DETAILED DESCRIPTION

[0043] In accordance with the invention, substrate carriers are transported by a substrate carrier transport system (e.g., a conveyor), that continues to move during individual substrate or substrate carrier unloading and loading operations. A load/unload mechanism may be associated with a fabrication tool or group of fabrication tools and operates to load and/or unload substrates or substrate carriers from or onto the transport system while the transport system is moving. Each load/unload mechanism includes a load/unload member that is moved during a load or unload operation so as to substantially match the velocity at which the transport system carries the substrate or substrate carrier while the load/unload member disengages or engages a substrate or substrate carrier from, or to, the moving transport system. The load and/or unload member is thus adapted to ensure gentle substrate/substrate carrier handling. Further, the load and/or unload member may be adapted for precise and repeatable substrate/substrate carrier placement.

[0044] FIG. 1 is a top plan view which shows a portion of a substrate carrier transport system provided in accordance with one aspect of the invention. Reference numeral 10 generally indicates the substrate carrier transport system. The substrate carrier transport system 10 may include an overhead transport system or conveyor 12 which conveys substrate carriers 14 . Only a portion of the path of the conveyor 12 is shown in FIG. 1 . It should be understood that the conveyor 12 may advantageously follow an extensive and perhaps serpentine path that extends past every processing location in a fabrication facility.

[0045] The substrate carriers 14 may be any type of substrate carrier, including a sealed pod, an open cassette, or any apparatus with which one or more substrates may be held while the substrate(s) are transported. In one embodiment of the invention, each substrate carrier 14 is a single substrate carrier, i.e. a substrate carrier which holds one and only one substrate at a time. The substrate carriers 14 may generally be constructed like one or another of the substrate carriers disclosed in co-pending and commonly assigned patent application Ser. No. 09/755,394, filed Jan. 5, 2001 (Attorney Docket No. 5092), or commonly assigned patent application Ser. No. 60/407,340 filed Aug. 31, 2002 (Attorney Docket No. 7156/L), for example, both of which are incorporated herein in their entirety by this reference.

[0046] For example, as schematically illustrated in FIGS. 3 ( a ) and ( b ), each substrate carrier 14 may have handles 16 (of which only one is shown in the drawings) mounted on sides 18 (only one shown) of the substrate carriers 14 and including a downwardly-facing V-shaped notch 20 . The V-shaped notch 20 is adapted to be engaged by a bar-shaped end effector 22 which is part of the conveyor system and is connected to the conveyor 12 by a suspension assembly 24 . It will be appreciated that each suspension assembly 24 includes two end effectors 22 , of which only one is shown in the drawings. The two end effectors each respectively engage one of the handles 16 of the substrate carrier 14 . Thus the conveyor 12 is able to transport the substrate carrier 14 with the substrate carrier 14 suspended from the conveyor 12 via the suspension assembly 24 and the handles 16 .

[0047] As will be appreciated from the above-referenced '394 patent application, the substrate carriers 14 may alternatively be equipped with bar-shaped handles that project outwardly from the sides 18 of the substrate carrier 14 , and the conveyor system may have end effectors formed with upward-facing notches to engage the bar-shaped handles of the substrate carriers according to this alternative design, which is not shown in the drawings.

[0048] Although not shown in the drawings, the suspension assemblies 24 of the conveyor 12 may also include a restraint device that extends downwardly to minimize rocking of the substrate carrier 14 while the substrate carrier is suspended from and transported by the conveyor 12 . Such a restraint device is disclosed in the above-referenced '394 patent application. Other substrate carrier designs may be employed. For instance, a substrate carrier having an overhead transfer flange or other mechanism for suspending the substrate carrier may be employed.

