DETAILED DESCRIPTION

[0036] Previously incorporated, U.S. patent application serial No. 60/407,451, filed Aug. 31, 2002, entitled “System for Transporting Semiconductor Wafer Carriers” (Attorney Docket No. 6900), discloses a substrate carrier transport system that includes a conveyor for substrate carriers that is intended to be constantly in motion during operation of the fabrication facility which it serves. The constantly moving conveyor is intended to facilitate transportation of substrates within the fabrication facility so as to reduce the total “dwell” time of each substrate in the fabrication facility; thereby reducing WIP, and cutting capital and manufacturing costs. To operate a fabrication facility in this manner, methods and apparatus should be provided for unloading substrate carriers from the conveyor, and for loading substrate carriers onto the conveyor, while the conveyor is in motion.

[0037] In accordance with at least one aspect of the invention, a substrate carrier handler at a substrate loading station includes a horizontal guide that is moveable vertically along parallel vertical guides, and an end effector that is moveable horizontally along the horizontal guide. To unload a substrate carrier from a moving conveyor that transfers substrate carriers (a “substrate carrier conveyor”) and that passes by the substrate loading station, the end effector is moved along the horizontal guide at a velocity that substantially matches the velocity of the substrate carrier as it is being transported by the substrate carrier conveyor (e.g., by substantially matching substrate carrier speed in a horizontal direction). In addition, the end effector may be maintained in a position adjacent the substrate carrier as the substrate carrier is being transported. The end effector thus may substantially match a position of the substrate carrier while substantially matching a velocity of the substrate carrier. Likewise, conveyor position and/or velocity may be substantially matched.

[0038] While the end effector substantially matches the substrate carrier's velocity (and/or position), the end effector is raised, by moving the horizontal guide upwardly along the vertical guides, so that the end effector contacts the substrate carrier and disengages the substrate carrier from the substrate carrier conveyor. A substrate carrier similarly may be loaded onto the moving substrate carrier conveyor by substantially matching end effector and conveyor velocities (and/or positions) during loading. In at least one embodiment of the invention, such substrate carrier handoffs between the end effector and substrate carrier conveyor are performed at a substantially zero velocity and/or acceleration between the end effector and the substrate carrier. Numerous other aspects of the invention are provided, as described further below.

[0039] FIG. 1 is a top plan view showing a conventional loading and storing apparatus 111 in position for storing substrate carriers adjacent a conventional processing tool 113 . A factory interface (FI) 115 is shown positioned between the loading and storage apparatus 111 and the processing tool 113 . The loading and storage apparatus 111 is positioned adjacent a first side of a clean room wall 117 and the factory interface 115 is positioned adjacent a second side of the clean room wall 117 . The factory interface 115 includes an FI robot 119 that may move horizontally along a track (not shown) that is parallel to the clean room wall 117 and may extract a substrate (not shown) from one or more substrate carriers 120 present at the loading and storage apparatus 111 . The FI robot 119 may transport the substrate to a load lock chamber 121 of the processing tool 113 .

[0040] The load lock chambers 121 shown in FIG. 1 are coupled to a transfer chamber 123 of the processing tool 113 . Also coupled to the transfer chamber 123 are processing chambers 125 and auxiliary processing chambers 127 . Each of the processing chambers 125 and auxiliary processing chambers 127 may be arranged to perform a conventional semiconductor device fabrication process such as oxidation, thin film deposition, etching, heat treatment, degassing, cool down, etc. A substrate handling robot 129 is disposed within the transfer chamber 123 to transfer substrates, such as substrate 131 , among the processing chambers 125 , 127 and the load lock chambers 121 .

[0041] The loading and storage apparatus 111 includes one or more substrate carrier storage shelves 133 for storing substrate carriers before or after the substrates contained in the substrate carriers are processed by the processing tool 113 . The loading and storage apparatus 111 also includes one or more docking stations (which are not shown but may be, for example, below the storage shelves 133 ). A substrate carrier may be docked at a docking station for extraction of substrates therefrom by the FI robot 119 . Also included in the loading and storage apparatus 111 is a factory load location 135 , at which a substrate carrier transport device, such as an automatic guided vehicle (AGV), may deposit or pick up a substrate carrier.

