66  further including a plurality of linear process cells. 
         FIG. 68  is a plan view of a preferred embodiment wherein a plurality of cluster process cells and a plurality of linear process cells are configured with a tunnel transfer cart. 
         FIG. 69  shows the embodiment of  FIG. 68  further including a plurality of transfer carts. 
         FIG. 70  is a plan view of an alternate embodiment wherein alternate cluster processing cells are combined with both tunnel transport cart systems and a linear processing group. 
         FIG. 71  is a plan view of an alternate embodiment wherein the tunnel forms a shape of an “L”. 
         FIG. 72  is a plan view of an alternate embodiment wherein the tunnel forms a shape of a “T”. 
         FIG. 73  is a plan view of an alternate embodiment wherein the tunnel forms a shape of a “U”. 
         FIG. 74  is a plan view of an alternate embodiment wherein both long duration processes and short processes are required. 
         FIG. 75  shows the embodiment of  FIG. 74  with a plurality of transport carts in the transport tunnel. 
         FIG. 76  is an alternate embodiment wherein a plurality tunnel transport cart systems are interconnected by work piece handling vacuum modules. 
         FIG. 77  shows the embodiment of  FIG. 76  wherein the tunnel transport cart system forms a complete loop. 
         FIG. 78  shows an alternate embodiment depicting a complete process group. 
         FIG. 79  shows an embodiment of a work piece buffer zone in a vacuum processing system. 
         FIG. 80  shows dual side-by-side independent transport carts in a vacuum tunnel. 
         FIG. 81  shows a side view of dual vertically opposed independent transport carts in a vacuum tunnel. 
         FIG. 82  shows an embodiment of transport cart with a robotic arm in a processing system that also includes transfer robots for work piece handling. 
         FIG. 83  shows an embodiment of dual independent transport tunnels, each with a transport cart. 
         FIG. 84  shows an embodiment of the embodiment depicted in  FIG. 83  wherein a work piece elevator is used to move a work piece from the lower tunnel to the upper tunnel. 
         FIG. 85  is an embodiment of a system wherein two types of frog-leg style robots are configured as the main work piece handling transfer robots. 
         FIG. 86  illustrates another embodiment of the systems described herein. 
         FIGS. 87-91  illustrate additional embodiments using vertical lifters and/or elevators. 
         FIG. 92  shows a system for sharing metrology or lithography hardware. 
         FIG. 93  shows a linear processing system combining a cart in a tunnel, a work piece handling vacuum module, process modules, and a multi-function module in-line and parallel to the processing flow. 
         FIG. 94  depicts a side cut away view of a bypass capable thermal adjustment module with work piece handling vacuum module access. 
         FIG. 95  is a perspective view of a configurable multi-function semiconductor vacuum module as it would be used in a semiconductor vacuum processing system. 
         FIG. 96  shows a plurality of vacuum extension tunnels in a vacuum processing system. 
         FIG. 97  depicts the buffer aligner module with four stored semiconductor work pieces. 
         FIG. 98A-98C  depicts an alignment operation of the aligner of  FIG. 97 . 
         FIG. 99A-99C  depicts an alignment of a second work piece in the aligner of  FIG. 97 . 
         FIG. 100A-100B  depicts a batch of aligned work pieces being transferred from the aligner of  FIG. 97 . 
         FIG. 101  depicts a vacuum module support pedestal in a vacuum processing system environment. 
         FIG. 102  is an exploded perspective view of a portion of a semiconductor processing system incorporating modular utility delivery modules. 
         FIG. 103  is a side view of a modular utility delivery system in an application with process chambers and elevated vacuum handing modules. 
         FIG. 104  shows a modular utility delivery modules attached to a modular vacuum processing system. 
         FIG. 105  shows a side view of an embodiment of a low particle vent system used with a semiconductor vacuum module. 
         FIG. 106  shows a batch processing system. 
         FIG. 107A-107B  shows a robotic arm for use in a batch processing system. 
         FIG. 108A-108C  shows a multi-shelf buffer for use in a batch processing system. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows equipment architectures  1000  for a variety of manufacturing equipment types. Each type of manufacturing equipment handles items, such as semiconductor wafers, between various processes, such as chemical vapor deposition processes, etching processes, and the like. As semiconductor manufacturing processes are typically extremely sensitive to contaminants, such as particulates and volatile organic compounds, the processes typically take place in a vacuum environment, in one or more process modules that are devoted to specific processes. Semiconductor wafers are moved by a handling system among the various processes to produce the end product, such as a chip. Various configurations  1000  exist for handling systems. A prevalent system is a cluster tool  1002 , where process modules are positioned radially around a central handling system, such as a robotic arm. In other embodiments, a handling system can rotate items horizontally, such as in the embodiment  1004 . An important aspect of each type of tool is the “footprint,” or the area that the equipment takes up in the semiconductor manufacturing facility. The larger the footprint, the more space required to accommodate multiple machines in a fabrication facility. Also, larger footprints typically are associated with a need for larger vacuum systems, which increase greatly in cost as they increase in size. The architecture  1004  rotates items in a “lazy susan” facility. The architecture in  1006  moves items in and out of a process module where the process modules are arranged next to each other. The architecture  1008  positions process modules in a cluster similar to  1002 , with the difference that the central robot handles two wafers side by side. Each of these systems shares many of the challenges of cluster tools, including significant swap time delays as one wafer is moved in and another out of a given process module, as well as considerable difficulty maintaining the cleanliness of the vacuum environment of a given process module, as more and more wafers are moved through the system. 
       FIG. 2  shows a conventional cluster-type architecture  2000  for handling items in a semiconductor manufacturing process. A robotic arm  2004  moves items, such as wafers, among various process modules  2002  that are positioned in a cluster around the robotic arm  2004 . An atmospheric substrate handling mini-environment chamber  2008  receives materials for handling by the equipment and holds materials once processing is complete. Note how difficult it would be to add more process modules  2002 . While one more module  2002  would potentially fit, the practical configuration is limited to five process modules  2002 . Adding a sixth module may significantly impact the serviceability of the equipment, in particular the robotic arm  2004 . 
       FIGS. 3A and 3B  show cluster tool modules, atmospheric mini-environment handling chambers, vacuum handling chambers and other components  3000  from a flexible architecture system for a vacuum based manufacturing process. Different modules can be assembled together to facilitate manufacturing of a desired process technology. For example, a given chip may require chemical vapor deposition of different chemical constituents (e.g., Titanium Nitride, Tungsten, etc.) in different process modules, as well as etching in other process modules. The sequence of the processes in the different process modules produces a unique end product. Given the increasing complexity of semiconductor components, it is often desirable to have a flexible architecture that allows the manufacturer to add more process modules. However, the cluster tools described above are space-limited; therefore, it may be impossible to add more process modules, meaning that in order to complete a more complex semiconductor wafer it may be necessary to move manufacturing to a second cluster tool. As seen in  FIG. 3A  and  FIG. 3B , cluster tools can include configurations with two  3002 , three  3004 , four  3006 , five  3008 ,  3010  or six  3012  process modules with staged vacuum isolation. Other components can be supplied in connection with the equipment. 
       FIG. 4  shows high-level components of a linear processing architecture  4000  for handling items in a manufacturing process. The architecture uses two or more stationary robots  4002  arranged in a linear fashion. The robots  4002  can be either mounted in the bottom of the system or hang down from the chamber lid or both at the same time. The linear system uses a vacuum chamber  4012  around the robot. The system could be comprised of multiple connected vacuum chambers  4012 , each with a vacuum chamber  4012  containing its own robot arranged in a linear fashion. In embodiments, a single controller could be set up to handle one or more sections of the architecture. In embodiments vacuum chambers  4012  sections are extensible; that is, a manufacturer can easily add additional sections/chambers  4012  and thus add process capacity, much more easily than with cluster architectures. Because each section uses independent robot drives  4004  and arms  4002 , the throughput may stay high when additional sections and thus robots are added. By contrast, in cluster tools, when the manufacturer adds process chambers  2002 , the system increases the load for the single robot, even if that robot is equipped with a dual arm, eventually the speed of the robot can become the limiting factor. In embodiments, systems address this problem by adding additional robot arms  4002  into a single drive. Other manufacturers have used a 4-axis robot with two completely independent arms such as a dual SCARA or dual Frog-leg robots. The linear system disclosed herein may not be limited by robot capacity, since each section  4012  contains a robot, so each section  4012  is able to transport a much larger volume of material than with cluster tools. 
     In embodiments the components of the system can be controlled by a software controller, which in embodiments may be a central controller that controls each of the components. In embodiments the components form a linkable handling system under control of the software, where the software controls each robot to hand off a material to another robot, or into a buffer for picking up by the next robot. In embodiments the software control system may recognize the addition of a new component, such as a process module or robot, when that component is plugged into the system, such as recognizing the component over a network, such as a USB, Ethernet, firewire, Bluetooth, 802.11a, 802.11b, 802.11g or other network. In such embodiments, as soon as the next robot, process module, or other component is plugged in a software scheduler for the flow of a material to be handled, such as a wafer, can be reconfigured automatically so that the materials can be routed over the new link in the system. In embodiments the software scheduler is based on a neural net, or it can be a rule-based scheduler. In embodiments process modules can make themselves known over such a network, so that the software controller knows what new process modules, robots, or other components have been connected. When a new process module is plugged into an empty facet, the system can recognize it and allow it to be scheduled into the flow of material handling. 
     In embodiments the software system may include an interface that permits the user to run a simulation of the system. The interface may allow a user to view the linking and configuration of various links, robotic arms and other components, to optimize configuration (such as by moving the flow of materials through various components, moving process modules, moving robots, or the like), and to determine what configuration to purchase from a supplier. In embodiments the interface may be a web interface. 
     The methods and system disclosed herein can use optional buffer stations  4010  between robot drives. Robots could hand off to each other directly, but that is technically more difficult to optimize, and would occupy two robots, because they would both have to be available at the same time to do a handoff, which is more restrictive than if they can deposit to a dummy location  4010  in-between them where the other robot can pick up when it is ready. The buffer  4010  also allows higher throughput, because the system does not have to wait for both robots to become available. Furthermore, the buffers  4010  may also offer a good opportunity to perform some small processing steps on the wafer such as heating, cooling, aligning, inspection, metrology, testing or cleaning. 
     In embodiments, the methods and systems disclosed herein use optional vacuum isolation valves  4006  between robot areas/segments  4012 . Each segment  4012  can be fully isolated from any other segment  4012 . If a robot handles ultra clean and sensitive materials (e.g., wafers) in its segment  4012 , then isolating that segment  4012  from the rest of the system may prevent cross-contamination from the dirtier segment  4012  to the clean segment  4012 . Also the manufacturer can now operate segments  4012  at different pressures. The manufacturer can have stepped vacuum levels where the vacuum gets better and better further into the machine. The big advantage of using vacuum isolation valves  4006  between segments  4012  may be that handling of atomically clean wafers (created after cleaning steps and needing to be transported between process modules without contamination from the environment) can be done without out-gassing from materials or wafers in other parts of the system entering the isolated chamber segment  4012 . 
     In embodiments, vacuum isolation between robots is possible, as is material buffering between robots, such as using a buffer module  4010 , a mini-process module or an inspection module  4010 . 
       FIG. 5  shows a top view of a linear processing system  4000 , such as one with a linear architecture similar to that of  FIG. 4 . 
     Different forms of robots can be used in semiconductor manufacturing equipment, whether a cluster tool or a linear processing machine such as disclosed in connection with  FIGS. 4 and 5 . 
       FIGS. 6A and 6B  show a 3-link SCARA arm  6002  and a 4-link SCARA arm  6004 . The 3-link or 4-link arms  6002 ,  6004  are driven by a robot drive. The 3-link arm  6002  is commonly used in industry. When the 3-link SCARA arm  6002  is used, the system is not optimized in that the reach-to-containment ratio is not very good. Thus, the vacuum chambers need to be bigger, and since costs rise dramatically with the size of the vacuum chamber, having a 3-link SCARA arm  6002  can increase the cost of the system. Also the overall footprint of the system becomes bigger with the 3-link SCARA arm  6002 . Moreover, the reach of a 3-link SCARA arm  6002  is less than that of a 4-link arm  6004 . In some cases a manufacturer may wish to achieve a large, deep handoff into a process module, and the 4-link arm  6004  reaches much farther beyond its containment ratio. This has advantages in some non-SEMI-standard process modules. It also has advantages when a manufacturer wants to cover large distances between segments. 
     The 4-link arm  6004  is advantageous in that it folds in a much smaller containment ratio than a 3-link SCARA arm  6002 , but it reaches a lot further than a conventional 3-link SCARA  6002  for the same containment diameter. In combination with the ability to have a second drive and second 4-link arm  6004  mounted on the top of the system, it may allow for a fast material swap in the process module. The 4-link SCARA arm  6004  may be mounted, for example, on top of a stationary drive as illustrated, or on top of a moving cart that provides the transmission of the rotary motion to actuate the arms and belts. In either case, the 4-link arm  6004 , optionally together with a second 4-link arm  6004 , may provide a compact, long-reach arm that can go through a small opening, without colliding with the edges of the opening. 
       FIG. 7  shows reach and containment characteristics of a 4-link SCARA arm  7004 . In embodiments, the 4-link SCARA arm  7004  link lengths are not constrained by the optimization of reach to containment ratio as in some other systems. Optimization of the reach to containment ratio may lead to a second arm member that is too long. When the arm reaches through a slot valve that is placed as close as practical to the minimum containment diameter, this second arm member may collide with the inside edges of the slot valve. Thus the second (and third) links may be dimensioned based on collision avoidance with a slot valve that the arm is designed to reach through. This results in very different ratios between L1, L2 and L3. The length of L2 may constrain the length of L3. An equation for optimum arm length may be a 4th power equation amenable to iterative solutions. 
       FIG. 8  shows high-level components for a robot system  8002 , including a controller  8004 , a drive/motor  8008 , an arm  8010 , an end effector  8012 , and a material to be handled  8014 . 
       FIG. 9  shows components of a dual-arm  9002  architecture for a robotic arm system for use in a handling system. One arm is mounted from the bottom  9004  and the other from the top  9008 . In embodiments both are 4-link SCARA arms. Mounting the second arm on the top is advantageous. In some other systems arms have been connected to a drive that is mounted through the top of the chamber, but the lower and upper drives are conventionally mechanically coupled. In embodiments, there is no mechanical connection between the two drives in the linear system disclosed in connection with  FIG. 4  and  FIG. 5 ; instead, the coordination of the two arms (to prevent collisions) may be done in a software system or controller. The second (top) arm  9008  may optionally be included only if necessary for throughput reasons. 
