Abstract:
In some aspects, a method is provided for mapping contents of a substrate carrier. The method includes (1) moving a carrier to a sensor; and (2) determining, with the sensor, a presence or an absence of a substrate in the carrier based upon a position of a substrate clamp in the carrier. Numerous other aspects are provided.

Description:
[0001]    The present application claims priority from U.S. Provisional Patent Application Ser. No. 60/870,691, filed Dec. 19, 2006, which is hereby incorporated by reference herein in its entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates generally to semiconductor device manufacturing, and more particularly to methods and apparatus for sensing substrates in carriers. 
       BACKGROUND 
       [0003]    A typical semiconductor fabrication facility includes a plurality of processing systems (“tools”) in which a sequence of process steps is performed on a workpiece (a silicon substrate, a glass plate, etc.). These steps may include polishing, deposition, etching, photolithography, heat treatment, and so forth. In general, these processes are performed at various locations within the fabrication facility, and it is accordingly necessary that substrates be transported within the facility from one processing location to another. 
         [0004]    It is conventional to transport substrates from one processing location to another within substrate carriers such as sealed pods, cassettes, containers and so forth. It is also conventional to employ automated substrate carrier transport devices, such as automatic guided vehicles, overhead transport systems, substrate carrier handling robots, etc., to move substrate carriers from location to location within the fabrication facility or to transfer substrate carriers from or to a substrate carrier transport device. 
         [0005]    In a typical automated substrate handling system, a substrate carrier is transported to a loadport where an end effector (e.g., of a robotic arm) may load substrates into or remove substrates from the carrier. A conventional loadport must open the carrier door in order to sense the presence of a substrate in the carrier. Opening a carrier door takes time, and also potentially exposes the interior of the carrier to contaminants. Accordingly, it is desirable to have methods and apparatus for sensing the presence of a substrate in a carrier at a loadport without the need for opening the carrier door. 
       SUMMARY OF THE INVENTION 
       [0006]    In a first aspect of the invention, a method is provided for mapping contents of a substrate carrier. The method includes (1) moving a carrier to a sensor; and (2) determining, with the sensor, a presence or an absence of a substrate in the carrier based upon a position of a substrate clamp in the carrier. 
         [0007]    In a second aspect of the invention, a substrate carrier is provided that includes (1) a slot adapted to support a substrate; and (2) a substrate clamping structure adapted to hold the substrate within the slot and adapted to displace from a first position to a second position when the substrate is placed in the slot, wherein at least one of the first and second positions is detectable while the substrate carrier is closed. 
         [0008]    In a third aspect of the invention, an apparatus is provided that includes (1) a loadport; and (2) a substrate carrier having (a) a slot adapted to support a substrate; and (b) a substrate clamping structure adapted to hold the substrate within the slot and adapted to displace from a first position to a second position when the substrate is placed in the slot. At least one of the first and second positions is detectable when the substrate carrier is coupled to the loadport and while the substrate carrier is closed. 
         [0009]    In a fourth aspect of the invention, an apparatus is provided that includes (1) a substrate carrier having a body with one or more channels that do not increase a height of the carrier; (2) a loadport having a door opening mechanism with one or more protrusions adapted to fit within the one or more channels of the substrate carrier; and (3) an optical sensor coupled to one or more of the protrusions of the door opening mechanism, the optical sensor adapted to detect a presence or absence of a substrate in the substrate carrier when the substrate carrier is coupled to the loadport. Numerous other aspects are provided. 
         [0010]    Other features and aspects of the present invention will become more fully apparent from the following detailed description, the appended claims and the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1A  is a schematic front view of a substrate carrier provided in accordance with an embodiment of the invention. 
           [0012]      FIG. 1B  schematically illustrates a door opening mechanism of a loadport including a through beam sensor, in accordance with an embodiment of the invention and suitable for coupling with the substrate carrier of  FIG. 1A . 
           [0013]      FIGS. 1C-E  are schematic top views of a substrate carrier docking at a loadport in accordance with the present invention. 
           [0014]      FIG. 1F  is a schematic top view of a substrate carrier including a substrate clamp with a flag used for detecting the presence of a substrate in the carrier, in accordance with an embodiment of the invention. 
           [0015]      FIG. 2  is a schematic top view of a substrate carrier including an electrical circuit to indicate the presence of a substrate in the carrier, in accordance with another embodiment of the invention. 
           [0016]      FIG. 3  is a schematic top view of a substrate carrier including a substrate clamp with a permanent magnet for activating an electrical circuit to indicate the presence of a substrate in the carrier, in accordance with a further embodiment of the invention. 