[0042] The loading and storage apparatus 111 further includes a substrate carrier handler 137 which is adapted to move substrate carriers among the factory load location 135 , the storage shelves 133 and the docking stations.

[0043] In line with the above-noted goal of facilitating transport of substrates within a fabrication facility, it may be desirable to transport substrate carriers to and from a substrate loading station such as the loading and storage apparatus 111 by means of a substrate carrier conveyor that is constantly in motion (e.g., to reduce dwell time and thus work in progress and manufacturing costs). Consequently, in accordance with the present invention, an inventive substrate loading station is provided that can unload substrate carriers from a substrate carrier conveyor, and that can load substrate carriers onto the substrate carrier conveyor, while the substrate carrier conveyor is moving.

[0044] An embodiment of the invention will now be described with reference to FIGS. 2 A- 6 E. FIG. 2A is a front elevational view of a substrate loading station 201 provided in accordance with the invention. Although not shown in FIG. 2 A, it should be understood that the inventive substrate loading station 201 may be associated with a processing tool and/or factory interface of the kind described in connection with FIG. 1 .

[0045] The substrate loading station 201 may include one or more load ports or similar locations where substrates or substrate carriers are placed for transfer to and/or from a processing tool (e.g., one or more docking stations 203 , although transfer locations that do not employ docking/undocking movement may be employed). In the particular embodiment shown in FIG. 2 A, the substrate loading station 201 includes a total of eight docking stations 203 , arranged in two columns 205 of four docking stations each. Other numbers of columns and/or docking stations may be employed. Each docking station 203 is adapted to support and/or dock a substrate carrier 207 at the docking station 203 and to allow a substrate (not shown) to be extracted from the substrate carrier 207 at the docking station 203 and transferred to a processing tool such as the processing tool 113 of FIG. 1 (e.g., by a factory interface robot, such as the factory interface robot 119 of FIG. 1 ). In one embodiment of the invention, the substrate carriers 207 are single substrate carriers. “Single substrate carrier” will be understood to mean a substrate carrier shaped and sized to contain only one substrate at a time. Substrate carriers that hold more than one substrate also may be employed (e.g., 25 or any other number). (Alternatively, one or more docking stations 203 may be adapted to directly support a substrate without a substrate carrier). Each docking station 203 may be configured, for example, as described in previously incorporated U.S. patent application serial No. 60/407,337, filed Aug. 31, 2002 and titled “Wafer Loading Station with Docking Grippers at Docking Stations” (Attorney Docket No. 7099). Other docking station configurations may be employed.

[0046] Each docking station 203 may include a port 209 through which a substrate may be transferred to the factory interface (e.g., factory interface 115 in FIG. 1 ). Adjacent each port 209 is a docking gripper 211 which is adapted to suspend a substrate carrier 207 and to move the suspended substrate carrier between a docked and undocked position. A moveable stage or other support (not shown) alternatively may be employed to support (e.g., from below or otherwise) and/or dock/undock each substrate carrier 207 at each docking station 203 . Each port 209 may also include a substrate carrier opener 213 which, in one aspect, is adapted to employ docking movement of a substrate carrier 207 to open the substrate carrier 207 as it moves from an undocked position to a docked position as described in previously incorporated, U.S. patent application serial No. 60/407,339, filed Aug. 31, 2002, entitled “METHOD AND APPARATUS FOR USING WAFER CARRIER MOVEMENT TO ACTUATE WAFER CARRIER DOOR OPENING/CLOSING” (Attorney Docket No. 6976). Each substrate carrier 207 may have, for example, the carrier door latching and/or substrate clamping features disclosed in previously incorporated, U.S. patent application serial No. 60/407,340, filed Aug. 31, 2002, entitled “WAFER CARRIER HAVING DOOR LATCHING AND WAFER CLAMPING MECHANISMS” (Attorney Docket No. 7156). Other substrate carrier opener, door latching, and/or substrate clamping configurations may be employed.