     Another feature is that only two motors, just like a conventional SCARA arm, may be needed to drive the 4-link arm. Belts in the arm may maintain parallelism. Parallelism or other coordinated movements may also be achieved, for example, using parallel bars instead of belts. Generally, the use of only two motors may provide a substantial cost advantage. At the same time, three motors may provide a functional advantage in that the last (L4) link may be independently steered, however the additional belts, bearings, connections, shafts and motor may render the system much more expensive. In addition the extra belts may add significant thickness to the arm mechanism, making it difficult to pass the arm through a (SEMI standard) slot valve. Also, the use of fewer motors generally simplifies related control software. 
     Another feature of the 4-link SCARA arm disclosed herein is that the wrist may be offset from centerline. Since the ideal system has a top-mount  9008  as well as a bottom  9004  mount 4-link arm, the vertical arrangement of the arm members may be difficult to adhere to if the manufacturer also must comply with the SEMI standards. In a nutshell, these standards specify the size and reach requirements through a slot valve  4006  into a process module. They also specify the level above centerline on which a wafer has to be carried. Many existing process modules are compliant with this standard. In systems that are non-compliant, the slot valves  4006  are of very similar shape although the opening size might be slightly different as well as the definition of the transfer plane. The SEMI standard dimensional restrictions require a very compact packaging of the arms. Using an offset wrist allows the top  9008  and bottom  9004  arms to get closer together, making it easier for them to pass through the slot valve  4006 . If the wrist is not offset, then the arms need to stay further apart vertically and wafer exchanges may take more time, because the drives need to move more in the vertical direction. The proposed design of the top arm does not require that there is a wrist offset, but a wrist offset may advantageously reduce the turn radius of the system, and allows for a better mechanical arm layout, so no interferences occur. 
       FIG. 10  shows reach and containment capabilities of a 4-link SCARA arm  6004 . 
       FIG. 11  shows interference characteristics  1102  of a 4-link SCARA arm  6004 . The wrist offset may help to fold the arm in a smaller space than would otherwise be possible. 
       FIG. 12  shows a side view of a dual-arm set of 4-link SCARA arms  6004 . Because of the packaging constraints of particularly the top arm, it may be necessary to construct an arm that has some unique features. In embodiments, one link upon retracting partially enters a cutout in another arm link. Belts can be set in duplicate, rather than a single belt, so that one belt is above  12004  and one below  12008  the cutout. One solution, which is independent of the fact that this is a 4-link arm, is to make L2 significantly lower  12002 , with a vertical gap to L1, so that L3 and L4 can fold inside. Lowering L2  12002  may allow L3 and L4 to reach the correct transfer plane and may allow a better containment ratio. Because of the transfer plane definition, the lowering of L2  12002  may be required. 
       FIG. 13  shows an embodiment in which a combination of belts and linkages is used. The transmission of motion through L1  13002  and L3  13006  may be accomplished by either a single belt or a dual belt arrangement. In contrast, the motion transmission in L2  13004  may be accomplished by a mechanical linkage (spline)  13010 . The advantage of such an arrangement may be that enclosed joints can be used which reduces the vertical dimension of the arm assembly that may allow an arm to more easily pass through a SEMI standard slot valve. 
       FIG. 14  shows an external return system for a handling system having a linear architecture  14000 . The return mechanism is optionally on the top of the linear vacuum chamber. On conventional vacuum handling systems, the return path is often through the same area as the entry path. This opens up the possibility of cross contamination, which occurs when clean wafers that are moving between process steps get contaminated by residuals entering the system from dirty wafers that are not yet cleaned. It also makes it necessary for the robot  4002  to handle materials going in as well as materials going out, and it makes it harder to control the vacuum environment. By exiting the vacuum system at the rear and moving the wafers on the top back to the front in an air tunnel  14012 , there are some significant advantages: the air return may relatively cheap to implement; the air return may free up the vacuum robots  4002  because they do not have to handle materials going out; and the air return may keep clean finished materials out of the incoming areas, thereby lowering cross-contamination risks. Employing a small load lock  14010  in the rear may add some costs, and so may the air tunnel  14012 , so in systems that are short and where vacuum levels and cross contamination are not so important, an air return may have less value, but in long systems with many integrated process steps the above-system air return could have significant benefits. The return system could also be a vacuum return, but that would be more expensive and more complicated to implement. It should be understood that while in some embodiments a load lock  14010  may be positioned at the end of a linear system, as depicted in  FIG. 14 , the load lock  14010  could be positioned elsewhere, such as in the middle of the system. In such an embodiment, a manufacturing item could enter or exit the system at such another point in the system, such as to exit the system into the air return. The advantage of a mid-system exit point may be that in case of a partial system failure, materials or wafers can be recovered. The advantage of a mid-system entry point may be that wafers can be inserted in multiple places in the system, allowing for a significantly more flexible process flow. In effect, a mid system entry or exit position behaves like two machines connected together by the mid-system position, effectively eliminating an EFEM position. It should also be understood that while the embodiment of  FIG. 14  and subsequent figures is a straight line system, the linear system could be curvilinear; that is, the system could have curves, a U- or V-shape, an S-shape, or a combination of those or any other curvilinear path, in whatever format the manufacturer desires, such as to fit the configuration of a fabrication facility. In each case the system optionally includes an entry point and an exit point that is down the line (although optionally not a straight line) from the entry point. Optionally the air return returns the item from the exit point to the entry point. Optionally the system can include more than one exit point. In each case the robotic arms described herein can assist in efficiently moving items down the line, without the problems of other linear systems.  FIG. 14A  shows an example of a U-shaped linear system. 
     Referring still to  FIG. 14 , an embodiment of the system uses a dual carrier mechanism  14008  so that wafers that are finished can quickly be returned to the front of the system, but also so that an empty carrier  14008  can be placed where a full one was just removed. In embodiments the air return will feature a carrier  14008  containing N wafers. N can be optimized depending on the throughput and cost requirements. In embodiments the air return mechanism may contain empty carriers  14008  so that when a full carrier  14018  is removed from the vacuum load lock  14010 , a new empty carrier  14008  can immediately be placed and load lock  14010  can evacuated to receive more materials. In embodiments the air return mechanism may be able to move wafers to the front of the system. At the drop-off point a vertical lift  14004  may be employed to lower the carrier to a level where the EFEM (Equipment Front End Module) robot can reach. At the load lock point(s) the vertical lift  14004  can lower to pick an empty carrier  14008  from the load lock. 
     In embodiments the air return mechanism may feature a storage area  14014  for empty carriers  14008 , probably located at the very end and behind the location of the load lock  14010 . The reason for this is that when the load lock  14010  releases a carrier  14018 , the gripper  14004  can grip the carrier  14018  and move it forward slightly. The gripper  14004  can then release the full carrier  14018 , move all the way back and retrieve an empty carrier  14008 , place it on the load lock  14010 . At this point the load lock  14010  can evacuate. The gripper  14004  can now go back to the full carrier  14018  and move it all the way to the front of the system. Once the carrier  14018  has been emptied by the EFEM, it can be returned to the very back where it waits for the next cycle. 
     It is also possible to put the lift in the load lock rather than using the vertical motion in the gripper, but that would be more costly. It would also be slightly less flexible. A manufacturer may want a vertical movement of the carrier  14018  in a few places, and putting it in the gripper  14004  would be more economical because the manufacturer then only needs one vertical mechanism. 
       FIG. 15  shows certain additional details of an external return system for a handling system of  FIG. 14 . 
       FIG. 16  shows additional details of an external return system for a handling system of  FIG. 14 . 
       FIG. 17  shows movement of the output carrier  14018  in the return tunnel  14012  of  FIG. 14 . 
       FIG. 18  shows handling of an empty carrier  14008  in the return system  14012  of  FIG. 14 . 
       FIG. 19  shows movement of the empty carrier  14008  in the return tunnel  14012  of  FIG. 14  into a load lock  14010  position. 
       FIG. 20  shows the empty carrier  14008  lowered and evacuated and movement of the gripper  14004  in the return system of  FIG. 14 . 
       FIG. 21  shows an empty carrier  14008  receiving material as a full carrier  14018  is being emptied in the return tunnel  14012  of  FIG. 14 . 
       FIG. 22  shows an empty carrier  14008  brought to a holding position, starting a new return cycle in the return tunnel  14012  of  FIG. 14 . 
       FIG. 23  shows an architecture for a handling facility for a manufacturing process, with a dual-arm robotic arm system  23002  and a return system in a linear architecture. 
       FIG. 24  shows an alternative embodiment of an overall system architecture for a handling method and system of the present invention. 
       FIG. 25  shows a comparison of the footprint of a linear system  25002  as compared to a conventional cluster system  25004 . Note that with the linear system  25002  the manufacturer can easily extend the machine with additional modules without affecting system throughput. For example, as shown in  FIG. 25A , for the vacuum section only, W=2*750+2*60+440=2060. Similarly, D=350*2+440*1.5+3*60+745/2=1913, and A=3.94 m 2 . With respect to  FIG. 25B , for the vacuum section only, W=2*750+2*60+1000=2620. Similarly, D=920+cos(30)*(500+60+750)+sin (30)*745/2=2174; accordingly, A=6.9 m 2 , which is 45% bigger. 
       FIG. 26  shows a linear architecture deployed with oversized process modules  26002  in a handling system in accordance with embodiments of the invention. 
       FIG. 27  shows a rear-exit architecture for a handling system in accordance with embodiments of the invention. 
       FIG. 28  shows a variety of layout possibilities for a fabrication facility employing linear handling systems in accordance with various embodiments of the invention. 
       FIG. 29  shows an embodiment of the invention wherein a robot  29002  may include multiple drives  29004  and/or multiple controllers  29008 . In embodiments a controller  29008  may control multiple drives  29004  as well as other peripheral devices such as slot valves, vacuum gauges, thus a robot  29002  may be a controller  29008  with multiple drives  29004  or multiple controllers  29008  with multiple drives  29004 . 
       FIG. 30  shows transfer plane  30002  and slot valve  30004  characteristics relevant to embodiments of the invention. 
       FIG. 31  shows a tumble gripper  31002  for centering wafers. The advantage of the tumble gripper  31002  over the passive centering gripper  32002  in  FIG. 32  is that there is less relative motion between the tumblers  31004  and the back-side of the wafer  31008 . The tumblers  31004  may gently nudge the wafer  31008  to be centered on the end effector, supporting it on both sides as it moves down. In certain manufacturing processes it may be desirable to center wafers  31008 , such as in a vacuum environment. The tumble gripper  31004  may allow the handling of very fragile wafers  31008 , such as when employing an end effector at the end of a robotic arm, because it supports both ends of the wafer during handling. 
       FIG. 32  shows a passively centering end effector  32002  for holding wafers  31008 . The wafer  31008  is typically slightly off-center when the end effector lifts (or the wafer  31008  is lowered). This results in the wafer  31008  sliding down the ramp and dropping into the cutout  32004 . This can result in the wafer  31008  abruptly falling or moving, which in turn can create particles. 
     The methods and systems disclosed herein offer many advantages in the handling of materials or items during manufacturing processes. Among other things, vacuum isolation between robots may be possible, as well as material buffering between robots. A manufacturer can return finished wafers over the top of the system without going through vacuum, which can be a very substantial advantage, requiring only half the necessary handling steps, eliminating cross contamination between finished and unfinished materials and remaining compatible with existing clean room designs. When a manufacturer has relatively dirty wafers entering the system, the manufacturer may want to isolate them from the rest of the machine while they are being cleaned, which is usually the first step in the process. It may be advantageous to keep finished or partially finished materials away from the cleaning portion of the machine. 
     Other advantages may be provided by the methods and systems disclosed herein. The dual arms (top mounted and bottom mounted) may work in coordinated fashion, allowing very fast material exchanges. Regardless of the exact arm design (3-link, 4-link or other), mounting an arm in the lid that is not mechanically connected to the arm in the bottom can be advantageous. The link lengths of the 4-link SCARA arm provided herein can be quite advantageous, as unlike conventional arms they are determined by the mechanical limits of slot valves and chamber radius. The 4-link SCARA arms disclosed herein are also advantageous in that they can use two motors for the links, along with a Z motor, rather than three motors plus the Z motor. 
     A linear vacuum system where materials exit in the rear may offer substantial benefits. Another implementation may be to have both the entry system and exit system installed through two opposing walls. 
     The 4-link SCARA arm disclosed herein may also allow link L3 to swing into and over link L2 for the top robot drive. This may not be easily done with the 3-link SCARA, nor with existing versions of 4-link SCARA arms, because they have the wrong link lengths. 
     The gripper for carriers and the multiple carrier locations in the linear system may also offer substantial benefits in materials handling in a linear manufacturing architecture. Including vertical movement in the gripper and/or in the rear load lock may offer benefits as well. 
     While the invention has been described in connection with certain preferred embodiments, one of ordinary skill in the art will recognize other embodiments that are encompassed herein. 
       FIG. 33  illustrates a fabrication facility including a mid-entry point  33022 . In an embodiment, the fabrication facility may include a load lock  14010  mid-stream  33002  where wafers  31008  can be taken out or entered. There can be significant advantages to such a system, including providing a processing facility that provides dual processing capabilities (e.g. connecting two machines behind each other, but only need to use one EFEM). In an embodiment, the air return system  14012  can also take new wafers  31008  to the midpoint  33022  and enter wafers  31008  there. 
       FIG. 34  illustrates several top views of a fabrication facility with mid-entry points  33002 . The figure also illustrates how the combination of a mid-entry point effectively functions to eliminate one of the EFEMs  34002 . 
       FIG. 35  illustrates a fabrication facility including a series of sensors  35002 . In many fabrication facilities such sensors  35002  are commonly used to detect whether a material  35014  is still present on a robotic arm  35018 . Such sensors  35002  may be commonly placed at each vacuum chamber  4012  entry and exit point. Such sensors  35002  may consist of a vertical optical beam, either employing an emitter and detector, or employing a combination emitter/detector and a reflector. In a vacuum handling facility, the training of robotic stations is commonly accomplished by a skilled operator who views the position of the robot arm and materials and adjusts the robot position to ensure that the material  35014  is deposited in the correct location. However, frequently these positions are very difficult to observe, and parallax and other optical problems present significant obstacles in properly training a robotic system. Hence a training procedure can consume many hours of equipment downtime. 
     Several automated training applications have been developed, but they may involve running the robotic arm into a physical obstacle such as a wall or edge. This approach has significant downsides to it: physically touching the robot to an obstacle risks damage to either the robot or the obstacle, for example many robot end effectors are constructed using ceramic materials that are brittle, but that are able to withstand very high wafer temperatures. Similarly, inside many process modules there objects that are very fragile and easily damaged. Furthermore, it may not be possible to employ these auto-training procedures with certain materials, such as a wafer  31008  present on the robot end effector. Moreover, the determination of vertical position is more difficult because upward or downward force on the arm caused by running into an obstacle is much more difficult to detect. 