[0049] Referring again to FIG. 1 , the conveyor 12 passes by a substrate loading station 26 . The substrate loading station 26 is positioned in front of a fabrication tool 28 , of which only a portion is shown in the drawing. Specifically, the drawing shows only load locks 30 of the fabrication tool 28 . It will be understood that fabrication tool 28 is merely exemplary. Other fabrication tools may not include load locks or may include a greater or lesser number of load locks. As shown in FIG. 1 , the processing tool also includes what is known as a factory interface chamber 31 . Conventionally factory interface chambers contain one or more substrate handlers that extract one or more substrates from a substrate carrier or substrate support and transport the substrates (individually or in a group) into the processing tool (e.g., into a load lock or a processing chamber). It should be noted that not all fabrication tools employ/include a factory interface chamber.

[0050] In a preferred embodiment of the invention, the substrate loading station 26 and fabrication tool 28 represent only one of numerous substrate processing locations in a fabrication facility served by the conveyor 12 .

[0051] Mounted adjacent (near or preferably within the footprint of) the substrate loading station 26 are load/unload mechanisms which are described in more detail below. Each load/unload mechanism may be adapted to load and/or unload a substrate carrier 14 to or from the conveyor 12 while the conveyor 12 is moving.

[0052] The substrate loading station 26 may include one or more load ports or similar locations where individual substrates or substrate carriers are placed for substrate transfer to and/or from a processing tool (e.g., one or more docking stations although transfer locations that do not employ docking/undocking movement may be employed). The load ports may optionally include an automatic door opener for opening a door of a sealed substrate carrier. The substrate loading station 26 may also include one or more storage locations for storing substrate carriers. In one aspect the substrate loading station 26 includes a substrate handler comprising a horizontal and a vertical linear guide to which an end effector for supporting an individual substrate or a substrate carrier, is coupled as shown and described with reference to FIG. 7A . Preferably the substrate loading station 26 includes a plurality of vertically stacked docking stations and/or storage locations.

[0053] The substrate loading station preferably is adapted such that substrate carriers are transferred between the conveyor 12 and the substrate loading station, and among the plurality of vertically stacked docking stations and/or storage locations so as to remain within a tool envelope defined by the footprint of the plurality of vertically stacked docking stations and/or storage locations, and a vertical transfer channel adjacent thereto. In a further aspect, the substrate storage location may include a pair of vertically stacked docking stations and/or storage locations having a transfer channel therebetween, and is adapted such that the substrate carriers are transferred between the conveyor 12 and the substrate loading station, and among the plurality of vertical stacks so as to remain within a tool envelope defined by the pair of vertical stacks, and the transfer channel therebetween.

[0054] As will be understood, the mechanism for loading/unloading a substrate or substrate carrier from the conveyor may vary considerably and still achieve the function of substantially matching the velocity of the conveyor 12 at the point where the substrate carrier is contacted. Although it is preferred that a load/unload mechanism operates within the footprint of the docking station(s) and/or storage location(s)(or within the tool envelope), any mechanism that substantially matches velocity with a moving conveyor so as to load/unload substrate carriers therefrom will fall within the scope of the present invention. The load/unload mechanisms described herein are merely exemplary. For instance, in one aspect, a load/unload mechanism may be a rotary mechanism (e.g., a rotating platform or arm that travels along a rotary path as described further with reference to FIGS. 1 - 6 or as described in commonly assigned, copending application serial no.______ filed herewith (AMAT No. 7024) titled “Method And Apparatus For Unloading Substrate Carriers From Substrate Carrier Transport System”, which is hereby incorporated by reference herein in its entirety. In a further aspect the load/unload mechanism may comprise a substrate handler of the substrate loading apparatus 26 , as described further with reference to FIGS. 7 A- 13 D.

[0055] FIG. 2 is a schematic side view of the conveyor 12 at the location where it passes an exemplary substrate loading station 26 having a rotary load/unload mechanism. The front 34 of the substrate loading station 26 is schematically shown in FIG. 2 . As seen in FIGS. 2 and 3 ( a ), in this aspect each load/unload mechanism 32 includes a load/unload member 36 mounted on a four bar mechanism 37 of which two bars 38 are shown in the drawings. (To simplify the drawing, the conveyor 12 is represented schematically by an arrow 12 in FIG. 2 , and the suspension assemblies 24 ( FIG. 3 ( a ) are omitted.) The four bar mechanism 37 allows the load/unload member 36 to be moved in a circular path indicated at 40 in FIG. 3 ( a ). It will be appreciated that the circular path 40 is defined in a vertical plane.