           [0017]      FIG. 4A  is a perspective view, and  FIGS. 4B and 4C  are side views, of systems including a substrate carrier and a loadport, in accordance with still other embodiments of the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0018]    Embodiments of the present invention provide methods and apparatus for detecting the presence of substrates in a substrate carrier, without the need for opening the carrier. In some embodiments, placement of a substrate in the carrier causes movement of one or more flags, where each flag is associated with a specific clamp for holding a substrate in a specific slot of the carrier. The position of a particular flag therefore indicates the presence of a substrate in the carrier at the location associated therewith. Such position may be detected in various ways without opening the carrier, as detailed below. 
         [0019]    According to a first embodiment of the invention ( FIGS. 1A-1F ), the presence of a substrate in a carrier is sensed by interrupting a light beam transmitted through the carrier. In some embodiments, the source and detector for the light beam are both outside the carrier, so that a substrate in the carrier can be detected without the carrier being opened. 
         [0020]    According to a second embodiment of the invention ( FIG. 2 ), movement of a flag of a substrate clamp causes an electrical circuit to be completed which includes a conductive path inside the carrier. The presence of a substrate in a carrier can therefore be detected when the carrier arrives at a loadport, without the carrier being opened. 
         [0021]    According to a third embodiment of the invention ( FIG. 3 ), movement of a flag of a substrate clamp causes a magnetically-actuated switch to close and thereby complete an electrical circuit including a conductive path inside the carrier. The presence of a substrate in a carrier can therefore be detected when the carrier arrives at a loadport, without the carrier being opened. 
         [0022]    According to additional embodiments of the invention ( FIGS. 4A-4C ), a carrier and loadport together form a system for detecting the presence of a substrate inside the carrier without opening the carrier. The system may be configured to detect a substrate in accordance with an interrupted optical path or a completed electrical circuit. 
         [0023]      FIGS. 1A-1B  schematically illustrate a first embodiment of the invention.  FIG. 1A  is a front view of a substrate carrier  101  (that is, the substrate carrier as viewed from a loadport when the carrier is moved to the loadport for loading or unloading a substrate) provided in accordance with the present invention.  FIG. 1B  is a front view of a door opening mechanism  102  of a loadport (not shown) provided in accordance with the present invention. The door opening mechanism  102  includes a supporting member  107  that is adapted to contact and support the door of the substrate carrier  101  when the carrier  101  is brought to the loadport for a load/unload operation. In some embodiments, the carrier  101  has channels  103  formed therein that are sized and positioned to mate with source and sensor assemblies  105   a ,  105   b  respectively, mounted or otherwise formed in or coupled to the supporting member  107  as shown in  FIG. 1B . 
         [0024]    As shown schematically in  FIG. 1B , light beams  109  produced by sources (e.g. LEDs or other light sources not separately shown) in sensor assemblies  105   a  are detected by sensors  111  mounted in sensor assemblies  105   b . The carrier  101  (or at least window portions  103   a  thereof) is made of a material transparent to light beams  109 . The window portions  103   a  may be formed of plastic or any other suitable material. 
         [0025]      FIGS. 1C-E  are schematic top views of the substrate carrier  101  docking at a loadport  106  in accordance with the present invention. As shown in  FIGS. 1B-E , sensor assemblies  105   a ,  105   b  project from the door opening mechanism  107  via protrusions or mounting features  108  so that, when carrier  101  is transported to loadport  106  and positioned adjacent the loadport  106  for a substrate load/unload operation, sensor assemblies  105   a ,  105   b  extend over a region of the carrier  101  adjacent to the door  115  of the carrier  101 , and light beams  109  are directed through the carrier  101 . In some embodiments, if a substrate  110  is absent from the carrier  101 , a light beam  109  will travel through the carrier  101  and be detected at a sensor  111  ( FIG. 1B ). If a substrate  110  is present in carrier  101 , the substrate  110 , or a flag  113   a  associated with a clamp  113  which holds the substrate  110  in a slot  116  of the carrier  101 , will interrupt beam  109  and thereby cause sensor  111  to produce a signal indicating the presence of the substrate  110 . In other embodiments, the presence of the substrate  110  in the carrier  101  will cause the substrate  110  and/or the associated clamp  113  holding the substrate  110  to allow the light beam  109  to travel through the carrier  101 . As shown in  FIGS. 1C-1E , in some embodiments, the door opening mechanism  107  may contact the carrier door  115 , support the door  115  and then separate from the remainder of the carrier  101  with the door  115  to allow access into the carrier  101 . Substrate presence and/or position may be determined before, during and/or after the door  115  is opened and/or removed. The carrier  101 , door opening mechanism  107  or both may move. 