[0047] The substrate loading station 201 also includes a substrate carrier handler 215 which operates in accordance with an aspect of the invention. In one or more embodiments of the invention, the substrate carrier handler 215 includes a pair of vertical guides 217 , 219 and a horizontal guide 221 which is mounted for vertical movement on the vertical guides 217 , 219 . A belt drive or a lead screw and an associated motor or motors (which are not shown) or other suitable mechanism is provided to drive the horizontal guide 221 for vertical movement along the vertical guides 217 , 219 . A support 223 is mounted on the horizontal guide 221 for horizontal movement along the horizontal guide 221 . A belt drive or lead screw, and associated motor or motors (which are not shown) or other suitable mechanism is provided to move the support 223 horizontally along the horizontal guide 221 .

[0048] In at least one embodiment of the invention, the vertical guides 217 , 219 may each comprise an integrated guide/driving mechanism such as Part No. 1140-260-10, 1768 mm available from Bosch, Inc. Likewise, the horizontal guide 221 may comprise an integrated guide/driving mechanism such as Part No. 1140-260-10, 1468 mm also available from Bosch, Inc. Other guide/driving mechanism systems may be employed.

[0049] An end effector 225 is mounted on the support 223 . The end effector 225 may be, for example, in the form of a horizontally-oriented platform 227 adapted to support a substrate carrier (e.g., one of the substrate carriers 207 ). In at least one embodiment, the platform 227 may have kinematic pins or other kinematic positioning features 229 . (Although only two kinematic features 229 are shown in FIG. 2 A, other numbers of kinematic pins or features such as three or more may be provided on the platform 227 .) The kinematic features 229 may cooperate with concave or otherwise shaped features (not shown in FIG. 2A ) on the bottom of the substrate carrier 207 to guide the substrate carrier 207 into correct (positive) positioning on the platform 227 . In at least one embodiment of the invention, the end effector 225 may comprise, for example, an end effector capable of changing the orientation of a substrate carrier from vertical to horizontal and vice versa as described in previously incorporated, U.S. patent application serial No. 60/407,452, filed Aug. 31, 2002 and titled “End Effector Having Mechanism For Reorienting A Wafer Carrier Between Vertical And Horizontal Orientations” (Attorney Docket No. 7097). Any other suitable end effector also may be employed.

[0050] A continuously or otherwise moving conveyor, schematically represented by an arrow 231 , is positioned above the substrate loading station 201 and the substrate carrier handler 215 . The conveyor 231 is adapted to transport substrate carriers such as the substrate carriers 207 to and from the substrate loading station 201 . In one embodiment of the invention, the continuously moving conveyor 231 may be implemented as a ribbon of stainless steel or similar material as described in previously incorporated U.S. patent application serial No. 60/443,087, filed Jan. 27, 2003 (Attorney Docket No. 7163/L). The present invention similarly may be employed with any other type of continuously or otherwise moving conveyor.

[0051] The substrate loading station 201 may include one or more sensors 233 , 235 for detecting movement and/or positions of (1) the conveyor; (2) components of the conveyor 231 (e.g., components used to support substrate carriers being transported by the conveyor 231 as described further below with reference to FIGS. 4 A- 4 E, 6 A- 6 E and 7 C- 7 D); and/or (3) substrate carriers being transported by the conveyor 231 . For example, the sensor 233 may be mounted on the substrate loading station 201 , and the sensor 235 may be mounted on the end effector 225 . Other sensor locations may be employed, as may any suitable sensors (e.g., through beam sensors, reflection-based sensors, etc.).

[0052] FIG. 2B is a side elevational view of a portion of the substrate loading station 201 useful in describing an exemplary embodiment of the sensor 233 . With reference to FIG. 2 B, the sensor 233 comprises a first sensor pair 233 a , 233 a ′ for detecting a speed and/or position of the conveyor 231 ; and/or position of the substrate carrier (and/or the speed with which a substrate carrier 207 is being transported by the conveyor 231 as described further below). The sensor 233 also may include a second sensor pair 233 b , 233 b ′ for detecting whether a substrate carrier 207 is being transported by the conveyor 231 . For example, the first sensor pair 233 a , 233 a ′ may be mounted at an elevation of the conveyor 231 and the second sensor pair 233 b , 233 b ′ may be mounted at an elevation at which substrate carriers are transported by the conveyor 231 as shown in FIG. 2B (e.g., via a mounting bracket B coupled to a frame F of the substrate loading station 201 , or via another suitable mounting mechanism). Each sensor pair may comprise, for example, a Model No. M126E2LDQ light source and a Model No. Q23SN6RMHSQDP receiver available from Banner, Inc. Other sensor arrangements/types may be employed. Exemplary embodiments for the sensor 235 are described further below with reference to FIGS. 2 C-E and FIG. 3 .