     In the systems described herein, a series of sensors  35002 - 35010  may include horizontal sensors  35004 - 35010  and vertical sensors  35002 . This combination of sensors  35002 - 35010  may allow detection, for example through optical beam breaking, of either a robotic end effector, arm, or a handled object. The vertical sensor  35002  may be placed slightly outside the area of the wafer  31008  when the robotic arm  35018  is in a retracted position. The vertical sensor  35002  may also, or instead, be placed in a location such as a point  35012  within the wafer that is centered in front of the entrance opening and covered by the wafer when the robot is fully retracted. In this position the sensor may be able to tell the robotic controller that it has successfully picked up a wafer  31008  from a peripheral module. 
     Horizontal sensors  35004 - 35010  may also be advantageously employed. In vacuum cluster tools, horizontal sensors  35004 - 35010  are sometimes impractical due to the large diameter of the vacuum chamber, which may make alignment of the horizontal sensors  35004 - 35010  more complicated. In the systems described above, the chamber size may be reduced significantly, thus may make it practical to include one or more horizontal sensors  35004 - 35010 . 
       FIG. 36  illustrates other possible locations of the horizontal sensors  35004 - 35010  and vertical sensors  35002 , such as straight across the chamber ( 36002  and  36008 ) and/or through mirrors  36006  placed inside the vacuum system. 
       FIG. 37  illustrates a possible advantage of placing the sensor  35002  slightly outside the wafer  37001  radius when the robot arm is fully retracted. During a retract motion the sensor  35002  detects the leading edge of the wafer  37001  at point “a”  37002  and the trailing edge at point “b”  37004 . These results may indicate that the wafer  37001  was successfully retrieved, but by tying the sensor  35002  signal to the encoders, resolvers or other position elements present in the robotic drive, one can also calculate if the wafer  37001  is centered with respect to the end effector. The midpoint of the line segment “a-b”  37002   37004  should correspond to the center of the end effector because of the circular geometry of a wafer  37001 . If the wafer  37001  slips on the end effector, inconsistent length measurements may reveal the slippage. 
     Additionally, during a subsequent rotation and movement, a second line segment “c-d”  37008   37010  may be detected when the wafer  37001  edges pass through the sensor. Again, the midpoint between “c”  37008  and “d”  37010  should coincide with the center of the end effector, and may permit a measurement or confirmation of wafer centering. 
     The above method may allow the robot to detect the wafer  37001  as well as determine if the wafer  37001  is off-set from the expected location on the end effector. 
     The combination of horizontal and vertical sensors  35002 - 35010  may allow the system to be taught very rapidly using non-contact methods: the robotic arm and end effectors may be detected optically without the need for mechanical contact. Furthermore, the optical beams can be used during real-time wafer  37001  handling to verify that wafers  37001  are in the correct position during every wafer  37001  handling move. 
       FIG. 38  illustrates a conventional vacuum drive  38000  with two rotary axes  38020  and  38018  and a vertical (Z) axis  38004 . A bellows  38016  may allow for the vertical Z-axis  38002  motion. A thin metal cylinder  38024  affixed to the bottom of the bellows  18016  may provide a vacuum barrier between the rotor and the stator of the motors  38010  and  38014 . This arrangement may require in-vacuum placement of many components: electrical wires and feedthroughs, encoders, signal LEDs and pick-ups  38008 , bearings  38012 , and magnets  38006 . Magnets  38006 , bearings  38012 , wires and connectors, and encoders can be susceptible to residual processing gasses present in the vacuum environment. Furthermore, it may be difficult to remove gasses trapped in the bottom of the cylinder  38024 , as the gasses may have to follow a convoluted path  38022  when evacuated. 
       FIG. 39  illustrates a vacuum robot drive  39000  that may be used with the systems described herein. The rotary drive forces may be provided by two motor cartridges  39004  and  39006 . Each cartridge may have an integral encoder  39008 , bearings  39018  and magnets  39020 . Some or all of these components may be positioned outside the vacuum envelope. A concentric dual-shaft rotary seal unit  39016  may provide vacuum isolation for the rotary motion using, for example, lip-seals or ferrofluidic seals. This approach may reduce the number of components inside the vacuum system. It may also permit servicing of the motors  39004 ,  39006  and encoders  39008  without breaking vacuum, thereby increasing serviceability of the drive unit. 
       FIG. 40  shows a stacked vacuum load lock  4008 ,  40004  for entering materials into a vacuum environment. One limiting factor on bringing wafers  31008  into a vacuum system is the speed with which the load lock can be evacuated to high vacuum. If the load lock is pumped too fast, condensation may occur in the air in the load lock chamber, resulting in precipitation of nuclei on the wafer  31008  surfaces, which can result in particles and can cause defects or poor device performance. Cluster tools may employ two load locks side by side, each of which is alternately evacuated. The pumping speed of each load lock can thus be slower, resulting in improved performance of the system. With two load locks  4008   40004  in a vertical stack, the equipment footprint stays very small, but retains the benefit of slower pumping speed. In embodiments, the load lock  40004  can be added as an option. In embodiments the robotic arms  4004  and  40006  can each access either one of the two load locks  4008   40004 . In embodiments the remaining handoff module  7008  could be a single level handoff module. 
       FIG. 40B  shows another load lock layout. In this figure wafers  31008  can be entered and can exit at two levels on either side of the system, but follow a shared level in the rest of the system. 
       FIG. 41  details how the previous concept of stacked load locks  4008   40004  can be also implemented throughout a process by stacking two process modules  41006 ,  41008 . Although such modules would not be compliant with the SEMI standard, such an architecture may offer significant benefits in equipment footprint and throughput. 
       FIG. 42  shows a system with two handling levels  4008 ,  40004 ,  4010 ,  42004 : wafers may be independently transported between modules using either the top link  40006  or the bottom link  4004 . Optionally, each handling level may have two load locks to provide the advantage of reduced evacuation speed noted above. Thus a system with four input load locks, two handling levels, and optionally four output load locks, is also contemplated by description provided herein, as are systems with additional load lock and handling levels. 
       FIG. 43  shows a top view of the system of  FIG. 42 . 
       FIG. 44  depicts a special instrumented object  44014 , such as a wafer. One or more sensors  44010  may be integrated into the object  44014 , and may be able to detect environmental factors around the object  44014 . The sensors  44010  may include proximity sensors such as capacitive, optical or magnetic proximity sensors. The sensors  44010  may be connected to an amplifier/transmitter  44012 , which may use battery power to transmit radio frequency or other sensor signals, such as signals conforming to the 802.11b standard, to a receiver  44004 . 
     In many instances it may be difficult or impossible to put instrumentation on an object  44014  used to train a robot, because the wires that are needed to power and communicate to the instruments and sensors interfere with proper robotic motion or with the environment that the robot moves through. By employing a wireless connection to the object, the problem of attached wires to the object may be resolved. 
     The object  44014  can be equipped with numerous sensors of different types and in different geometrically advantageous patterns. In the present example, the sensors 1 through 6 ( 44010 ) are laid out in a radius equal to the radius of the target object  44008 . In embodiments these sensors are proximity sensors. By comparing the transient signals from the sensors  44010 , for example sensor 1 and sensor 6, it can be determined if the object  44014  is approaching a target  44008  at the correct orientation. If the target  44008  is not approached correctly, one of the two sensors  44010  may show a premature trigger. By monitoring multiple sensors  44010 , the system may determine if the object  44010  is properly centered above the target  44008  before affecting a handoff. The sensors  44010  can be arranged in any pattern according to, for example, efficiency of signal analysis or any other constraints. Radio frequency signals also advantageously operate in a vacuum environment. 
       FIG. 45  shows the system of  FIG. 44  in a side orientation illustrating the non-contact nature of orienting the instrumented object  44014  to a target  44008 . The sensors  44010  may include other sensors for measuring properties of the target  44008 , such as temperature. 
       FIG. 46  depicts radio frequency communication with one or more sensors. A radio frequency sensor signal  44016  may be transmitted to an antenna  46002  within a vacuum. Appropriate selection of wavelengths may improve signal propagation with a fully metallic vacuum enclosure. The use of sensors in wireless communication with an external receiver and controller may provide significant advantages. For example, this technique may reduce the time required for operations such as finding the center of a target, and information from the sensor(s) may be employed to provide visual feedback to an operator, or to automate certain operations using a robotic arm. Furthermore, the use of one or more sensors may permit measurements within the chamber that would otherwise require release of the vacuum to open to atmosphere and physically inspect the chamber. This may avoid costly or time consuming steps in conditioning the interior of the chamber, such as depressurization and baking (to drive out moisture or water vapor). 
       FIG. 47  illustrates the output from multiple sensors  44010  as a function of the robot movement. When the robot moves over the target  44008  the motion may result in the sensors providing information about, for example, distance to the target  44008  if the sensors are proximity sensors. The signals can be individually or collectively analyzed to determine a location for the target  44008  relative to the sensors. Location or shape may be resolved in difference directions by moving the sensor(s) in two different directions and monitoring sensor signals, without physically contacting the target  44008 . 
       FIG. 48  depicts a technique for inserting and removing wafers  48008  from a vacuum system. One or more heating elements, such as a set of heating elements  48002 ,  48004 , and  48006  may be employed, individually or in combination, to heat a chamber  4008  and a substrate material  48008  to an elevated temperature of 50° C. to 400° C. or more. This increase in starting temperature may mitigate condensation that would otherwise occur as pressure decreases in the chamber, and may allow for a more rapid pump down sequence to create a vacuum. When heated wafers  48008  are moved to the load lock  4008  by the robotic arm  4002 , they may be significantly warmer than heating units  48004 ,  48006 , such that the heating units  48004 ,  48006  may cool the wafers on contact. A heating power supply may regulate heat provided to the heating units  48004   48006  to maintain a desired temperature for the heating units and/or wafers. A suitable material selection for the heating units  48004 ,  48006  may result in the system reacting quickly to heating power changes, resulting in the possibility of different temperature settings for different conditions, for example a higher temperature setting during pump-down of the chamber  4008  and a lower setting during venting of chamber  4008 . 
     Preheating the wafers  48008  may reduce condensation and particles while reducing process time. At the same time, the wafers  48008  may be too hot when exiting the system, such that they present a safety hazard, or melt handling and support materials such as plastic. Internal temperatures of about 80 to 100° C. degrees, and external temperatures of about 50° C. degrees or less may, for example, meet these general concerns. 
       FIG. 49  illustrates a robotic end effector  49002 . The robotic end effector  49002  may be tapered so that it has a non-uniform thickness through one or more axes. For example, the robotic end effector  49002  may have a taper when viewed from the side or from the top. The taper may mitigate resonant vibrations along the effector  49002 . At the same time, a relatively narrow cross-sectional profile (when viewed from the side) may permit easier maneuvering between wafers  49006 . The side-view taper may be achieved by grinding or machining, or by a casting process of the effector  49002  with a taper. Materials such as Aluminum Silicon Carbide (AlSiC 9) may be advantageously cast into this shape to avoid subsequent machining or other finishing steps. A casting process offers the additional advantage that the wafer support materials  49004  can be cast into the mold during the casting process, thereby reducing the number of components that require physical assembly. 
     As shown in  FIG. 50 , similar techniques may be applied to robotic atm segments  50002  and  50004 . The same dampening effect may be achieved to attenuate resonant vibrations in the arm segments  50002   50004  as described above. The tapered shape may be achieved using a variety of known processes, and may allow more rapid movement and more precise control over a resulting robotic arm segment. 
       FIG. 51  shows a dual independent SCARA arm employing five motors  51014 . Each lower arm  51002  and  51008  can be independently actuated by the motors  51014 . The arms are connected at the distal end to upper arms  51004  and  51010 . The configuration gives a relatively small retract radius, but a somewhat limited extension. 
       FIG. 52  shows a dual dependent SCARA arm employing 4 motors  52010 . The links  52002  and  52004  may be common to the end effectors  52006  and  52008 . The motors  52010  may control the end effectors  52006  and  52008  in such a way that during an extension motion of the lower arm  52002 , the desired end effector, (say  52008 ) may be extended into the processing modules, whereas the inactive end effector (say  52006 ) may be pointed away from the processing module. 
       FIG. 53  shows a frog-leg style robotic arm. The a in can be used in connection with various embodiments described herein, such as to enable passing of work pieces, such as semiconductor wafers, from arm-to-arm in a series of such arms, such as to move work pieces among semiconductor process modules. 
       FIG. 54  shows a dual frog-leg arm that can be employed in a planar robotic system, such as one of the linear, arm-to-arm systems described in this disclosure. 
       FIG. 55A  illustrates a 4-Link SCARA arm as described in this disclosure mounted to a cart  55004 . Such a cart may move in a linear fashion by a guide rail or magnetic levitation track  55008  and driven by a motor  55002  internal or external to the system. The 4-Link SCARA arm has the advantage that it fold into a smaller retract radius than a 3-Link SCARA arm, while achieving a larger extension into a peripheral module such as a process module all the while avoiding a collision with the opening that the arm has to reach through. An inverted cart  55006  could be used to pass substrates over the cart  55004 . 
       FIG. 55B  shows a top view of the system described in  FIG. 55A . 
       FIG. 56  illustrates a linear system described in this disclosure using a combination of dual independent and single SCARA robotic arms. Such a system may not be as compact as a system employing a 4-Link SCARA arm robotic system. 
       FIG. 57  demonstrates a vertically stacked handling system employing a 4-Link SCARA robotic arm, where the arm can reach any and all of the peripheral process modules  5002 . By rotating the process modules in the top level  57004  by approximately 45 degrees and mounting the top level components to the bottom level chambers  57002 , the top and bottom of each of the process modules may remain exposed for service access as well as for mounting components such as pumps, electrodes, gas lines and the like. The proposed layout may allow for the combination of seven process modules  5002  in a very compact space. 
       FIG. 58A  illustrates a variation of  FIG. 57 , where the bottom level  58002  of the system consists of a plurality of robotic systems as described in this disclosure and the top level system  58004  employs process modules  5002  oriented at a 45 degree angle to the main system axis. The proposed layout allows for the combination of nine process modules  5002  in a very compact space. 
       FIG. 58B  illustrates a variation of  FIG. 58A  with the use of a rear-exit load lock facility to remove substrates such as semiconductor wafers from the system. 
       FIG. 59A  shows a linear handling system accommodating large substrate processing modules  59004  while still allowing for service access  59002 , and simultaneously still providing locations for two standard sized process module  5002 . 
       FIG. 59B  demonstrates a system layout accommodating four large process modules  59004  and a standard sized process module  5002  while still allowing service access  59002  to the interior of the process modules  5002 . 
       FIGS. 60A and 60B  show a dual frog robot with arms substantially on the same side of the robotic drive component. The lower arms  60002  support two sets of upper arms  60004  which are mechanically coupled to the motor set  54010 . 
     A variety of techniques may be used to handle and transport wafers within semiconductor manufacturing facilities such as those described above. It will be understood that, while certain processing modules, robotic components, and related systems are described above, other semiconductor processing hardware and software may be suitably employed in combination with the transport and handling systems described below. All such variations and modifications that would be clear to one of ordinary skill in the art are intended to fall within the scope of this disclosure. 