         [0026]      FIG. 1F  is a schematic top view of carrier  101  with a substrate  110  loaded therein in accordance with the present invention. A substrate clamp  113 , located near the carrier door  115 , holds the substrate  110  in the slot  116 . In some embodiments, substrate clamp  113  incorporates a flag  113   a  which interrupts a beam  109  when a substrate is held by the clamp  113 . In other embodiments, the flag  113   a  only interrupts the light beam  109  when a substrate is not in the carrier  101 . Flag  113   a  may be an appendage of the substrate clamp mechanism, as shown in  FIG. 1F . Alternatively, the flag  113   a  may be formed separately and connected to the clamp  113  by a mechanical linkage, or be mechanically separate from the clamp  113  but be configured to move when a substrate is loaded into the carrier slot  116 . 
         [0027]    It should be noted that carrier  101  may be designed to hold a plurality of substrates, and thus contain a plurality of clamps with corresponding flags. In some embodiments, the positions of these flags are staggered with respect to each other, so that any given flag blocks a respective beam from reaching a particular sensor (or pattern of sensors) or allows a respective beam to reach a particular sensor when a substrate is loaded in the clamp  113  connected to that flag  113   a . Accordingly, the pattern of interrupted or transmitted beams indicates not only the presence of substrates in the carrier  101 , but also which slots in the carrier  101  are occupied by substrates. 
         [0028]    In another embodiment, shown schematically in  FIG. 2 , each substrate clamp  113  is provided with an electrical circuit  201  for sensing the presence of a substrate held by the clamp  113 . A portion of clamp  113  (e.g., flag  113   a ) includes an electrical contact  203 . In some embodiments, when a substrate is loaded in the carrier  101  and held by the clamp  113 , the clamp  113  is caused to move so that contacts  203 ,  205  are closed, thereby completing a conductive path between points  207  and  209  on the carrier door  115  or any other suitable location on the carrier  101 . (For the sake of clarity, contacts  203 ,  205  are shown just before being closed by the loading of the substrate in the clamp.) In other embodiments, the contacts  203 ,  205  may open when a substrate is held by clamp  113 . 
         [0029]    Suitable electrical contacts are provided on the loadport (e.g., on supporting member  107 , not shown in  FIG. 2 ), to mate with contact points  207 ,  209 . When the carrier  101  is brought up to and contacts supporting member  107  of the loadport, a complete circuit is formed if contacts  203 ,  205  are closed. A flow (or lack) of current in circuit  201  then signals the presence of a substrate in a slot of the carrier  101  associated with the clamp  113 . In some embodiments, a multi-substrate carrier having multiple substrate slots may have a clamp and/or flag for each slot, with contact points  207 ,  209  corresponding to each respective clamp  113 . Accordingly, the flow (or lack) of current through a particular set of contacts from the carrier door  115  to a loadport (not shown) indicates the presence of a substrate loaded in a particular slot of a multi-substrate carrier, so that the presence and location of substrate(s) in the carrier  101  can be detected without opening the carrier door  115 . 
         [0030]    In the preceding embodiment, physical movement of the clamp  113  causes electrical contacts  203 ,  205  to directly open or close. In another embodiment, shown schematically in  FIG. 3 , electrical circuit  301  is activated using a permanent magnet  303  associated with a portion of clamp  113 . For example, when a substrate  110  is loaded in a slot of the carrier  101  and held by clamp  113 , the resulting movement of clamp  113  brings magnet  303  close enough to magnet  305  so that magnetic attraction causes magnet  305  to move in the direction of arrow  307 . Magnet  305  is connected by a suitable mechanical linkage to electrical contact  309 ; such that movement of magnet  305  in direction  307  causes contacts  309 ,  311  to close, forming a conductive path between points  313  and  315  on the carrier door  115  (or another suitable location on the carrier  101 ). It will be appreciated that magnet  305  and contacts  309 ,  311  together form a magnetically actuated electrical switch, which may have a variety of possible configurations. In some embodiments, the presence of a substrate in a carrier slot may cause contacts  309 ,  311  to separate. Magnetic repulsion may also be used to open or close the contacts  309 ,  311 . 