[0056] Also shown in FIG. 2 are a plurality of substrate or substrate carrier storage shelves and a plurality of docking stations. Although not shown in FIG. 2 , the loading station 26 may also comprise a substrate or substrate carrier handler. In a preferred aspect, the substrate/substrate carrier handler may be similar to that shown in FIG. 7 A, wherein the substrate/substrate carrier handler comprises vertical and horizontal linear guides and an end effector adapted to move linearly therealong via the vertical and horizontal guides.

[0057] FIG. 3 ( a ) is a schematic side view of the conveyor 12 , showing a substrate carrier 14 engaged by a suspension assembly 24 of the conveyor 12 approaching the load/unload mechanism 32 . FIG. 3 ( a ) shows the load/unload mechanism in its home position. The load/unload mechanism 32 operates so that the load/unload member 36 is moved upwardly and then, continuing through the circular path 40 , is moved so that it has a horizontal speed component that substantially matches the horizontal speed of the substrate carrier 14 (and the conveyor 12 ) at a point where the load/unload member 36 contacts the substrate carrier 14 (in this example the bottom surface 42 of the substrate carrier 14 ) to lift the substrate carrier 14 out of engagement with the suspension assembly 24 of the conveyor 12 . Thus the movement of the substrate carrier 14 relative to the load/unload member 36 , at the time of engagement of the substrate carrier 14 by the load/unload member 36 , is substantially entirely in a vertical direction. Loading of the substrate carrier 14 on the conveyor 12 is thereby accomplished substantially without jarring the substrate carrier 14 .

[0058] The load/unload mechanism 32 may include a motor, which is not shown, to drive the four bar mechanism 37 . The motor may be controlled by a controller C programmed to cause the four bar mechanism 37 , and consequently the load/unload member 36 to be driven at a rotational rate that varies over the course of movement of the load/unload member 36 through the circular path 40 . In one alternative, a cam arrangement (not shown) may drive the four bar mechanism 37 and the load/unload member 36 at a variable rotational rate. It is alternatively contemplated that the load/unload mechanism may be driven by a drive mechanism coupled to, and driven from, the conveyor 12 .

[0059] The load/unload member 36 may be in the form of a plate that may include a shock absorbing material. However, to save weight in the construction of the load/unload member, it may be in the form of a lifting frame and/or may have pins on air solenoids for contacting the bottom surface 42 of the substrate carrier 14 .

[0060] FIG. 3 ( b ) is a view similar to FIG. 3 ( a ) showing the load/unload mechanism 32 again in its home position and holding the substrate carrier 14 which was formerly engaged by the suspension assembly 24 of the conveyor 12 and has been lifted off the suspension assembly 24 by the load/unload mechanism 32 . FIG. 3 ( b ) also shows the suspension assembly 24 continuing to move and moving away from the load/unload mechanism 32 .

[0061] FIGS. 4 ( a )-( f ) are a sequence of drawings which illustrate in more detail an operation in which the load/unload mechanism 32 unloads a substrate carrier 14 from the conveyor 12 . (To simplify the drawings, the conveyor 12 is not shown in FIGS. 4 ( a )-( f ).)

[0062] FIG. 4 ( a ) shows the load/unload mechanism 32 in its home position at which it may await approach of a substrate carrier 14 that is to be unloaded from the conveyor 12 by the load/unload mechanism 32 . As the substrate carrier 14 approaches, the load/unload mechanism 32 , in the example shown, is moved from the home position of FIG. 4 ( a ) to the position shown in FIG. 4 ( b ), which is midway between the home position and the apex of the circular path 40 of the load/unload mechanism 32 .