[0053] A controller 237 ( FIG. 2A ) may be coupled to the sensors 233 , 235 and to the substrate carrier handler 215 to receive input from the sensors 233 , 235 and to control operation of the substrate carrier handler 215 as described further below. More or fewer than the two sensors 233 , 235 may be provided, and the sensors 233 , 235 may be mounted at locations other than those shown in FIGS. 2A and 2B . The controller 237 may be the same controller used to control operation of a processing tool that the substrate loading station 201 serves, or a separate controller.

[0054] In at least one embodiment of the invention, speed of the conveyor (and/or a substrate carrier being transported by the conveyor) may be directly measured (rather than employing the sensor 233 to indirectly measure conveyor speed). For example, as shown in FIG. 2 A, one or more encoders 240 a , 240 b (described below) may be coupled to the conveyor 231 and directly measure the speed of the conveyor 231 (and any substrate carriers being transported thereby) and provide speed information to the controller 237 . More or fewer than two encoders may be employed. Each encoder may comprise, for example, a U.S. Digital encoder (e.g., an HDS6 quadrature encoder) or any other suitable encoder. A linear encoder, resolver or other positioning device also may be employed to measure conveyor speed and/or position.

[0055] FIG. 3 is a flow chart that illustrates an exemplary process that may be performed by the substrate loading station 201 in accordance with the invention to unload a substrate carrier 207 from the conveyor 231 . FIGS. 4 A- 4 E are schematic side views, illustrating stages of the process of FIG. 3 .

[0056] When an operation for unloading a substrate carrier 207 from the conveyor 231 is to be performed, the horizontal guide 221 of the substrate carrier handler 215 is positioned near the upper ends 217 a , 219 a of the vertical guides 217 , 219 , and the support 223 is positioned near the upstream side 221 a (in the view of FIG. 2 A, the left side although right to left travel may be employed if the conveyor 231 travels right to left) of the horizontal guide 221 .

[0057] The process of FIG. 3 starts at step 301 and proceeds to step 303 . At step 303 the controller 237 receives a signal (e.g., from the sensor 233 or 235 ) to indicate the presence of a substrate carrier 207 that is being transported by the conveyor 231 and that is to be unloaded from the conveyor 231 by the substrate loading station 201 (a “target substrate carrier 207 ”). For example, with reference to FIG. 2 B, the sensor pair 233 b , 233 b ′ may detect the target substrate carrier 207 as a light beam L associated with the sensor pair 233 b , 233 b ′ is blocked by the target substrate carrier 207 . Upon receipt of the sensor signal, the controller 237 controls the substrate carrier handler 215 such that the support 223 (with the end effector 225 attached thereto) is accelerated in the same direction of travel as the conveyor 231 (e.g., to the right in FIG. 2A ) to substantially match the position and speed of the target substrate carrier 207 (step 305 , FIG. 3 ). FIG. 4A illustrates this stage of the process of FIG. 3 .

[0058] In at least one embodiment of the invention, prior to accelerating the end effector 225 so that it substantially matches the position and speed of the target substrate carrier 207 (step 305 ), the controller 237 employs the sensor 233 (or one or more of the encoders 240 a , 240 b ) to determine a speed of the conveyor 231 . Position of the conveyor 231 also may be determined. As stated, the sensor 233 may comprise a first sensor pair 233 a , 233 a ′ ( FIG. 2B ) for detecting a speed of the conveyor 231 (and/or the speed with which a substrate carrier 207 is being transported by the conveyor 231 ), and a second sensor pair 233 b , 233 b ′ for detecting whether a substrate carrier 207 is being transported by the conveyor 231 . Such a speed and/or position determination may be performed prior to or during the unloading of each target substrate carrier 207 , periodically, continuously or at some other interval.