     Referring to  FIG. 61 , in a vacuum processing system, a process group  6100  may include a handling interface  6110  such as an equipment front end module connected to an exchange zone  6120 , and may be further connected to a work piece handling vacuum module  6130  that transfers work pieces from the exchange zone  6120  to a transport cart  6140  inside a transport tunnel  6150 . 
     In order to facilitate discussion of various transport/handling schemes, the combination of the transfer robot  6131  with one or more process modules  2002  is referred to herein as a process cell  6170 . It should be understood that process cells may have many configurations including conventional or unconventional process modules and/or cluster tools that perform a wide range of processes, along with associated or additional robotics for transferring wafers. This may include commercially available process modules, custom process modules, and so forth, as well as buffers, heaters, metrology stations, or any other hardware or combination of hardware that might receive wafers from or provide wafers to a wafer transportation system. Process modules  2002  and/or process cells  6170  may be disposed in various configurations, such as in clusters, aligned along the sides of a line or curve, in square or rectangular configurations, stacked vertically, or the like. Similarly, one or more robots  6131  that service process cells  6170  can be configured many ways, to accommodate different configurations of process modules, including in vertically stacked or opposing positions, in line with each other, or the like. 
     The process group  6100  may further include one or more isolation valves  6180  such as slot valves or the like that selectively isolate vacuum zones within the group  6100  and facilitate work piece interchange between vacuum zones. The isolation valves  6180  may provide control to maintain a proper vacuum environment for each work piece during one or more processing steps, while permitting intermittent movement of work pieces between vacuum zones. 
     In the embodiment of  FIG. 61 , the work piece handling vacuum modules  6130  and  6131  transfer work pieces between other components of the group  6100 , and more particularly transfer work pieces between the transport cart  6140  and various destinations. The transport cart  6140  is responsible for moving a work piece from destination to destination, such as among the work piece handling vacuum modules  6130  and  6131 . In various layouts for fabrication facilities, process modules and the like may be too far separated for direct or convenient work piece transfer using robots, such as the robots  6130 ,  6131  shown in  FIG. 61 . This may arise for a number of reasons, such as the size or shape of processing modules, the positions of entry and exit points for process modules, the number of process modules in a particular fabrication layout, and so forth. As a significant advantage, the use of one or more transport carts  6140  as an intermediate transportation system permits flexible interconnection of a wide variety of modules and other equipment into complex, multi-purpose processing facilities. 
     The transport cart  6140  may transport a work piece, such as a semiconductor wafer, to a position accessible by the work piece handling vacuum module  6130 , and may selectively transport items such as wafers or other workpieces to a process module  2002  for processing. The transport cart  6140  can be realized in many embodiments, including a magnetically levitated and/or driven cart, a cart on a railway, a cart with an arm or extending member, a cart on wheels, a cart propelled by a telescoping member, a cart propelled by an electric motor, a cart that is capable of tipping or tilting, a cart that may traverse a sloping tunnel to move a work piece or work pieces from one height to another, an inverted cart suspended from a transport track, a cart that performs processing or one of several functions on a work piece during transport, or the like. 
     The cart  6140  may be on gimbals, or suspended as a gondola, to accommodate variations in horizontal alignment of the path of the cart  6140 . Similarly, the cart may include a wafer holder (e.g., supports, shelves, grippers, or the like) that is on gimbals, or that is suspended from a wire or the like, such that the wafer holder maintains a substantially level orientation while the cart traverses an incline. Thus, in certain embodiments, the cart may traverse inclines, declines, or direct vertical paths while maintaining a wafer or other workpiece in substantially uniform, level horizontal alignment. Such a cart may have a selectively fixed horizontal alignment so that movements such as acceleration or deceleration in a horizontal plane do not cause tipping of the workpiece. In other embodiments, the cart may be permitted to tip during acceleration or deceleration in order to stabilize a position of the work piece on the cart  6140 . 
     The cart  6140  may be made of materials suitable for use in vacuum, such as materials that mitigate generation of undesirable particles or materials that have low outgassing characteristics. In an embodiment, the cart  6140  is a simple cart, without a robotic arm. As a significant advantage, using an armless cart mechanically simplifies the cart, thus saving on maintenance, repairs, and physical contamination of vacuum environments. In such embodiments, each entrance/egress from the cart path preferably includes a robot or similar device to place and retrieve workpieces on the cart. 
     In order to distinguish between various possible implementations, the following description employs the term “passive cart” to denote a cart without a robotic arm or other mechanism for loading and unloading wafers. As noted above, this configuration provides a number of advantages in terms of simplicity of design and in-vacuum implementation, and provides the additional advantage of mitigating the creation of contaminants from mechanical activity. The term “active cart” is employed herein to denote a cart that includes a robotic arm. Active carts present different advantages, in particular the improved versatility of having a robotic arm available arm at all times with the cart and a relaxation of the corresponding requirement for wafer handling hardware at each port  6180  of the tunnel  6150 . It will be understood that, while providing a useful vocabulary for distinguishing between carts with and without robots, a so-called “passive cart” may nonetheless have other mechanical or active components such as wheels, sensors, and so forth. 
     The cart  6140  may include space for a single wafer or the like. In some embodiments, the cart  6140  may include a plurality of shelves so that multiple wafers can be transported by the cart. The shelves may have a controllable height or the like in order to accommodate access to different ones of the wafers by a fixed-height robot, or the shelves may have a fixed height for use with robotic handlers having z-axis control. In still other embodiments, the cart  6104  may include a single surface having room for multiple wafers. While multi-wafer variations require an additional degree of processing control (to account for multiple possible positions of a wafer on each cart), they also provide increased flexibility and capacity to the systems described herein. In other embodiments, the cart  6140  may be adapted to carry a multi-wafer carrier or for concurrent handling and/or processing of multiple wafers. 
     The cart  6140  may provide supplemental functionality. For example, the cart  6140  may include a wafer cooling or heating system that controls wafer temperature during transport. The cart  6104  may also, or instead, include wafer center finding sensors, wafer metrology sensors, and the like. It will be appreciated that, while a range of possible supplemental functions may be supported by the cart  6104 , those functions that employ solid state sensing and processing may be preferably employed to facilitate preservation of a clean processing environment. 
     The tunnel  6150  may be of any cross-sectional shape and size suitable for accommodating the transport cart  6140  and any associated payload. In general, the tunnel  6150  will be capable of maintaining an environment similar or identical to various process cells connected thereto, such as a vacuum. The vacuum environment may be achieved, for example by providing slot valves or the like for independent vacuum isolation of each port  6180  (generally indicated in  FIG. 61  as coextensive with slot valves  6180 , although it will be understood that the slot valve identifies the mechanism by which seals are opened and closed, while the port refers to the opening through which wafers and the like may be passed). While a slot valve or slit valve is one common form of isolation device, many others are known and may be suitable employed with the systems described herein. Thus it will be understood that terms such as slot valve, slit valve isolation valve, isolation mechanism, and the like should be construed broadly to refer to any device or combination of devices suitable for isolating various chambers, process modules, buffers, and so forth within a vacuum environment, unless a narrower meaning is explicitly provided or otherwise clear from the context. 
     In some embodiments, the tunnel  6150  may maintain an intermediate environment where, for example, different process cells employ different vacuum levels, or include other gasses associated with processing. While depicted as a straight line, the tunnel  6150  may include angles, curves, and other variations in path suitable for accommodating travel of the transport cart  6140 . In addition, the tunnel  6150  may include tracks or other surfaces consistent with the propulsion system used to drive the transport cart  6140  from location to location. In some embodiments, the tunnel  6150  may include inclines or other variations that accommodate changes in height among various process cells connected thereto. All such variations that can be used with a cart  6140  to move wafers or other workpieces within a processing environment are intended to fall within the scope of this disclosure. 
       FIG. 62  shows another embodiment of a wafer processing system including a transport system. As shown, the system  6100  may include a plurality of transfer robots and process modules capable of simultaneously handling and/or processing a plurality of wafers. The system  6100  may also include a controller such as computing facility (not shown) interconnected with the transport and processing system members to schedule motion of the cart  6140  according to various processes within the system  6100 . Processing of each work piece may be controlled so that transport cart  6140  position and availability is coordinated with start and stop times of the processes within a number of process cells  6170 . The process cells  6170  may be identical or different. In various embodiments, the system  6100  may perform serial processing, parallel processing, or combinations of these to process a plurality of work pieces at one time, thereby improving utilization of the processing resources within the process cells  6170 . 
       FIG. 63  shows another embodiment of a semiconductor processing facility including a wafer transport system. As depicted in  FIG. 63 , process cells  6170  may be connected to both sides of a transport tunnel  6150 . Numerous variations in work piece processing, such as those depicted in  FIGS. 61-62  above, may be employed in combination with the configuration of  FIG. 63 . As illustrated by these figures, any number of process cells  6170  in a variety of configurations, may be readily accommodated by a transport cart  6140  interconnecting process cells  6170 . This includes greater numbers of processing cells  6170 , as well as curved, angled, multi-lane, and other cart paths. For example, cells on one side of a cart path may mirror process cells on the right side, to provide dual three-step process groups having a common tunnel  6150 , transport cart  6140 , transfer robot  6130 , exchange zone  6120  and interface module  6110 . 
       FIG. 64  illustrates a configuration that uses a work piece handling vacuum module  6131  and a plurality of process modules  2002  arranged as a cluster tool  6410 . This layout offers the compact footprint and functionality of a cluster tool, along with a cart-based transport system that can be flexibly interconnected to any number of additional process cells. 
       FIG. 65  shows another embodiment of a semiconductor processing facility including a transport system. In this system, a number of cluster tools  6410  are interconnected using a transport cart  6140  and tunnel  6150  as described generally above. It will be noted that this arrangement permits interconnection of any number of cluster tools regardless of size. As a significant advantage, this reduces the need for a dense group of cluster tools arranged around a single or multi-robot handling system. 
       FIG. 66  shows another embodiment of a semiconductor manufacturing facility using a wafer transport system. In this embodiment, a linear processing system  6610  is constructed with a plurality of process modules  2002 A- 2002 D functionally interconnected through a number of robots  6131 ,  6632 ,  6633  that employ robot-to-robot hand offs for wafer handling within the linear system  6610 . This linear system  6610  may include an interface to a transport cart  6140  which may move wafers to and from the linear system  6610  and any other process cells  6170  connected to the transport system. It will be understood that, while in the depicted embodiment, each transfer robot services two process modules  2002  and handles transfer of work pieces to another transfer robot, other linear layouts may also be employed. 
     In operation, work pieces may move into the linear process cell by manipulation with the transfer robot  6131  from transport cart  6140 . The transfer robot  6131  may either transfer the work piece to transfer robot  6632  or to one of two process modules  2002 A or  2002 B. The transfer robot  6632  may receive a work piece to be processed from the transfer robot  6631  and either transfers it to the transfer robot  6633  or to one of two process modules  2002 C or  2002 D. The transfer robot  6633  may receive a work piece to be processed from the transfer robot  6632 . Finished work pieces may be transferred to consecutive, adjacent transfer robots until passing through the transfer robot  6131  onto tunnel transport cart  6140 . In one embodiment, a load lock may be provided at one end of the linear system  6610  to permit the addition or removal of wafers at an opposing end of the linear system  6610  from the transport cart interface. 
       FIG. 67  shows a semiconductor fabrication facility including a transport system. As shown in  FIG. 67 , a number of linear systems  6610  may be interconnected using a transport cart  6140  and tunnel  6150 . As a significant advantage, a single vacuum environment for a number of different linear systems  6610  may be interconnected regardless of the layout and physical dimensions of each linear system  6610 . Additionally, longer sequences of processing, or increased throughput of work pieces for individual process cells, can readily be achieved using the cart and tunnel systems described herein. 
     In one aspect, the selection of process cells connected to the tunnel  6150  may be advantageously made to balance or control system-wide throughput. Thus, for example, process cells with relatively quick process times can be combined with a suitable number of parallel process cells providing a different process with a slower process time. In this manner, a process cell with quick process time can be more fully utilized by servicing multiple downstream or upstream process cells within a single vacuum environment. More generally, using the transport cart  6140  and tunnel  6150 , or a number of such carts and tunnels, greater design flexibility is provided for fabrication process layouts to balance load and/or improve utilization among process cells with varying process times and throughput limitations. 
       FIG. 68  shows a semiconductor fabrication facility with a transport system. As shown, a fabrication facility may include a variety of different tool and module types. For example, the facility may include plurality of cluster process cells  6410  and a plurality of linear process cells  6610 , along with a storage cell  6820  that provides a multi-wafer buffer for temporary in-vacuum storage of work pieces. As further depicted, the system may include more than one front end module using, for example, two front end modules on opposing ends of a tunnel  6150 . As will be clear from the following description, other shapes are possible, and may include T-junctions, Y-junctions, X-junctions, or any other type of interconnections, any or all of which may end at a front end module or connect to one or more additional tunnels  6150 . In this manner, large, complex layouts of interconnected processing modules may be more readily implemented. It will be further understood that individual process cells may be added or removed from such a system in order to adapt a processing facility to different process requirements. Thus, a modular and flexible fabrication layout system may be achieved. 
       FIG. 69  shows a semiconductor fabrication facility with a transport system. In the embodiment of  FIG. 69 , an isolation valve  6180  is provided within a straight length of vacuum tunnel  6150 . The isolation valve  6180  permits isolation of portions of the tunnel  6150 , and more particularly allows processes in which different vacuum environments are appropriate for different groups of process cells. In this embodiment, a second transport cart  6940  is included so that each half of the tunnel  6150  includes an independent transportation vehicle while the isolation valve  6180  is closed. It will be understood that, in certain processes, the isolation valve may remain open and both carts may service both halves of the tunnel  6150 . More generally, this illustrates the flexibility of the transportation system to accommodate complex processes using a variety of different processing tools. As depicted in  FIG. 69 , the system may also include a work piece storage elevator  6920  to provide storage for a plurality of work pieces. 
     Referring to  FIG. 70 , cluster and linear processing groups may be combined with a plurality of tunnel transport cart systems to provide a complex process group. In the embodiment of  FIG. 70 , two cluster processing cells, a first cluster processing cell  7010  at a first end of the processing group, and a second cluster processing cell  7011  at a second end of the processing group, each interconnect with tunnel transport cart  6140 ,  6140 A for transporting work pieces among the process cells. As depicted, the linear processing cell  7050  may include an access port on each end. 
     In the embodiment of  FIG. 70 , an example work piece flow may include receiving the work piece in first cluster processing cell  7010  from input interface module  6110 , processing the work piece as necessary in the cluster cell  7010 . The first tunnel transport cart  6140  may then transport the work piece to a linear processing group  7050  where it is received by the work piece handling vacuum module  6130  and processed, as required, in one or more process modules  2002 . Within the linear processing group  7050  the work piece may be transferred between adjacent transfer robots until all processing within the linear processing group  7050  is complete for the work piece, at which time the work piece is transferred to a second tunnel transport cart  6140 A for transport to a second cluster processing cell  7011 . Further processing of the work piece, as required, may be performed in the second cluster processing cell  7011  and received into an exit interface module  7020  for automated or manual retrieval. 