[0063] FIG. 4 ( c ) shows the load/unload mechanism 32 at a point in its cycle at which it contacts the substrate carrier 14 from below to lift and disengage the substrate carrier 14 from the conveyor 12 . At the point in time represented by FIG. 4 ( c ), the load/unload member 36 is moved at a rotational rate that results in a horizontal displacement of the load/unload member 36 at a velocity that substantially matches the velocity of the substrate carrier 14 (i.e., substantially matches the velocity of the conveyor 12 ). Consequently, there may be substantially no relative horizontal movement between the load/unload member 36 and the substrate carrier 14 at the point in time represented by FIG. 4 ( c ). Thus the load/unload member 36 may lift the substrate carrier 14 out of engagement with the conveyor 12 without jarring the substrate carrier 14 . In one embodiment of the invention, the load/unload member 36 imparts an upward acceleration to the substrate carrier 14 of about 1G or less so as to avoid generating particles and/or damaging the substrate (not separately shown) that is contained within the substrate carrier 14 .

[0064] At the next stage of the unload operation, represented by FIG. 4 ( d ), the load/unload mechanism 32 is at the apex of its cycle, having lifted the substrate carrier 14 out of engagement with the conveyor 12 . In one embodiment of the invention, the vertical distance between the positions shown in FIGS. 4 ( c ) and ( d ) may be on the order of one-half inch. The substrate carrier 14 may be supported on the load/unload member 36 by the bottom surface 42 of the substrate carrier 14 , for example, and is now decelerated in a horizontal direction, to allow the end effectors 22 ( FIG. 3 ( a )) of the suspension assembly 24 ( FIG. 3 ( a )) of the conveyor 12 to move ahead of the substrate carrier 14 .

[0065] FIG. 4 ( e ) represents the next stage of the unload cycle, at which the load/unload mechanism 32 , with the substrate carrier 14 supported thereon, is at a mid point between its apex and its home position. Then, FIG. 4 ( f ) shows the load/unload mechanism back at its home position, and supporting the unloaded substrate carrier 14 .

[0066] FIGS. 5 ( a )-( f ) are a sequence of views like FIGS. 4 ( a )-( f ), but illustrating an operation for loading a substrate carrier 14 on the conveyor 12 . As in FIGS. 4 ( a )( f ), the conveyor 12 is not shown in FIGS. 5 ( a )-( f ) to simplify the drawings.

[0067] FIG. 5 ( a ) shows the load/unload mechanism 32 in its home position, supporting a substrate carrier 14 that is to be loaded onto the conveyor 12 . As an empty suspension assembly 24 of the conveyor 12 approaches, the load/unload mechanism 32 is moved to the position shown in FIG. 5 ( b ), i.e., midway between the home position and the apex, and continues to be moved up to its apex, as indicated at FIG. 5 ( c ). The load/unload mechanism 32 continues to be moved along its circular path 40 ( FIG. 3 ( a )) to and through the point in its cycle illustrated in FIG. 5 ( d ). FIG. 5 ( d ) illustrates the position at which the load/unload mechanism 32 lowers the substrate carrier 14 into engagement with the end effectors 22 of the conveyor 12 . At the position illustrated in FIG. 5 ( d ) the load/unload mechanism 32 is being rotated at a rotational velocity that results in a horizontal speed component that matches the velocity (e.g., horizontal speed) of the conveyor 12 . Thus the movement of the substrate carrier 14 relative to the end effectors 22 of the conveyor 12 at the time of engagement of the substrate carrier 14 by the end effectors 22 is substantially entirely in a vertical direction, thereby accomplishing loading of the substrate carrier 14 on the conveyor 12 substantially without jarring the substrate carrier 14 .

[0068] FIG. 5 ( e ) shows the load/unload mechanism 32 at a midpoint between its apex and its home position, and no longer supporting the substrate carrier 14 , which has been loaded onto to the conveyor 12 . FIG. 5 ( f ) shows the load/unload mechanism 32 back at its home position, without the substrate carrier 14 .