[0059] Based on the speed of the conveyor 231 , the controller 237 may determine a motion profile for the end effector 225 and direct motion of the end effector 225 in accordance with the motion profile to substantially match the speed and position of the end effector 225 and target substrate carrier 207 . The motion profile may be “predetermined”, such that the controller 237 only allows the end effector 225 to begin performing an unload operation (e.g., begin accelerating) if the speed of the conveyor 231 is within a predetermined speed range (e.g., a range that ensures that the end effector 225 will be properly aligned with the target substrate carrier 207 if the end effector 225 is accelerated, moved and/or positioned in accordance with the predetermined motion profile); otherwise, the process of FIG. 3 ends. Such a predetermined motion profile may be employed even if the speed of the conveyor 231 is not measured (e.g., assuming the speed of the conveyor 231 is maintained within a predetermined speed range that ensures that the end effector 225 will be properly aligned with the target substrate carrier 207 if the end effector 225 is accelerated in accordance with the predetermined motion profile).

[0060] The controller 237 may employ the speed of the conveyor 231 to determine a motion profile for the end effector 225 , for example, using a look up table of predetermined motion profiles, using an algorithm to calculate the motion profile, etc. It will be understood that substrate carrier speed, rather than conveyor speed may be measured and employed to determine a motion profile or whether to employ a predetermined motion profile for the end effector 225 . Each motion profile may include all of the accelerations, decelerations, raisings and lowerings (described below) employed by the end effector 225 during an unload operation.

[0061] As stated, in at least one embodiment of the invention, the conveyor 231 may comprise a ribbon-shaped band (e.g., of stainless steel or another suitable material) as described in previously incorporated U.S. patent application serial No. 60/443,087, filed Jan. 27, 2003 (Attorney Docket No. 7163/L). In such an embodiment, the conveyor 231 may be provided with slots or other openings (e.g., slot 231 a in FIG. 2B ) spaced along the conveyor 231 at predetermined spacings, through which a light beam of sensor pair 233 a , 233 a ′ ( FIG. 2B ) may pass as the slots of the conveyor 231 travel by the sensor pair 233 a , 233 a ′. By measuring the time between two successive transmissions of the light beam of sensor pair 233 a , 233 a ′ through the conveyor 231 (via two successive slots in the conveyor) and with knowledge of the distance between the two successive slots, the speed of the conveyor 231 may be determined. The position of the slots 231 a above each substrate carrier 207 ( FIG. 2C ) also provide the controller 237 with conveyor 231 and/or substrate carrier 207 position information.

[0062] In one more embodiment of the invention, the encoders 240 a , 240 b ( FIG. 2A ) may be employed to directly read conveyor speed. For example, each encoder 240 a , 240 b may provide conveyor speed information to the controller 237 and the controller 237 may compare the information received from the encoders 240 a , 240 b as part of an error checking or confidence routine. Such speed monitoring may be performed periodically, continuously or at any other interval. By measuring conveyor speed directly (e.g., via one or more encoders or other positioning devices), and by determining band position via the sensor 233 (e.g., and slots 231 a ) handoffs of substrate carriers between the end effector 225 and the conveyor 231 , while the conveyor 231 is in motion, may be precisely performed as described further below.

[0063] In FIG. 4A the target substrate carrier 207 is shown being transported by the conveyor 231 by means of a carrier engagement member 401 which engages a top flange 402 of the substrate carrier 207 . Other configurations for supporting the substrate carrier 207 may be employed (e.g., one or more mechanisms for supporting the substrate carrier 207 by its sides, bottom or the like). One such configuration for the carrier engagement member 401 is described in previously incorporated U.S. patent application serial No. 60/443,153, filed Jan. 27, 2003 (Attorney Docket No. 8092/L).

[0064] An arrow 403 indicates the direction of motion of the conveyor 231 . The end effector 225 of the substrate carrier handler 215 is illustrated in FIG. 4A in a position below the target substrate carrier 207 and being moved (as indicated by an arrow 405 ) in the same direction as the conveyor 231 at a speed that substantially matches the speed of the target substrate carrier 207 . The end effector 225 thereby substantially matches a velocity (e.g., speed and direction) of the target substrate carrier 207 . In addition, the end effector 225 substantially matches a position of the target substrate carrier 207 . More generally, the end effector 225 substantially matches a motion (velocity and/or position) of the target substrate carrier 207 . As used herein, “substantially matches” means sufficiently matches so that a substrate carrier may be unloaded from and/or loaded onto a moving conveyor and/or carrier engagement member without damaging a substrate contained within the substrate carrier and/or generating potentially damaging particles.