     It will be appreciated that the system may handle multiple wafers at one time. In some embodiments, wafers may flow uniformly from one entrance (e.g., a first front end module  7020 ) to one exit (e.g., a second front end module  6110 ). However, the depicted layout can readily accommodate wafers simultaneously traveling in the opposing direction, or wafers entering and exiting through a single one of the front end modules, or combinations of these. As noted above, this permits the deployment of fabrication facilities that significantly improve utilization of particular processing tools, and permits the implementation of numerous, different processes within a single fabrication system. 
       FIG. 71  shows a two-ended tunnel  7110  having an L-shape.  FIG. 72  shows a three-ended tunnel  7210  having a T-shape.  FIG. 73  shows a two-ended tunnel  7130  having a U-shape. It will be understood that tunnels may use any of these shapes, as well as other shapes, and combinations thereof in order to accommodate design factors ranging from floor space within a facility to the shape and size of individual pieces of equipment. As depicted by these figures, a variety of different process cell types may be connected to a tunnel as appropriate to a particular process. 
     Referring to  FIG. 74 , a transport cart  6140  may interconnect systems having different processing times. For example, the transport cart  6140  may connect a preclean process  6130  to a system  7410  with relatively long process times such as Chemical Vapor Deposition (“CVD”) and a system  7420  with relatively short process times such as Physical Vapor Deposition (“PVD”). 
     For configurations that include process steps of substantially different durations, slower processes  7410  may be supported by a relatively large number of associated tools (which may be deployed as clusters or linear groups) in order to balance throughput for the combined processing system  7400 . Thus, using the transport systems described herein, conceptual bottlenecks in complex semiconductor manufacturing processes can be addressed by simply expanding capacity around longer processes, thereby improving utilization of tools having relatively shorter processes. By way of example and not of limitation, processes having relative durations of 1 (preclean): 2 (PVD): 10 (CVD) can be supported by a facility having 2 preclean tools, 20 CVD processing tools, and 4 PVD processing tools working together in a single vacuum environment supported by a cart  6140  and tunnel  6150 . While preserving this ratio, the total number of each tool type may be expanded or contracted according to further process constraints such as the throughput capacity of front end modules or other separate systems within a fabrication facility. 
     Referring to  FIG. 75 , the configuration of  FIG. 74  alternatively may include a plurality of carts  6140  in one tunnel  6150  wherein each cart transports work pieces over a portion of the tunnel  6150 . Coordination of the carts may be employed to avoid collision of adjacent carts at a common side process cell. 
     An alternate embodiment may include a tunnel configured as a loop to allow transport carts that have reached the end process cell to continue in a loop to an input interface module to accept a new work piece for transport. The loop may be configured either as a horizontal loop or a vertical loop, or a combination of these. 
     Referring to  FIG. 76 , a plurality of tunnel transport carts may be interconnected by work piece handling vacuum modules. In the embodiment of  FIG. 76 , a transfer robot  6130  may serve as an interface between two separate tunnel transport carts  6140  and  6140 A, and may further serve as an interface to a front end module  6110  for purposes of transferring work pieces into and out of the vacuum environment. The embodiment of  FIG. 76  may accommodate substantial flexibility of use of the process cells. Each interface module may enable access to both of the tunnel transport carts, facilitating increased capacity if the process cells associated with each tunnel are the same. Alternatively, the embodiment of  FIG. 76  may allow redundancy of processes; a common interface module for different processes, or may support additional processing steps by combining the separate tunnel transport cart systems into one process group. 
       FIG. 77  shows a system  6100  wherein the transport system forms a complete loop  7710 . In this embodiment, a transport cart  6140  may move continuously in a single direction around the loop, while adding or removing work pieces at appropriate locations within the process. In addition, one or more locations may be serviced by an equipment front end module for transferring work pieces to and from the vacuum environment. As a significant advantage, this layout permits direct transfer between any two process cells connected to the system. It will be understood that any number of transport carts  6140  may share the tunnel, and having more than one transport cart  6140  increases processing options by permitting multiple inter-cell transfers at a single time. 
       FIG. 78  shows a semiconductor processing system including a transportation system. The system  7800  is a complex system including a variety of cart and processing module configurations. In particular, the system  7800  of  FIG. 78  includes four front end modules, one storage module, four independent cart transport systems, and six separate linear processing modules. By way of illustration, it will be noted that one of the linear processing modules  6110  includes two front end modules (one on each end), and intersects two tunnels for interconnection to adjacent processing systems. More generally, and as generally noted above, any arrangement of tools, clusters, and related hardware can be shared using one or more tunnels and carts as described herein. The embodiment of  FIG. 78  may allow work pieces to be removed from the vacuum environment at a number of locations (illustrated as front end modules) to undergo atmospheric processes such as inspection, chemical mechanical polishing, or electro-plating. Work pieces may also be returned to the vacuum environment as needed. A wide variation of possibilities emerges from this type of system. 
     In the configuration of  FIG. 78 , transfer robots  6130  may be used to transfer work pieces from a transport cart  6140  to a process cell  6170 , or an interface module  6110 , as well as transferring work pieces between carts  6140  on separate transport vacuum tunnels  6150 . 
     This configuration permits a work piece to be processed on one or more of the processes associated with one or more of the transport vacuum tunnels without the work piece having to be removed from the vacuum environment. Linking transport vacuum tunnels by transfer robots allows for isolation of one or more of the transport vacuum tunnels, thus permitting adjacent use of different vacuum environments and enabling independent operation of the processes associated with each of the transport vacuum tunnels. 
       FIG. 79  shows an embodiment which includes vacuum tubes  7910  located between processing modules. More generally, these vacuum tubes  7910  may be placed between any adjacent vacuum hardware to extend a vacuum environment across a physical void. The vacuum tubes  7910  may be fashioned of any suitable material including, where interior visibility is desired, glass or the like. These vacuum tubes  7910  can be intended to provide additional functionality such as described in previous paragraphs and below, and have very few design constraints except that they preferably form a vacuum seal where they physically connect to other system components, and they provide sufficient interior space for passage of wafers, workpieces, and any robotic arms or the like associated with handling same. In general, the vacuum tubes  7910  serve as a physical buffer between adjacent hardware, such as processing modules (or, as depicted, pairs of modules serviced by a single robot) in order to permit functional couplings that cannot be achieved directly due to physical dimensions of the hardware. 
       FIG. 80  shows a semiconductor processing system including a transportation system. The embodiment of  FIG. 80  includes dual side-by-side independent transport carts in a single vacuum tunnel. Carts  6140  and  6140 A may operate independently on non-interfering paths  8010  and  8011  within the tunnel  6150 . Robots  6130  may transfer a work piece among a first cart  6140 , a second cart  6140 A, and an interface  6110 . In one embodiment, the robots  8030  that service one or more of the process cells may be configured to reach across the tunnel  6150  so that workpieces may be picked from or placed to either of the carts  6140 A,  6140 B. A number of work piece handling vacuum modules may move work pieces between the carts  6140 ,  6140 A and their respective process cells. The embodiment of  FIG. 80  allows for faster transfer of work pieces among process cells than would an embodiment with dual coordinated transport carts or a single path. In another aspect, the paths  8010 ,  8011  may include exchanges or cross-overs to permit each cart  6140 ,  6140 A to switch between the paths  8010 ,  8011  for increased flexibility in material handling. One or more isolation valves may be provided to isolate various segments of the tunnel  6150 . 
       FIG. 81  shows a side view of dual vertically opposed independent transport carts in a vacuum tunnel. In the embodiment of  FIG. 81 , a tunnel  6150  encloses two transport carts  6140  running on railway or levitation systems  8130 . A robot  6130  may access work pieces through an isolation valve  6180  for loading and unloading the work pieces among an interface  7410  (such as a load-lock or equipment front end module) and the transport carts  6140 . In a similar way, transfer robots (not shown) may transfer work pieces among carts  6140  and process cells  8120 . The transfer robot  6130  may be vertically adjustable through use of a robot lift  8140  or other z-axis controller to facilitate transferring a work piece between different cart levels. 
       FIG. 82  shows an embodiment of transport cart with a robotic arm in a processing system that also includes transfer robots for work piece handling. Transfer robots  6130  and  6130 A may coordinate with a cart robot  8210  to facilitate handling of work pieces. One or more vacuum extensions  7910  may be provided to physically accommodate adjacent process cells. 
       FIG. 83  illustrates a semiconductor manufacturing system with dual independent transport tunnels  6150 . Each tunnel may include a transport cart  6140 . In the embodiment of  FIG. 83 , a transfer robot  8310  with vertical motion capabilities may transfer work pieces among the transport cart in the lower tunnel, the transport cart in the upper tunnel, and a load-lock  7410 . Similarly, transfer robots (not shown) may transfer work pieces among the upper cart  6140 , the lower cart  6140  and the process cells  8120 . 
       FIG. 84  is an alternate embodiment of the embodiment depicted in  FIG. 83  wherein a work piece elevator  8410  is used to move a work piece from the lower tunnel to the upper tunnel. Additionally, a transfer robot  6130  may be associated with each tunnel  6150  to transfer the work piece between the work piece elevator  8410  and the transport cart  6140 . Additionally a transfer robot  6130  may be required between the work piece elevator  8410  and the load-lock  7410  to facilitate transfer of work pieces between the workpiece elevator  8410  and the load-lock  7410 . 
       FIG. 85  shows an embodiment of a tunnel system using frog-leg type robots. The frog-leg type robot may be the main work piece handling transfer robot. The transfer robot  8510  may be used to transfer work pieces from the interface  6110  to the cart  6140 , and is depicted as a fully retracted frog-leg robot. The transfer robot  8520  may also be retracted and is shown in a cluster cell configuration on the right side of tunnel  6150 . Additional robots within the system may be frog-leg robots, as illustrated generally in the linear processing arrangement on the left side of the tunnel  6150 . In the linear processing group, the transfer robot  8530  may extend into a process chamber, while transfer the robot  8540  extends toward the transfer robot  8550 , which is depicted as a dual frog-leg robot partially extended toward both associated process chambers simultaneously. 
       FIG. 86  illustrates an embodiment of an integration scheme of a “bucket-brigade”  8610  linear group, a wafer transport shuttle system  8620  and traditional cluster tool systems  8630 . More generally, any combination of traditional cluster tools  8630 , linear “bucket-brigade” systems  8610  and shuttle systems  8620  is possible. In one application, short processes on the cluster tool can be combined with longer processes in the bucket brigade to improve per-tool utilization within the system. 
     While numerous arrangements of semiconductor handling and processing hardware have been described, it will be understood that numerous other variations are possible to reduce floor space usage and shorten the distance between related processing groups. For example, vacuum transport systems may be usefully deployed underneath floors, behind walls, on overhead rails, or in other locations to improve the layout of fabrication facilities, such as by clearing floor space for foot traffic or additional machinery. In general, these embodiments may employ vertical lifts in combination with robotic arms and other handling equipment when loading or transferring wafers or other work pieces among processing modules.  FIG. 87  depicts such a system including a vertical lift. 
       FIG. 87  shows a typical loading/unloading system for use in wafer fabrication. An overhead track  8702  may deliver a cart  8704  with work pieces, to a wafer Front Opening Unified Pod (FOUP) which may include a load point  8708  and an equipment front end module (EFEM)  8710 . A load lock  14010  may be employed to transfer wafers from the FOUP  8708  to one or more processing modules using, for example, the work piece handling vacuum module  6130  depicted in  FIG. 87 . A plurality of work piece handling vacuum modules supported by pedestals  10110  with intervening vacuum modules  4010  may be configured as a semiconductor vacuum processing system. Work pieces may be transferred in a cassette  8718  that the cart  8704  may lower to the FOUP  8708  using an elevator or vertical extension  8720 . 
       FIG. 88  illustrates an improved wafer handling facility in which a transport cart  6140  in a vacuum tunnel  6150  is installed beneath a factory floor. A vertical lift  8810  may be employed to move wafers, or a cassette carrying one or more wafers to the processing level. It will be understood that, while a single cart  6140  in a single tunnel  6150  is depicted, any number of tunnels  6150  and/or carts  6140  may intersect at a lifter  8810  that transfers wafers to a bottom access load lock  14010 . 
       FIG. 89  illustrates an embodiment of an overhead cart  6140  and vacuum tunnel system  6150 . This system may be used with any of the layouts described above. The configuration depicted in  FIG. 89  facilitates transferring a cart  6140  carrying one or more wafers from a tunnel  6150  to a load lock  14010 . However, in general, the lifter  8810  may be employed to move wafers and/or carts from a top access load lock (which is at a processing level) to an overhead vacuum tunnel  6150  where a cart  6140  can transport the work pieces along a transport system, such as a rail system. In one embodiment, drive elements of the lifter (not shown) may be installed below the processing level (e.g. on a floor or beneath a floor), or above the processing level. Deploying the mechanical aspects of the lifter below the processing level may advantageously reduce the number and/or size of particles that may fall on wafers being carried by the lifter. 
       FIG. 90  depicts a semiconductor vacuum processing system including two processing groups, such as a linear processing groups interconnected by a beneath-processing-level tunnel  6150 . The tunnel  6150 , which may include any of the vacuum tunnel systems described above, may be deployed, for example, beneath a factory floor. The tunnel  6150  may connect groups of processing modules separated by large distances, and may improve the handling capabilities of the interconnected system by providing, e.g., storage areas, switches, sorting systems, and so forth. Processing groups may include process chambers, load locks, work piece handling vacuum modules  6130 , vacuum modules  4010 , multifunction modules, bypass thermal adjustment modules, lithography, metrology, mid-entry load locks, vacuum tunnels extensions for extending the reach of a vacuum system, and a wide variety of semiconductor processing related functions. Processing groups may also include modules supported by a pedestal. One or more processing groups, including the tunnel  6150  and cart  6140  may be controlled by a controller, such as a computing facility executing a software program 
       FIG. 91  depicts two processing groups interconnected by an overhead tunnel network. The tunnel network  9102 , which may include any of the vacuum tunnel systems described above, may be deployed, for example, on a second floor above a factory floor or suspended from a factory ceiling. The tunnel network  9102  may connect groups of processing modules separated by large distances, and may improve the handling capabilities of the interconnected system by providing, e.g., storage areas, switches, sorting systems, and so forth. 
       FIG. 92  shows a system for sharing metrology or lithography hardware. As illustrated, the tunnel network and other module interconnection systems described herein may incorporate, e.g., shared metrology or lithography resources  9205  wherein the vacuum based cart system removes and returns a sample wafer from a flow. Generally wafers “flow” from one equipment front end module  9203  or other atmospheric interface entrance station to another equipment front end module  9204 . If an in-process inspection is desirable to check for certain process parameters, such an inspection could be performed in a location such as an inter-module buffer  9207 . In the present system there are several such interim locations where such an inspection could be performed. However, some measurement systems can be physically quite large and can be difficult to accommodate in module interconnections such as the inter-module buffer  9207  because of their size. 