[0069] As in the apparatus disclosed in the above-referenced '394 patent application, sensors (not shown) may be employed to track the positions of substrate carriers 14 . As will be understood from the disclosure of the '394 patent application, one such sensor may be a through beam sensor including a light beam transmitter and a light beam receiver disposed on opposite sides of a path through which the conveyor 12 transports the substrate carriers 14 . The through beam sensors may be used to track passage of leading and trailing edges of the substrate carriers 14 . If it is desired to track a center of the substrate carriers 14 , a reflector (not shown) may be placed on a surface (e.g., the bottom surface 42 ) of the substrate carriers 14 and sensors having both transmitter and receiver on the same side of the substrate carrier transport path may be provided. The signals from the sensor receivers may be provided to a controller (not shown) for the substrate carrier transport system 10 .

[0070] It will be appreciated that the substrate carrier 14 may be transported with its front side facing the direction in which it is being transported. “Front side” meaning the side of the substrate carrier 14 which has an opening (not shown) through which a substrate or substrates may be extracted from the substrate carrier 14 . If the substrate carrier 14 is transported by the conveyor 12 with the front side of the substrate carrier 14 facing the direction in which it is transported, then it may be necessary to rotate the substrate carrier 14 (90° counter clockwise in the view shown in FIG. 1 ) so that the front side of the substrate carrier 14 is presented toward a load lock 30 of the fabrication tool 28 . For the purpose of so rotating the substrate carrier 14 , the load/unload mechanism 32 may be mounted on a rotatable platform (not shown) of the type discussed in the above-referenced '394 patent application.

[0071] As an alternative to rotating the substrate carrier 14 in this manner, an embodiment of the invention as shown in FIG. 6 may be provided. FIG. 6 is a top plan view similar to FIG. 1 , but showing a substrate loading station 26 ′ installed so that it extends perpendicular to the path of travel of the conveyor 12 . If load/unload mechanism like those of FIG. 2 are employed, the four bars will be rotated 90° from the orientation shown in FIG. 2 , so as to be able to rotate in the direction the conveyor 12 travels.

[0072] It will be noted that in the embodiment of FIG. 6 the fabrication tool 28 is installed with its load locks 30 facing the direction from which substrate carriers 14 are transported by the conveyor 12 . Consequently, assuming that the substrate carriers 14 are transported with their front sides facing in the direction of transport, there is no need in the embodiment of FIG. 6 to rotate the substrate carriers 14 to permit extraction of a substrate or substrates therefrom at or in front of the load locks 30 .

[0073] Although only one fabrication tool 28 is shown in FIG. 6 , it is further contemplated, pursuant to the teachings of co-pending and commonly assigned U.S. patent application Ser. No. 09/517,227, filed Mar. 2, 2000 (Attorney Docket No. 3945), to have the substrate loading station 26 ′ extend farther from the conveyor 12 to accommodate one or more additional fabrication tools 28 installed parallel to the fabrication tool 28 shown in FIG. 6 and farther away from the conveyor 12 . The '227 patent application is incorporated herein in its entirety by this reference.

[0074] In operation, the conveyor 12 may continuously transports substrate carriers 14 from location to location within the fabrication facility. A substrate carrier 14 is unloaded by a load/unload mechanism 32 at a substrate loading station 26 or 26 ′ from the conveyor 12 while the conveyor and the substrate carrier are moving. The substrate carrier 14 is rotated or otherwise reoriented, if necessary, so that its opening faces the fabrication tool 28 , and a substrate carrier handler (e.g., as shown in FIG. 7A ) associated with the substrate loading apparatus removes the substrate carrier 14 from the load/unload mechanism 32 . The substrate carrier handling robot either places the substrate carrier 14 at a docking station (as further described with reference to FIG. 7A ) for the fabrication tool 28 , or places the substrate carrier 14 on a storage shelf of the substrate loading station 26 to await subsequent transfer by the substrate carrier handler (e.g., as shown in FIG. 7A ) to a docking station of the fabrication tool. In one aspect, the substrate loading station 26 may comprise an apparatus having one or more vertically stacked storage shelves such as an Applied Materials' Bay Distributed Stocker, as disclosed in U.S. Pat. No. 6,283,692. Alternative substrate loading stations are described with reference to FIGS. 7 A- 13 D.