[0065] In the embodiment shown in FIG. 4 A, the target substrate carrier 207 moves with the conveyor 231 . Accordingly, the end effector 225 also substantially matches the speed, velocity, motion and/or position of the conveyor 231 . There may be embodiments in which the conveyor 231 moves at a different rate, or not at all, relative to the target substrate carrier 207 . For example, the carrier engagement member 401 itself may move the target substrate carrier 207 along the conveyor 231 . In this later embodiment, the end effector 225 may not substantially match the speed, velocity and/or position of the conveyor 231 .

[0066] In one or more embodiments of the invention, the end effector 225 may not be positioned at the same location as the trigger (or launch) sensor (e.g., sensor pair 233 b , 233 b ′ of FIG. 2B ) that detects the presence of the target substrate carrier 207 on the conveyor 231 . In such instances, it may be necessary to delay acceleration of the end effector 225 in step 305 to compensate for the differing positions of the end effector 225 and the trigger sensor. This “launch offset” may depend on, for example, the distance between the end effector 225 and the trigger sensor, the speed of the conveyor 231 , etc. A launch offset may be separate from or built into a motion profile for the end effector 225 .

[0067] Referring again to FIG. 3 , at step 307 , the position of the target substrate carrier 207 relative to the end effector 225 is detected (e.g., via a signal or signals from the sensor 235 ( FIG. 2 A)). For example, if the sensor 235 comprises a light source/detector pair, such as a Model No. QS30 sensor system available from Banner, Inc. or the like, the sensor 235 may emit a beam of light toward the target substrate carrier 207 that is only detected by the sensor 235 if the end effector 225 is properly positioned relative to the target substrate carrier 207 (e.g., by providing the substrate carrier 207 with an appropriate reflective surface and/or surface topography such as an angled notch that reflects light toward the sensor 235 only when the end effector 225 is properly positioned relative to the substrate carrier 207 ). FIG. 2C is a perspective view of a portion of the end effector 225 illustrating an exemplary sensor 235 positioned to detect a light beam 241 ( FIG. 2D ) reflected from a notch 243 formed in a portion of a target substrate carrier 207 when the end effector 225 is properly positioned relative to the target substrate carrier 207 . FIG. 2D is an enlarged perspective view of a portion of FIG. 2C . As shown in FIGS. 2 C- 2 D, the sensor 235 may be coupled to the end effector 225 via a suitable bracket or other support structure 247 . Other configurations may be employed.

[0068] In at least one embodiment of the invention, if the end effector 225 is not properly positioned relative to the target substrate carrier 207 , then the process of FIG. 3 ends. Alternatively, in another embodiment of the invention, any necessary adjustments in the position of the end effector 225 relative to the target substrate carrier 207 may be made (step 309 ). For example, the controller 237 may accelerate and/or decelerate the end effector 225 until a proper alignment signal is received from the sensor 235 so as to ensure that kinematic pins 229 ( FIG. 4A ) are properly positioned below alignment features (e.g., concave or otherwise-shaped features 407 ) of the target substrate carrier 207 . It will be appreciated that the steps 307 and 309 are performed while the target substrate carrier 207 and the end effector 225 are in motion, and are performed so that the end effector 225 is positioned below the target substrate carrier 207 while substantially matching speed therewith. Accordingly, the end effector 225 is moved so as to remain adjacent and below the target substrate carrier 207 while the target substrate carrier 207 is in motion. It will be understood that the relative position of the target substrate carrier 207 and the end effector 225 may be detected and adjusted numerous times (or continuously), and that a feedback control loop (not shown) may be employed to ensure that the speed and/or position of the end effector 225 remain substantially matched with that of the target substrate carrier 207 . In yet another embodiment of the invention, steps 307 and 309 may be eliminated (e.g., if a predetermined motion profile is employed that is correlated to the speed of the conveyor 231 and launch time/position of the end effector 225 ). In such an embodiment, the sensor 235 may be eliminated.