     In such a situation it may be desirable to provide a vacuum cart and tunnel system as generally disclosed herein to remove one or more wafers from the flow under vacuum to a standalone metrology or lithography system  9205 . A cart  9208  may be positioned in the flow at a location  9201  between process modules to receive a wafer. It will be understood that, while a particular location is identified in  FIG. 92  as the location  9201 , any number of locations within the system  9200  may be similarly employed according to desired process flows, capabilities, physical space constraints, and so forth. Software or setup logic may determine which wafer to remove from the flow at  9201 . In other embodiments, the cart may dock with a module  9202  within the system  9200 , where a wafer handling robot may load a wafer on the cart for transport to the metrology or lithography system  9205 . 
     As depicted in  FIG. 92 , a metrology or lithography system  9205  may be shared by more than one work piece processing system. In an example, a wafer originating from the first loading system  9203  may be assessed in a metrology system  9205  that can also be accessed by wafers originating from a second system  9206 . While two linear systems are depicted, it will be understood that other arrangements of processing modules may similarly employ shared resources such as metrology or lithography systems according to the general principles described with reference to  FIG. 92 . For example, using a variety of rail configurations with, for example, curves, switches, and so forth, the system may be configured to concentrate metrology or lithography systems and/or other shared resources for any number of processing systems in a common location. Such a system could apply metrology or lithography to wafers from multiple locations and multiple systems. As described above with respect to processes having different process times, a single metrology or lithography system may be shared among numerous process cells or system to achieve high utilization of metrology or lithography resources in a semiconductor manufacturing system. 
     As noted above, the cart and work piece handling vacuum module systems described herein may be combined with simple vacuum tube extensions that may be disposed in-line with, or adjacent to work piece handling vacuum modules  6130  to facilitate greater levels of flexibility in the arrangement and interconnection of different processing hardware. Referring to  FIG. 93 , a semiconductor work piece processing system may include a cart, a tunnel, an EFEM, a plurality of work piece handling vacuum modules, various process chambers, and a vacuum extension tunnel  9304 . 
     In addition one or more link modules  9302 ,  9308  may be provided to interconnect any of the above hardware. In addition to accommodating hardware spacing (in the same manner as vacuum extensions), a module  9302 ,  9308  may provide a variety of supplemental functions associated with a semiconductor processing system. For example, a link module  9308  may provide storage, operating as a buffer in a wafer process flow. A link module  9302  may provide metrology, measurement, or testing of wafers. A link module  9308  may provide operator access to a work piece, in which case the link module  9308  may include an isolation valve and vacuum pump. A link module  9302 ,  9308  may provide thermal management, such as by cooling or heating a wafer between processes. A link module may provide buffering and/or aligning capacity for single and/or multiple wafers such as provided by the buffering aligner apparatus  9700  described below. With respect to the buffering aligner, it will be understood that this use in a link module is an example only, and that a buffering alignment module may also or instead be usefully employed at other points in a process, such as in an equipment front end module. For example, if process chambers process wafers in mini-batches of 2, 3, 4 or 5 or more wafers, then it may be efficient to employ a buffering system at an aligner to prevent the alignment time from becoming a bottleneck in a larger process. Once the proper number of wafers has been prepared in the buffer of an EFEM, an atmospheric robot can affect a batch transfer of these (aligned) wafers to a load lock. 
     A link module may provide bypass capabilities, permitting two or more wafers to cross paths between process modules. More generally, a link module  9302 ,  9308  may provide any function that can be usefully performed in a vacuum environment between processing tools, including any of those identified above as well as combinations of same. 
     As a significant advantage, such multi-function link modules can reduce the need for additional processing modules, and reduce wait times between processing modules in a variety of ways. For example, bypass capabilities alleviate the need to complete remove one wafer from a cluster or linear processing module before adding another, since conflicting paths can be resolved within the bypass module. As another example, thermal management within link modules can reduce the need to wait for heating or cooling once a wafer reaches a particular tool. Other advantages will be apparent to one of ordinary skill in the art. 
     More generally, using the systems and methods described herein, a workpiece may be processed during transport and/or wait time between process tools. This may include processing in a link module  9302 ,  9308  as described above, as well as processing on a transport cart  6150 , processing in a tunnel  6150 , processing in a buffer, processing in a load lock, or processing at any other point during wafer handling between process tools. 
       FIG. 94  shows a thermal bypass adjusting vacuum module. It is frequently desirable to heat or cool work pieces between process steps of a semiconductor manufacturing process. It may also be desirable to simultaneously allow other work pieces to pass by the work piece being heated or cooled. Since cooling or heating a work piece may take approximately 20 to 60 or more seconds, it is also advantageous to facilitate transfer of other work pieces so that the cooling or heating does not block work piece flow. A vacuum module in which work pieces can be exchanged between robots while facilitating temperature adjustment of another work may also allow temporary storage of work pieces. 
     Such a vacuum module may include an environmentally sealable enclosure to capture and thermally adjust a work piece in transition before the work piece is transferred to the next process step, while allowing coordinated pass through of other work pieces during the heating or cooling process. 
     It may be advantageous to include such a vacuum module in close proximity to a process chamber in a vacuum semiconductor processing system, such that a work piece may be heated or cooled to meet the particular needs of the process chamber for improved processing. Additionally, including and utilizing such a vacuum module can facilitate effective use of process chambers in the system by allowing a second work piece to be brought up to temperature as a first work piece is being processed. 
     Additionally, a work piece may be returned to ambient temperature immediately after it is taken from a process chamber, before it is handled by additional transfer robots, thereby eliminating any waiting time while the work piece cools before transferring another work piece to the process chamber. 
     It may also be beneficial to include a bypass thermal adjuster in combination with cart/tunnel systems in a semiconductor processing system to further facilitate flexibility, utility, process efficiency, and the like. Disclosed in this specification are examples of beneficial configurations of the bypass thermal adjuster in combination with work piece handling vacuum modules, carts  6140 , tunnels  6150 , and other process and function modules. 
     Referring to  FIG. 94 , an end effector of a work piece handling vacuum module  6130  is transferring a work piece into a thermal adjustment buffer module  9402  for purposes of thermally adjusting the work piece. 
       FIG. 94  further shows a work piece handling vacuum module  6103  placing the work piece on support clips  9404  which are mounted to an upper interior surface of a moveable enclosure, and may include fingers or the like to support the edges of a work piece centered within the enclosure. The moveable enclosure consists of two portions, an enclosure bottom  9410  and an enclosure top  9412 . When the enclosure top  9412  is lowered into contact with the bottom  9410 , a work piece supported by support clips  9404  is fully isolated from the environment outside enclosure  9408 . The bypass thermal adjuster  9402  also facilitates transferring a second work piece through the module when the moveable enclosure is closed. 
     Various embodiments of tunnel and cart systems have been described above, as well as other linking hardware such as vacuum extensions and linking modules. In general, these systems support modular use and reuse of semiconductor processing tools from different vendors, and having different processing times and other characteristics. In one aspect, such systems may be further improved through variations such as different tunnel shapes (curvilinear, L, U, S, and/or T shaped tunnels) and shapes supporting two, three, four, or more equipment front end modules. In another aspect, additional hardware may be employed to provide further flexibility in the design and use of semiconductor manufacturing systems. The following description identifies a number of additional components suitable for use with the systems described herein. 
     Referring to  FIG. 95 , a semiconductor work piece handling robot  6130  may connect through a vacuum port to a configurable vacuum module  9502 . The configurable vacuum module  9502  may include ports  9504  for utilities such as gas, water, air, and electricity used during processing. 
     The configurable vacuum module  9502  may include a removable bottom plate which may include a work piece heater for preheating a work piece before the handling robot  6130  transfers the work piece into an attached processing module. 
     The configurable vacuum module  9502  may include storage for a plurality of work pieces. As an example, work pieces may be placed by the handling robot  6130  on a rotating platform within the configurable vacuum module  9502 . The maximum number of work pieces may be determined by the size of each work piece and the size of the rotating platform. Alternatively the configurable vacuum module  9502  may include a surface adapted to support semiconductor work pieces, with the surface sufficiently large to allow a plurality of work pieces to be placed on the surface in a non-overlapping arrangement. The storage within the configurable vacuum module  9502  may be enabled by a work piece elevator with a plurality of work piece support shelves, wherein the elevator can be controlled to adjust height for selection of a particular shelf to be accessed by the handling robot  6130 . 
     The configurable vacuum module  9502  may include metrology devices for purposes of collecting metrics about the work piece. As an example, a metrology device such as an optical sensor, can be used to detect the presence of a work piece in the configurable vacuum module  9502  and initiate an automated inspection of the work piece by a machine vision system. Such metrics are useful to maintain and improve control and quality of the fabrication processes being performed on the work piece in associated process modules. 
     The configurable vacuum module  9502  may further include interface ports  9504  capable of supporting ultra high vacuum operation. The ultra high vacuum may be achieved by configurable vacuum module  9502  wherein the configurable vacuum module  9502  is constructed with materials such as stainless steel known to support an ultra high vacuum environment. Such an environment may be useful for removing trace gasses in the environment and reducing the introduction of gasses caused by outgassing of materials in the environment. 
     The configurable vacuum module  9502  may provide a load lock function for the vacuum processing environment. Such a function may be useful in work piece exchange between a user ambient environment and the vacuum processing environment by allowing work pieces supplied by a user to be introduced into the vacuum environment by sealing the work pieces in the configurable vacuum module  9502  and generating a vacuum environment around the sealed work pieces. 
     The configurable vacuum module  9502  may support fabrication processing of a work piece such as rapid thermal anneal or in-situ wafer cleaning. Rapid thermal anneal may be beneficial in a semiconductor vacuum processing environment for achieving specific changes in a semiconductor work piece such as activating dopants, and densifying deposited films. In-site wafer cleaning can be needed to remove residue or particles deposited during processing in the chambers from the wafer surfaces or edges. 
     The configurable vacuum module  9502  may also include combinations of any of the above, as well as any other capabilities suitable for use between processing tools in a semiconductor manufacturing environment. 
     In general, it is expected that the configurable vacuum module  9502  may be configured at a fabrication site through the addition or removal of hardware associated with desired functions. Thus, for example, temperature sensors and a heating element may be removed, and replaced with multiple shelves for wafer storage. Other aspects, such as construction from materials appropriate for high vacuum, may be implemented during manufacture of the module  9502 . In general, a configurable vacuum module  9502  as described herein is characterized by the removability/replaceability of module hardware, or by an adaptation to a particular process using a combination of hardware that provides multiple capabilities (e.g., heating, cooling, aligning, temperature sensing, cleaning, metrology, annealing, scanning, identifying, moving, storing, and so forth). 
     The functions described above may also be implemented directly within the cart and tunnel systems described above, either as link modules within a tunnel, or in association with a cart or tunnel, to provide various processing functions during transportation of a wafer. As described herein, combining work piece handling vacuum modules and carts/tunnels provides greater flexibility to a semiconductor processing system by facilitating the interconnection of local processing groups that are separated by a large distance, and by facilitating the interconnection of large processing systems that are in close proximity. Combining a multifunction module  9502  with a cart/tunnel system can facilitate the productive use of transport time to achieve more rapid wafer processing. 
     Referring to  FIG. 96  a vacuum extension tunnel  9602  is described in greater detail. The vacuum extension tunnel  9602 , also referred to herein as a vacuum tube or vacuum extension, can be used in a variety of positions in a semiconductor vacuum processing system to provide a continuous vacuum connection between vacuum modules. Vacuum extension tunnel  9602  may have a substantially rectangular shape, with interface ports on one or more sides. Each interface port may provide a vacuum sealable industry standard interface for connection to a variety of vacuum modules. In embodiments, an isolation valve  4006  may be connected to each interface port to provide a means of ensuring vacuum isolation between vacuum extension tunnel  9602  and a connected vacuum module. 
     As shown in  FIG. 96 , a vacuum extension tunnel  9602  provides linear extension in a semiconductor processing system, facilitating the use of varying size process chambers. As an example in  FIG. 96 , a process chamber  2002 L, which is substantially larger than process chamber  2002 R, would interfere with an equipment front end module  34002  if it were connected without using vacuum extension tunnel  9602 . An additional benefit of this use of vacuum extension tunnel  9602  is that large process chambers may be used without increasing the size of an associated robot vacuum chamber  4012  that provides wafer transport between adjoining pieces of equipment. 
     A vacuum tunnel extension  9602  can also be used with load locks  14010  to create service access between vacuum modules. Two such examples illustrated in  FIG. 96  include a service access between an upper and lower pair of process chambers, and one between the upper pair of process chambers and an equipment front end module  34002 . Service access requires a user to closely approach the process equipment and perhaps to gain direct access to work piece handling equipment. Without vacuum tunnel extension  9602 , a user could not easily approach closely enough for servicing. 
     A vacuum tunnel extension  9602  may be employed in a variety of other locations within a system. For example, a vacuum tunnel extension  9602  may be employed to connect a linear processing system, a cluster tool, a shared metrology system or an equipment front end module to a cart and tunnel transport system. A vacuum tunnel extension  9602  may facilitate forming various layout shapes of semiconductor processing systems, and may be provided in various extension lengths. 
     More generally any of the above systems may be used in combination. For example, a linear processing system including work piece transport, such as that provided by a work piece handling vacuum module combined with a transport cart  6140  may be associated with a bypass thermal adjuster. A work piece handling vacuum module may facilitate transfer of a work piece to/from the bypass thermal adjuster. A linear processing system including work piece transport, such as that provided by a work piece handling vacuum module combined with a transport cart  6140  may be associated with a wafer center finding method or system. A work piece handling vacuum module may facilitate collecting data of a work piece being handled by the work piece handling vacuum module to support the wafer center finding methods and systems. A work piece handling vacuum module may include a plurality of work piece sensors to support wafer center finding. Wafer center finding may also be performed while the work piece is being transported by the transport cart  6140 . In one embodiment, a work piece handling vacuum module, adapted to facilitate wafer center finding, may be assembled to a transport cart  6140  so that a wafer/work piece held within the work piece handling vacuum module may be subjected to a wafer finding process during transport. 
     A linear processing system including work piece transport, such as that provided by a work piece handling vacuum module combined with a transport cart  6140  may be associated with a process chamber. A work piece handling vacuum module may facilitate transfer of a work piece to/from the process chamber. As herein described, processing chambers of various types, sizes, functionality, performance, type, and the like may be combined with one or more transport carts  6140  to facilitate processing flexibility of a semiconductor processing system. A linear processing system including work piece transport, such as that provided by a work piece handling vacuum module combined with a transport cart  6140  may be associated with a load lock  10410  as herein described. In an example a work piece handling vacuum module may facilitate transfer of a work piece between the load lock and a transport cart  6140 . A linear processing system including work piece transport, such as that provided by a work piece handling vacuum module combined with a transport cart  6140  may be associated with a work piece storage and handling cassette. A work piece handling vacuum module may facilitate transfer of a work piece to/from the cassette as shown in  FIGS. 68 and 69 . A work piece handling vacuum module may transfer a work piece such as a production wafer, a test wafer, a calibration wafer, a cleaning wafer, an instrumented wafer, a wafer centering fixture, and the like to/from the work piece storage. 