         [0031]    As in the previous embodiment, suitable electrical contacts are provided at a loadport (e.g. on supporting member  107 , not shown in  FIG. 3 ) to mate with contact points  313 ,  315 . When the carrier  101  is brought up to and contacts supporting member  107  of the loadport, a complete circuit is formed if contacts  309 ,  311  are closed. A flow of current in circuit  301  then signals the presence (or absence) of a substrate in the carrier  101 . In some embodiments, a multi-substrate carrier having multiple substrate slots may have a clamp and/or flag for each slot, with contact points  313 ,  315  corresponding to each respective clamp  113 . Accordingly, the flow (or lack) of current through a particular set of contacts from the carrier door  115  to a loadport (not shown) indicates the presence of a substrate loaded in a particular slot of a multi-substrate carrier, so that the presence and location of substrate(s) in the carrier  101  can be detected without opening the carrier door  115 . 
         [0032]      FIGS. 4A-4C  illustrate systems for detecting the presence of a substrate inside a carrier without opening the carrier in accordance with the present invention; these systems include the carrier  101  and loadport  401 .  FIG. 4A  is a perspective view showing carrier  101  being moved toward door opening mechanism  403  for opening the door  115  of the substrate carrier  101 . In some embodiments, the substrate carrier  101  is supported using blade receivers  405   a ,  405   b  and an overhead transfer flange  407  (thus allowing substrate carriers to be stacked with a high packing density). The door opening mechanism  403  includes the supporting member  107  that is adapted to contact and support the door  115  of the substrate carrier  101 . During a substrate load/unload operation, the supporting member  107  moves the carrier door  115  to an open position (e.g. by pivoting the door below the remainder of the substrate carrier  101  in some embodiments, although other configurations may be used). A linear actuator or other actuator  409  (e.g., a pneumatic, motor driven, hydraulic, etc., actuator) may be employed to dock/undock the substrate carrier  101  relative to the door opening mechanism  403 . 
         [0033]      FIG. 4B  shows a side view of an exemplary embodiment of the system of  FIG. 4A , showing a cross-section of the supporting member  107  of the loadport  401 .  FIG. 4B  schematically illustrates a system in which an electro-optical circuit  411  at the loadport  401  is configured to indicate the presence of a substrate inside carrier  101  without door  115  being opened. In some embodiments, extensions  402  hold sensor assemblies  105   a ,  105   b  at the upper and lower portions of the supporting member  107 . The sensor assemblies  105   a ,  105   b  include beam sources and detectors  413 ,  415  (or vice versa), forming an interruptible optical path  416  inside at least a portion of the carrier  101 . When the carrier  101  is docked at the loadport  401  as shown in  FIG. 4B , the optical path  416  is interrupted in accordance with displacement of a flag and/or clamp (described previously) of the carrier  101  indicating the presence or absence of a substrate in a particular slot of the carrier  101 . 
         [0034]      FIG. 4C  shows another exemplary side view of the system of  FIG. 4A .  FIG. 4C  schematically illustrates a system embodying the invention in which an electrical circuit  421  is configured to signal the presence of a substrate inside carrier  101  without door  115  being opened. Inside the carrier  101 , electrical contacts  423 ,  425  are closed in accordance with displacement of a flag and/or clamp (as previously described) associated with a slot of the carrier  101 . The closing of contacts  423 ,  425  causes a conductive path to be formed between contacts  427  and  429  of the carrier door  115 . When the carrier  101  is docked at the loadport  401 , contacts  427 ,  429  of carrier  101  meet contacts  431 ,  433  respectively of the supporting member  107 , indicating either a substrate is present in or absent from a particular slot in the carrier. In some embodiments, movement of the contacts  423 ,  425  may be controlled mechanically and/or magnetically (as previously described). 
         [0035]    In any of the above embodiments, the contents of a substrate carrier may be determined and/or a map of which slots of a substrate carrier include substrates may be determined (e.g., carrier contents may be mapped). In some embodiments, the channels  103  are formed in the carrier  101  so as not to increase a height of the carrier  101  (e.g., allowing a greater stacking density). 
         [0036]    The foregoing description discloses only exemplary embodiments of the invention. Modifications of the above disclosed apparatus and methods which fall within the scope of the invention will be readily apparent to those of ordinary skill in the art. For example, fewer or more sensors may be used and/or other sensor locations may be used. Also, various arrangements of electrical contacts and/or magnetically actuated contacts may be employed. Accordingly, while the present invention has been disclosed in connection with exemplary embodiments thereof, it should be understood that other embodiments may fall within the spirit and scope of the invention, as defined by the following claims.