[0069] In place of or in addition to the sensor 235 , the encoder 240 a and/or 240 b may be employed to monitor conveyor speed during an unload operation. In response to gross deviations in conveyor speed during an unload operation, the controller 237 may abort the unload operation (e.g., by employing another motion profile that ensures that the end effector 225 does not interfere with the conveyor 231 or substrate carriers being transported thereby). Alternatively, for small conveyor speed variations, the controller 237 may adjust end effector position (e.g., via accelerations or decelerations) to ensure proper unload (or load) operations. A closed loop system comprising the end effector 225 , the sensor 233 , the encoders 240 a and/or 240 b and/or the controller 237 thereby may ensure proper unload (or load) operations despite conveyor speed variations.

[0070] Assuming the end effector 225 is properly positioned relative to the target substrate carrier 207 , following step 307 and/or step 309 in the process of FIG. 3 is step 311 . At step 311 , the controller 237 controls the substrate carrier handler 215 such that the end effector 225 is raised (e.g., the horizontal guide 221 is raised on the vertical guides 217 , 219 to raise the end effector 225 ) while continuing to substantially match the horizontal speed (and/or instantaneous position) of the end effector 225 to the speed (and/or instantaneous position) of the target substrate carrier 207 . The raising of the end effector 225 causes the kinematic pins 229 thereof to come into engagement with concave features 407 on the bottom of the target substrate carrier 207 . Thus the end effector 225 is moved to an elevation at which the conveyor 231 transports substrate carriers 207 . In this manner, the end effector 225 contacts the bottom of the target substrate carrier 207 (as shown in FIG. 4B ). In one or more embodiments of the invention, the end effector 225 preferably contacts the target substrate carrier 207 with substantially zero velocity and/or acceleration as described further below with reference to FIGS. 8 A-D. As the end effector 225 continues to be raised (while the end effector continues to substantially match horizontal speed and/or position with the target substrate carrier 207 ), the target substrate carrier 207 (and in particular its top flange 402 ) is lifted out of engagement with the carrier engagement member 401 of the conveyor 231 , as illustrated in FIG. 4C .

[0071] Next, in step 313 of FIG. 3 , the controller 237 controls the substrate carrier handler 215 to decelerate horizontal motion of the end effector 225 slightly, thereby decelerating the target substrate carrier 207 . The degree of deceleration is such that the target substrate carrier 207 continues to move in the direction indicated by the arrow 403 , but at a slower speed than the conveyor 231 . This allows the carrier engagement member 401 (which had engaged the flange 402 of the target substrate carrier 207 ) to move ahead of the flange 402 , as indicated in FIG. 4D . Once the carrier engagement member 401 has moved out from underneath the flange 402 (as shown in FIG. 4D ), the end effector 225 may be accelerated again, so that the horizontal speed of the end effector 225 and the target substrate carrier 207 supported thereon again substantially matches the horizontal speed of the conveyor 231 to prevent another substrate carrier being transported by the conveyor 231 (e.g., substrate carrier 409 in FIG. 4D ) from colliding with the target substrate carrier 207 .

[0072] In step 315 in FIG. 3 , the end effector 225 is lowered (e.g., by lowering the horizontal guide 221 along the vertical guides 217 , 219 ) to lower the target substrate carrier 207 away from the conveyor 231 . The lowering of the target substrate carrier 207 is illustrated in FIG. 4E . The end effector 225 , having the target substrate carrier 207 supported thereon, may then be decelerated (step 317 , FIG. 3 ) and brought to a halt. As stated, in at least one embodiment of the invention, the above-described end effector 225 accelerations, decelerations, raisings and/or lowerings may be defined by the motion profile determined for the end effector 225 . (Exemplary motion profiles are described below with reference to FIGS. 8 A- 8 D).

[0073] In step 319 , the substrate carrier handler 215 may transport the target substrate carrier 207 supported on the end effector 225 to one of the docking stations 203 ( FIG. 2A ). Alternatively, if the loading station 201 includes one or more storage shelves or other storage locations (e.g., storage shelf 239 , shown in phantom in FIG. 2 A, and adapted to store a substrate carrier), the substrate carrier handler 215 may transport the target substrate carrier 207 to one of the storage locations. (Other and/or more storage locations may be employed). The process of FIG. 3 then ends in step 321 .