     A linear processing system including work piece transport, such as that provided by a work piece handling vacuum module combined with a transport cart  6140  may be associated with an equipment front end module  6110 . A work piece handling vacuum module may facilitate transfer of a work piece to/from the equipment front end module  6110 . The work piece handling vacuum module may transfer one or more work pieces between two equipment front end modules  6110  wherein one module is an input module, and one module is an output module, or wherein one of the modules is a mid entry input/output module. A transport cart  6140  may be associated with an equipment front end module  6110  through a work piece handling vacuum module as shown in  FIG. 78 . The work piece handling vacuum module in  FIG. 78  may transfer a work piece between the equipment front end module  6110  and one of a process chamber  2002 , another work piece handling vacuum module, or a transport cart  6140 . As can be seen in  FIG. 78 , combining work piece handling vacuum modules and equipment front end modules  6110  with transport carts  6140  within vacuum tunnels  6150  can facilitate configuring arbitrarily complex or highly flexible processing systems. 
     A linear processing system including work piece transport, such as that provided by a work piece handling vacuum module combined with a transport cart  6140  may be associated with a work piece elevator. A work piece handling vacuum module may facilitate transfer of a work piece to/from the work piece elevator for transporting one or more work pieces between vertically separated work piece handling and/or processing systems. Vertically separated vacuum processing systems may include a processing level and a work piece return level that is vertically separated. The work piece return level may include a work piece transport cart or vehicle in a vacuum tunnel for transporting one or more work pieces to a different location in the vacuum processing system.  FIGS. 88-91  depict exemplary configurations of linear processing systems including work piece handling vacuum modules, transport carts  6140 , and work piece elevators, also known as lifters  8810 . 
     A linear processing system including work piece transport, such as that provided by a work piece handling vacuum module combined with a transport cart  6140  may be associated with a cluster system as shown in  FIGS. 70 and 86 . A work piece handling vacuum module may facilitate transfer of a work piece to/from the cluster system. A work piece handling vacuum module may facilitate transfer of a work piece between a linear processing system including a transport cart  6140 , and a cluster processing cell. The work piece handling vacuum module may transfer the work piece to/from an aspect of the cluster system such as a work piece handling robot, a load lock, a buffer, and the like. The work piece handling vacuum module may transfer a work piece through a vacuum extension tunnel  9602  to/from the aspect of the cluster processing system. 
     The work piece handling vacuum module may be modularly connected to the cluster system so that the work piece handling vacuum module may provide handling of work pieces while the cluster processing system may provide processing of semiconductor work pieces. The work piece handling vacuum module may be connected to the cluster system through a buffer module, such as a multifunction module, a passive single work piece buffer, a passive multi work piece buffer, a thermal bypass adapter, a buffering aligner  9700 , and the like. The buffer module may provide a temporary storage facility for work pieces being transferred between the work piece handling vacuum module and the cluster system. A robot controller of the cluster system may access or deposit a work piece in the buffer module for the work piece handling vacuum module to transfer. A plurality of cluster systems may be connected to one work piece handling vacuum module so that the work piece handling vacuum module facilitates transfer from one cluster system to another. Such a configuration may include a load lock  1401  and/or equipment front end module  6110  for exchange of the work pieces with an operator. The work piece handling vacuum module may further include facilities for determining a center of a work piece being handled by the work piece handling vacuum module so that the work piece can be transferred to the cluster system centered accurately to a center reference of the cluster system. 
     A linear processing system including work piece transport, such as that provided by a work piece handling vacuum module combined with a transport cart  6140  may be associated with other work piece handling vacuum modules. A work piece handling vacuum module may facilitate transfer of a work piece to/from the other work piece handling vacuum module. 
     A linear processing system including work piece transport, such as that provided by a work piece handling vacuum module combined with a transport cart  6140  may be associated with a buffer. A work piece handling vacuum module may facilitate transfer of a work piece to/from the buffer. The buffer may facilitate holding work pieces queued to be processed. The buffer may further facilitate reducing bottlenecks associated with robotic work piece handlers, differences in processing time, delays associated with vacuum environment changes, and the like. 
     A linear processing system including work piece transport, such as that provided by a work piece handling vacuum module combined with a transport cart  6140  may be associated with a controller. The controller may direct the work piece handling vacuum module to facilitate transfer of a work piece from a first section of a semiconductor processing system to a second section of the system. Transfer from the first to second section of the system may be accomplished by using a transport cart  6140 . A section may include one or more of a buffer, a buffering aligner  9700 , another work piece handling vacuum module, a cluster system, a work piece storage, a work piece elevator, an equipment front end module, a load lock, a process chamber, a vacuum tunnel extension, a module including a low particle vent, a module including a pedestal, a module including a modular utility supply facility, a bypass thermal adjuster, a multifunction module, a robot (e.g. single arm, dual arm, dual end effector, frog leg, and the like), variously shaped process systems, and the like. 
     Referring to  FIGS. 97-100 , work pieces may be temporarily stored in buffer modules. A buffer module may, for example, be placed between two transfer robot modules to facilitate handling and throughput, or between a tunnel  6150  and a robot for similar reasons. The buffer module may be accessible from multiple of sides and/or by multiple robots. The buffer module may have the capability to hold a plurality of semiconductor work pieces. In embodiments, the buffer may also be capable of performing alignment of the semiconductor work pieces that are placed into the buffer. Such a buffer may be referred to as a buffer aligner module  9700 , an example of which is depicted in  FIG. 97 . The buffer aligner module  9700  may include a buffer work piece holder  9702 , an aligner platform  9704 , and an aligner vision system  9708 . The buffer work piece holder  9702  may hold multiple semiconductor work pieces  9710 ,  9712 ,  9714 , and  9718  at one time, which may be vertically stacked or otherwise arranged within the holder  9702 . In embodiments, the aligner platform  9704  may be capable of holding a single semiconductor work piece and rotating or translating the work piece to a desired alignment position as determined by an aligner controller. The controller may initiate a rotation or translation once the semiconductor work piece has been placed on the aligner platform  9704 , and determine a stopping position based on signals provided by the aligner vision system  9708 . 
     The aligner vision system  9708  may sense a notch or other marking on the semiconductor work piece, and the controller may use the notch to determine a correct alignment of the work piece, such as by stopping rotation of the work piece when the notch is in a particular location. The aligner vision system  9708  may also employ optical character recognition (OCR) capabilities or other image processing techniques to read and record information presented on the semiconductor work piece, which may include alignment marks as well as textual information relating to the work piece. The controller may also, or instead, provide close-loop sense and control for the alignment of semiconductor work piece placed on the buffer aligner module  9700 . 
       FIG. 98A  shows a transfer robot  9802  transferring a semiconductor work piece  9720  onto the aligner platform  9704  of the buffer aligner module  9700  utilizing a single work piece end-effector.  FIG. 98B  shows the aligner platform  9704  rotating a semiconductor work piece to be aligned  9720 . While the aligner platform  9704  is rotating, the aligner vision system  9708  may sense the position of the work piece  9720  through some physical indicator, such as a notch, a marking, or the like. The controller may stop rotation in response to an appropriate signal from the aligner vision system  9708  indicating that the work piece is properly aligned. When aligned, the semiconductor work piece  9720  may be transferred into the buffer work piece holder  9702  as shown in  FIG. 98C . 
       FIG. 99A  shows a transfer robot  9802  transferring a second semiconductor work piece  9720  onto the aligner platform  9704 . Note that the first buffered work piece  9710  has been previously stored in the top slot of the buffer work piece holder.  FIG. 99B  shows the second semiconductor work piece  9720  being aligned.  FIG. 99C  shows the two aligned semiconductor work pieces stored as a first  9710  and second buffered work piece  9712 . Finally,  FIG. 100A  shows all aligned and stored work pieces  9710 ,  9712 ,  9714 , and  9718 , being transferred from the buffer aligner module  9700  by a transfer robot  9802  utilizing a batch end-effector  10002  to simultaneously move the work pieces  9710 ,  9712 ,  9714 , and  9718 .  FIG. 100B  shows the transfer robot  9802  moving the batch of semiconductor work pieces  9710 ,  9712 ,  9714 , and  9718  to their destination with the batch end-effector  10002 . 
     A linear processing system including work piece transport, such as that provided by a work piece handling vacuum module combined with a transport cart  6140  may be associated with a buffering aligner  9700 . A work piece handling vacuum module may facilitate transfer of a work piece to/from the buffering aligner  9700  such as to/from an equipment front end module, load lock, and other semiconductor fabrication system modules, handlers, and processors. A buffering aligner  9700  may be beneficially combined with other elements of a linear processing system to improve throughput. In an example, a buffering aligner  9700  may be combined with a transport cart  6140  system that provides transport of a plurality of aligned wafers in a vacuum environment. A buffering aligner can be employed when a process chamber requires delivery of multiple wafers at the same time, in which case buffering at the alignment can significantly increase the system throughput by allowing the system to align wafers in the background during processing and effecting a batch transfer to the process module or load lock. 
       FIG. 101  shows a number of modular linkable handling modules  6130 . Each linkable module  6130  may be supported by a pedestal  10110 . The pedestal  10110  may form a unitary support structure for a vacuum robotic handler and any associated hardware, including, for example, the linking modules described above. The pedestal  10110  may be generally cylindrical in form with adequate external diameter to physically support robotics and other hardware, and adequate internal diameter to permit passage of robotic drives, electricity, and other utilities. 
     A robot drive mechanism  10120  may be integrated within the pedestal  10110 . Integration of the robot drive mechanism  10120  into the support structure may advantageously eliminate the need for separate conduits or encasements to house the robot drive mechanism  10120 . An access port  10125  within the pedestal  10110  may provide user access to various components of the robot drive  10120  such as motors, amplifiers, seals etc., so that these components can be removed as individual units for servicing and the like. 
     The pedestal configuration depicted in  FIG. 101  provides additional advantages. By raising the modular linkable handling modules  6130  substantially above floor level while preserving significant unused space between the floor and the modules  6130 , the pedestal  10110  offers physical pathways for process chamber utilities such as water, gas, compressed air, and electricity, which may be routed below the modular linkable handling modules  6130  and alongside the pedestals  10110 . Thus, even without planning for utility access, a simple arrangement of pedestal-based modules in close proximity ensures adequate access for wires, tubes, pipes, and other utility carriers. In order to achieve this result, the pedestal  10110  preferably has top projection surface area (i.e., a shape when viewed from the top) that is completely within the top projection surface area of the module  6130  supported above. Thus space is afforded all the way around the pedestal. 
     The pedestal  10110  may include a rolling base  10130  (with adjustable stand-offs for relatively permanent installation) on which additional controls, or equipment  10140  may be included. The rolling base  10130  further facilitates integration of vacuum modules  6130  into a modular vacuum processing and handling system. 
     A linear processing system including work piece transport, such as that provided by a work piece handling vacuum module combined with a transport cart  6140  may be associated with a pedestal. A work piece handling vacuum module may be modularly mounted to the pedestal so that the pedestal may provide at least support for the work piece handling vacuum module. The pedestal may further support drive mechanism that provide rotation and other motion of a robotic work piece handler in the work piece handling vacuum module. The pedestal may be integrated with the work piece handling vacuum module as herein described. The pedestal may further facilitate supporting a work piece handling vacuum module in a position that facilitates transferring a work piece to a transport cart  6140  in a tunnel  6150 . 
     Linking modules  10149  between the vacuum modules  6130  may provide any of the functions or tools described herein with reference to, for example, the configurable vacuum modules  9502  described above. This includes auxiliary equipment  10150  such as a vacuum pump, machine vision inspection tool, heating element, or the like, as well as various machine utilities (gas, electric, water, etc.) which may be removably and replaceably affixed in a vacuum or other functional seal to an opening  10155  in the linking module  10149 . 
       FIG. 102  shows how unused space (created by a pedestal support structure) around a link module may be coherently allocated among various utilities that might be required to support a semiconductor manufacturing process. Referring to  FIG. 102 , a portion of a modular vacuum processing system is shown in an exploded view. The portion of the system shown in  FIG. 102  includes a work piece handling and processing system  10200  which may include one or more linkable vacuum modules  6130 . The linkable modules  6130  may be interconnected to each other or to another module such as an inspection module  4010 , a vacuum extension, or any other vacuum component. As depicted, each linkable module  6130  is mounted on a pedestal  10130  which is in turn mounted on base  10230 . 
     Processing tools can connect to the work piece handling system  10200  at any one of the ports of one of the linkable modules  6130 . By applying industry standards for utility hookup type and position in a process chamber, the position of the utility hookups outside the volume of the linking modules may be substantially predetermined based on the position of the linkable module(s)  6130 . Due to the pedestal configuration, however, it is also possible to allocate the void space around each pedestal to ensure a buffer zone  10240 ,  10250 ,  10260  around the linking modules that affords substantially arbitrary routing of utilities throughout an installation using the linkable modules. The handling system  10200  enables a user to take advantage of modular utility delivery components  10240 ,  10250 , and  10260  when preparing to install process chambers. 
     The buffer zones  10240 ,  10250 , and  10260  facilitate delivery of utilities such as gas, water, and electricity to any process chambers connected to the linkable modules  6130 . These buffer zones  10240 ,  10250 , and  10260  may specifically accommodate positioning requirements of industry standards, and may also accommodate any industry standard requirements for capacity, interfacing, cleanliness, delivery pressure, and the like (without, of course, requiring conformity to these standards within the buffer zones). 
     Conceptually, the buffer zones  10240 ,  10250 , and  10260  may have a structural frame which supports a plurality of conduits  10270  adequate for delivery of the corresponding utilities. Each conduit  10270  may be constructed with appropriate materials selected to meet the specific requirements for delivery of a specific utility, and may be arranged within the buffer zones in any preferred pattern. Additionally, each conduit device port hookup  10280 , may be arrayed in a predetermined pattern (e.g. meeting industry standards for utility hookup position) to facilitate connections outside the buffer zones while ensuring alignment of utility conduits from module to module within the buffer zones. 
     Device port hookups  10280  may be selected for each utility type. For example, a hookup for water may provide reliable interconnect that can withstand water pressure, temperature, and flow rate requirements, while a hookup for electricity may provide a reliable interconnect or conduit that meets electrical impedance, safety, and current capacity requirements. In embodiments, the position of the device port hookups  10280  within the buffer zones may be mechanically identified and/or adjustable (e.g. by means of a flexible conduit). 