[0074] Assuming that the target substrate carrier 207 is brought to one of the docking stations 203 , the target substrate carrier 207 may be handed off by the substrate carrier handler 215 to the docking gripper 211 of the respective docking station 203 . The target substrate carrier 207 then may be docked at the docking station 203 , and opened by the substrate carrier opener 213 of the docking station 203 to allow extraction of a target substrate from the target substrate carrier 207 (e.g., by a substrate handler such as the FI robot 119 of FIG. 1 ). The extracted substrate may be transferred to a processing tool associated with the substrate loading station 201 (e.g., the processing tool 113 of FIG. 1 ) and one or more fabrication processes may be applied to the substrate by the processing tool. Upon completion of the processing in the processing tool, the substrate may be returned to the target substrate carrier 207 at the docking station 203 and the target substrate carrier 207 may be closed and undocked from the docking station 203 . The substrate carrier handler 215 then may transport the target substrate carrier 207 away from the docking station 203 and to a position just below the conveyor 231 (e.g., assuming the substrate carrier 207 is to be returned to the conveyor 231 rather than stored at a storage location such as the storage location 239 ). That is, with the substrate carrier 207 supported on the end effector 225 , the horizontal guide 221 may be moved near the upper ends 217 a , 219 a of the vertical guides 217 , 219 , and the support 223 may be moved to the upstream end 221 a of the horizontal guide 221 . The substrate carrier 207 then may be transferred back onto the conveyor 231 as described below with reference to FIGS. 5 - 6 E.

[0075] An exemplary process that may be performed in accordance with the invention for loading a target substrate carrier 207 onto the conveyor 231 will now be described with reference to FIGS. 5 - 6 E. FIG. 5 is a flow chart that illustrates the inventive substrate carrier loading process. FIGS. 6 A- 6 E are schematic side views showing various stages of the process of FIG. 5 .

[0076] The process of FIG. 5 starts at step 501 and continues with step 503 . At step 503 the controller 237 receives a signal (e.g., from the sensor 233 or 235 ) indicating the presence of a vacant carrier engagement member 401 of the conveyor 231 . In response to this signal, in step 505 , the controller 237 controls the substrate carrier handler 215 so that the end effector 225 (with the target substrate carrier 207 to be transferred to the conveyor 231 thereon) is accelerated along the horizontal guide 221 to substantially match the motion of the vacant carrier engagement member 401 (and/or the conveyor 231 ). For example, the end effector 225 may substantially match the speed and position of the vacant carrier engagement member 401 in the horizontal direction. As stated previously, in one or more embodiments, the end effector 225 may not be positioned at the same location as the trigger sensor (e.g., sensor pair 233 b , 233 b ′ of FIG. 2B ). In such instances it may be necessary to delay acceleration of the end effector 225 in step 505 to compensate for the differing positions of the end effector 225 and the trigger (or launch) sensor.

[0077] In at least one embodiment of the invention, prior to accelerating the end effector 225 so that it substantially matches the position and speed of the vacant carrier engagement member 401 (step 505 ), the controller 237 employs the sensor 233 or one or more encoders 240 a , 240 b coupled to the conveyor 231 to determine a speed of the conveyor 231 . Position of the conveyor 231 also may be determined. Based on the speed of the conveyor 231 , the controller 237 may determine a motion profile for the end effector 225 and direct motion of the end effector 225 in accordance with the motion profile to substantially match the speed and position of the end effector 225 (with the target substrate carrier 207 thereon) to the vacant carrier engagement member 401 onto which the target substrate carrier 207 is to be loaded. The motion profile may be “predetermined”, such that the controller 237 only allows the end effector 225 to begin performing a load operation (e.g., begin accelerating) if the speed of the conveyor 231 is within a predetermined speed range (e.g., a range that ensures that the end effector 225 will be properly aligned with the vacant carrier engagement member 401 if the end effector 225 is accelerated in accordance with the predetermined motion profile); otherwise, the process of FIG. 5 ends.

[0078] Alternatively, the controller 237 may employ the speed of the conveyor 231 to determine a motion profile for the end effector 225 , for example, using a look up table of predetermined motion profiles, using an algorithm to calculate the motion profile, etc. It will be understood that carrier engagement member speed, rather than conveyor speed may be measured and employed to determine a motion profile or whether to employ a predetermined motion profile for the end effector 225 . Each motion profile may include all of the accelerations, decelerations, raisings and lowerings (described below) employed b