     In an embodiments, a physical device such as a foam mold or other structural frame containing hookups  10280  and conduits for various utilities in each buffer zone  10240 ,  10250 , and  10260  may be provided as a kit, which may allow for a variety of configurations to meet installation needs such as height, width, position of conduit, position of device hookups, and frame mounting within the constraints of the corresponding standard(s). 
     In embodiments, the buffer zones  10240 ,  10250 ,  10260  may be fully customized to meet a specific user installation and operational needs. In such an embodiment the user may provide specifications covering aspects of the system such as height, width, position of conduit, position of device hookups, mounting method, and optional aspects such as enclosure, and base to a manufacturer. 
     In embodiments, the buffer zones  10240 ,  10250 , and  10260  may be arranged with one or more of the conduits  10270  in predetermined patterns forming one or more standard layers for utilities, and one or more customizable layers. The standard layers for example, may be for water and electricity, while the customizable layers may be for gas. The standard layers may additionally incorporate predetermined conduits for water electrical wiring. 
     As shown in  FIG. 103 , the overall size of the buffer zones  10240 ,  10250 , and  10260  may be predetermined to facilitate integration with process chambers  2002  and the handling system  10200 . As described above, and as depicted in  FIG. 103 , the buffer zones may have a volume defined in at least one dimension by the volume of the associated linkable module  6130 . 
     In embodiments with differently shaped process chambers, such as a chamber that is wider in the isolation valve connection area than in the utility components connection area, the width of the buffer zones  10240  and  10260  may be different than the embodiment shown in  FIG. 103 . Alternatively, the device port hookups  10280  may be expandable in length to accommodate differently shaped process chambers. 
     The embodiment shown in  FIG. 103  allows buffer zones  10240 ,  10250 , and  10260  to be installed under a linkable module and, for example the inspection module  4010 , thereby reducing the foot print of the combined handling system  10200  while ensuring routing capability for utilities. 
       FIG. 104  shows a number of linkable modules using utility conduits adapted to the buffer zones described above. As depicted, utility delivery components  10404 ,  10406 ,  10408  are attached to the base  10230  of each linkable module. Each one of the utility deliver components may include conduits, interconnects, and connection ports conforming to any appropriate standards as generally described above. 
     In embodiments, the utility delivery components  10404 ,  10406 ,  10408  may include sensors for sensing aspects of each utility (e.g., fluid flow, gas flow, temperature, pressure, etc.) and may include a means of displaying the sensed aspects or transmitting sensor data to a controller or other data acquisition system. Sensors and associated displays may be useful for installation, setup, troubleshooting, monitoring, and so forth. For example, a modular utility delivery component  10404  delivering water may include a water pressure sensor, a water flow rate sensor, and/or a water temperature sensor, while a display may display the corresponding physical data. Other sensors for display or monitoring may include gas pressure, type, flow rate, electricity voltage, and current. Additionally, the sensors may transmit an externally detectable signal which may be monitored by a utility control computer system. 
     A linear processing system including work piece transport, such as that provided by a work piece handling vacuum module combined with a transport cart  6140  may be associated with a modular utility delivery component  10240  that may supply utilities such as air, water, gas, and electricity to a sections of a semiconductor processing system through modular connection. Groups of vacuum modules that are being provided utilities though the modular utility delivery component, such as process chambers  2002 , multifunction modules  9702 , bypass thermal adjusters  9402 , work piece handling vacuum modules, one or more load locks  14010 , wafer storage, and the like may be combined with a transport cart  6140  to facilitate transport of one or more work pieces between distal groups. Referring to  FIG. 67 , linear processing groups  6610  may be locally configured with modular utility delivery components  10240 ,  10250 ,  10260 , while transport cart  6140  provides work piece transport from one group  6610  to another. 
       FIG. 105  shows a low particle vent system. The system  10500  transfers work pieces to an from a vacuum processing environment, and may include work pieces  10510  loaded and ready to be processed in a semiconductor processing facility once a proper vacuum environment is created within the system  10500 . The system  10500  further includes an adapted gas line  10520  connected to a gas line valve  10530 , a particle filter  10540 , and a shock wave baffle  10550 . 
     In general operation, the system  10500  seals in work pieces with a door  10501  that may be opened and closed using any of a variety of techniques known to one or ordinary skill in the art to isolate the interior  10502  from an exterior environment. In operation, the system opens and closes the door  10501  to the chamber  10502 , opens the gas valve  10530  to supply gas to an interior  10502  of the system  10500 , closes the gas valve  10530 , and then evacuates the interior  10502  to form a vacuum for the work pieces  10510 . Unloading the work pieces  10510  may be accomplished in a similar way except that the system  10500  begins with a vacuum environment and is pressurized by the gas flowing through the open gas line valve  10530  and the adapted gas line  10520 . 
     Once the work pieces  10510  are placed in the interior  10502 , venting and pumping may be performed. During this process, the particle filter  10540 , configured in-line with the adapted gas line  10520  or across the opening of the chamber interior  10502 , filters large particles being transported by the gas. In addition, the baffle  10550  and the adapted gas line  10520  combine to absorb the supersonic shock waves that result from releasing a vacuum seal for the interior  10502 , thereby preventing or mitigating disruption of particles within the interior  10502 . 
     The gas line, typically a cylindrical shaped tube for passing gas from the valve  10530  to the module, is adapted by modifying its shape to facilitate absorbing the supersonic shock wave. In one embodiment, the adapted gas line  10520  may be shaped similar to a firearm silencer, in that it may have inner wall surfaces that are angled relative to the normal line of travel of the gas. More generally, the gas line may include any irregular interior surfaces, preferably normal to a center axis of the gas line. Such surfaces disperse, cancel, and or absorb the energy of the supersonic shock wave (e.g., from releasing a vacuum seal). 
     To further reduce the impact of the supersonic shock wave, the baffle  10550  obstructs travel of any remaining shock wave and protects the work pieces  10510  from perturbations that might otherwise carry particle contamination. The baffle  10550  may be positioned to reflect incident portions of the supersonic shock wave, canceling some of its energy, resulting in a substantially reduced shock wave impacting surfaces throughout the interior which may have particles. The baffle  10550  may be larger than the opening, as large as the opening, or smaller than the opening, and may be generally displaced toward the interior of the chamber from the opening. In one embodiment, the baffle  10550  may be moveable, so that it may be selectively positioned to obstruct shockwaves or admit passage of workpieces. 
     A low particle vent system as described above may be deployed at any location within any of the above systems where a vacuum seal might be released or created. 
     Many of the above systems such as the multi-function modules, batch storage, and batch end effectors may be employed in combination with the highly modular systems described herein to preserve floor space and decrease processing time, particularly for processes that are complex, or for installations that are intended to accommodate several different processes within a single vacuum environment. A number of batch processing concepts, and in particular uses of a batch aligner, are now described in greater detail. 
       FIG. 106  shows a system  10600  including a number of batch processing modules  10602  that can process a number of wafers at one time. Each module  10602  may, for example, process 2, 3, 4, or more wafers simultaneously. The system  10600  may also include a batch load lock  10604 , an in vacuum batch buffer  10606 , a buffering aligner  10608 , one or more vacuum robot arms  10610 , an atmospheric robot arm  10612  and one or more front opening unified pods  10614 . Each of the foregoing components may be adapted for batch processing of wafers. 
     The front opening unified pods  10614  may store wafers in groups, such as four. While a four wafer system is provided for purposes of illustration, it will be understood that the system  10600  may also, or instead, be configured to accommodate groups of 2, 3, 4, 5, 6, or more wafers, or combinations of these, and all such groupings may be considered batches as that term is used herein. 
     An in-atmosphere robot  10612  may operate to retrieve groups of wafers from the FOUPs  10614  which generally manage atmospheric handling of wafers for processing in the system  10600 . The robot  10612  may travel on a track, cart or other mechanism to access the FOUP&#39;s  10614 , the load lock  10604 , and the buffering aligner  10608 . The robot may include a batch end effector for simultaneously handling a batch of wafers (or other workpieces. The robot  10612  may also, or instead, include dual arms or the like so that a first arm can pick and place between the FOUPs  10614  and the batch aligner  10608  while the other arm provides a batch end effector for batch transfers of the aligned wafers in the buffer  10608  to the batch load lock  10604  and from the load lock  10604  back to the FOUPs  10614 . 
     The buffering aligner  10608  may accommodate a corresponding number of wafers (e.g., four) that are physically aligned during the buffering process. It will be understood that while a single buffering aligner is shown, a number of buffering aligners may be arranged around the in-atmosphere robot, or may be vertically stacked, in order to accommodate groups of batches for processing. It will also be understood that the buffering aligner  10608  may employ any active or passive techniques, or combinations of these, known to one of skill in the art to concurrently align two or more wafers for subsequent batch handling. 
     As a significant advantage, an aligned batch of wafers can be processed more quickly in batch form downstream. Thus, for example, an aligned batch of wafers can be transferred to the batch load lock  10604  by the robot  10612  in a manner that preserves alignment for transfer to the in vacuum robot  10610 , which may include a dual arm and/or dual end effectors for batch handling of wafers within the vacuum. Further, the in-vacuum batch buffer  10606  may accommodate batches of wafers using, e.g., shelves or the like to preserve alignment during in vacuum buffering and/or hand off between robots. The batch buffer  10606  may, of course, provide cooling, temperature control storage, or any of the other functions described above that might be useful between processing modules in a semiconductor manufacturing process. 
       FIG. 107  shows a robotic arm useful with the batch processing system of  FIG. 106 .  FIG. 107A  shows a cross sectional view of the robot  10700  while  FIG. 107B  shows a perspective drawing. In general, a robot  10700  may include a first robotic arm  10702  having a single end effector  10704  and a second robotic arm  10706  having a dual or other batch end effector  10708 . 
     Using this robotic arm configuration, the single end effector  10704  may be employed for individual picks and placements of wafers within modules while the dual end effector  10708  may be employed for batch transfers between processing modules via, e.g., batch buffers  10606 , robot-to-robot hand offs, or any other suitable batch processing technique. 
     It will be appreciated that numerous variations to this batch technique are possible. For example, the batch end effector may include two blades, three blades, or any other number of blades (or other suitable wafer supports) suitable for use in a batch process. At the same time, each robotic arm  10702 ,  10706  may be a multi-link SCARA arm, frog leg arm, or any other type of robot described herein. In addition, depending on particular deployments of manufacturing processes, the two arms may be fully independent, or partially or selectively dependent. All such variations are intended to fall within the scope of this disclosure. In addition to variations in batch size and robotic arm configurations, it will be understood that any number of batch processing modules may be employed. In addition, it may be efficient or useful under certain circumstances to have one or more non-batch or single wafer process modules incorporated into a system where process times are suitably proportional to provide acceptable utilization of the single and batch process modules in cooperation. 
       FIG. 108  illustrates how multiple transfer planes may be usefully employed to conserve floor space in a batch processing system.  FIG. 108A  shows a linking module including multiple transfer planes to accommodate single or multiple access to wafers within the linking module. Slot valves or the like are provided to isolate the linking module.  FIG. 108B  shows an alternative configuration in which multiple shelves are positioned between robots without isolation. In this configuration, the shelves may, for example, be positioned above the robots to permit a full range of robotic motion that might otherwise cause a collision between a robotic arm and wafers on the shelves. This configuration nonetheless provides batch processing and or multiple wafer buffering between robots.  FIG. 108C  shows a top view of the embodiment of  FIG. 108B . As visible in  FIG. 108C , the small adapter with shelves between robots in  FIG. 108B  permits relatively close positioning of two robots without requiring direct robot-to-robot handoffs. Instead each wafer or group of wafers can be transferred to the elevated shelves for subsequent retrieval by an adjacent robot. As a significant advantage, this layout reduces the footprint of two adjacent robots while reducing or eliminating the extra complexity of coordinating direct robot-to-robot handoffs. 
     Having thus described several illustrative embodiments, it is to be appreciated that various alterations, modifications, and improvements will readily occur to those skilled in the art. Such alterations, modifications, and improvements are intended to form a part of this disclosure, and are intended to be within the spirit and scope of this disclosure. While some examples presented herein involve specific combinations of functions or structural elements, it should be understood that those functions and elements may be combined in other ways according to the present invention to accomplish the same or different objectives. In particular, acts, elements, and features discussed in connection with one embodiment are not intended to be excluded from similar or other roles in other embodiments. Accordingly, the foregoing description and attached drawings are by way of example only, and are not intended to be limiting. 
     The elements depicted in flow charts and block diagrams throughout the figures imply logical boundaries between the elements. However, according to software or hardware engineering practices, the depicted elements and the functions thereof may be implemented as parts of a monolithic software structure, as standalone software modules, or as modules that employ external routines, code, services, and so forth, or any combination of these, and all such implementations are within the scope of the present disclosure. Thus, while the foregoing drawings and description set forth functional aspects of the disclosed systems, no particular arrangement of software for implementing these functional aspects should be inferred from these descriptions unless explicitly stated or otherwise clear from the context. 
     Similarly, it will be appreciated that the various steps identified and described above may be varied, and that the order of steps may be adapted to particular applications of the techniques disclosed herein. All such variations and modifications are intended to fall within the scope of this disclosure. As such, the depiction and/or description of an order for various steps should not be understood to require a particular order of execution for those steps, unless required by a particular application, or explicitly stated or otherwise clear from the context. 
     The methods or processes described above, and steps thereof, may be realized in hardware, software, or any combination of these suitable for a particular application. The hardware may include a general-purpose computer and/or dedicated computing device. The processes may be realized in one or more microprocessors, microcontrollers, embedded microcontrollers, programmable digital signal processors or other programmable device, along with internal and/or external memory. The processes may also, or instead, be embodied in an application specific integrated circuit, a programmable gate array, programmable array logic, or any other device or combination of devices that may be configured to process electronic signals. It will further be appreciated that one or more of the processes may be realized as computer executable code created using a structured programming language such as C, an object oriented programming language such as C++, or any other high-level or low-level programming language (including assembly languages, hardware description languages, and database programming languages and technologies) that may be stored, compiled or interpreted to run on one of the above devices, as well as heterogeneous combinations of processors, processor architectures, or combinations of different hardware and software. 
     Thus, in one aspect, each method described above and combinations thereof may be embodied in computer executable code that, when executing on one or more computing devices, performs the steps thereof. In another aspect, the methods may be embodied in systems that perform the steps thereof, and may be distributed across devices in a number of ways, or all of the functionality may be integrated into a dedicated, standalone device or other hardware. In another aspect, means for performing the steps associated with the processes described above may include any of the hardware and/or software described above. All such permutations and combinations are intended to fall within the scope of the present disclosure. 
     While the invention has been disclosed in connection with the preferred embodiments shown and described in detail, various modifications and improvements thereon will become readily apparent to those skilled in the art. Accordingly, the spirit and scope of the present invention is not to be limited by the foregoing examples, but is to be understood in the broadest sense allowable by law. 
     All documents referenced herein are hereby incorporated by reference.