[0075] Once at the load port, the substrate carrier may be opened and interfaced to the fabrication tool 28 in a conventional manner. In an aspect which does not employ the factory interface chamber 31 of FIG. 1, a substrate or substrates may be extracted from the substrate carrier and brought into the fabrication tool 28 via a load lock 30 which after receiving one or more substrates at atmospheric pressure closes and pumps to a vacuum pressure. The substrate or substrates are then extracted and transferred to one or more processing chambers (not shown) of the fabrication tool for processing as is known in the art. After processing, the substrate or substrates are returned to the load lock which then vents to atmospheric pressure. Thereafter the substrate or substrates are loaded back into the substrate carrier 14 and the substrate carrier is closed. The substrate carrier handling robot transfers the substrate carrier to a load/unload mechanism 32 , possibly after the substrate carrier has been stored on a storage shelf of the substrate loading station 26 .

[0076] As previously described, the load/unload mechanism loads the substrate carrier onto an empty suspension assembly 24 of the conveyor 12 while the conveyor is moving. The conveyor 12 transports the substrate carrier away from the substrate loading apparatus and to another processing location, at which the substrate carrier is again unloaded without stopping the conveyor.

[0077] An alternative embodiment of the substrate loading station which employs a substrate handler of the substrate loading station as a load/unload mechanism will now be described with reference to FIGS. 7 A- 13 E. Note that the rotary load/unload mechanism of FIGS. 2 - 6 may be employed within the substrate loading station of FIG. 7 A, in addition to use of the substrate handler for load and/or unload operations, or alternatively thereto. Load/unload mechanisms 32 are therefore shown in phantom in FIG. 7A .

[0078] FIG. 7A is a front elevational view of a substrate loading station 201 provided in accordance with the invention. Although not shown in FIG. 7 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 .

[0079] 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. 7 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 31 a 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 Ser. 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.

[0080] Each docking station 203 may include a port 209 through which a substrate may be transferred to the factory interface (e.g., factory interface 31 a 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 Ser. 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 Ser. 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.

[0081] 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 .

[0082] 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.

[0083] 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. 7 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. 7A ) 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 Ser. 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.

[0084] 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 Ser. 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.

[0085] 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. 9 A-E, 11 A- 6 E and 12 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.).

[0086] FIG. 7B 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. 7 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. 7 C-E and FIG. 8 .

[0087] A controller 237 ( FIG. 7A ) 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. 7A and 7B . 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.

[0088] 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. 7 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.

[0089] FIG. 8 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. 9 A- 9 E are schematic side views, illustrating stages of the process of FIG. 8 .

[0090] 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. 7 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 .

[0091] The process of FIG. 8 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. 7A ) to substantially match the position and speed of the target substrate carrier 207 (step 305 , FIG. 8 ). FIG. 9A illustrates this stage of the process of FIG. 8 .

[0092] 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. 7B ) 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.

[0093] 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. 8 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).

[0094] 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.

[0095] 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 Ser. 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. 7B ) spaced along the conveyor 231 at predetermined spacings, through which a light beam of sensor pair 233 a , 233 a ′ ( FIG. 7B ) 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. 7C ) also provide the controller 237 with conveyor 231 and/or substrate carrier 207 position information.

[0096] In one more embodiment of the invention, the encoders 240 a , 240 b ( FIG. 7A ) 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.

[0097] In FIG. 9A 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 Ser. No. 60/443,153, filed Jan. 27, 2003 (Attorney Docket No. 8092/L).

[0098] 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. 9A 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.

[0099] In the embodiment shown in FIG. 9 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 .

[0100] 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 .

[0101] 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. 7 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. 7C 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. 7D ) 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. 7D is an enlarged perspective view of a portion of FIG. 7C . As shown in FIGS. 7 C-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.

[0102] 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. 8 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. 9A ) 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.

[0103] 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.

[0104] 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. 5B ). 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. 13 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. 9C .

[0105] Next, in step 313 of FIG. 8 , 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. 9D . Once the carrier engagement member 401 has moved out from underneath the flange 402 (as shown in FIG. 9D ), 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. 9D ) from colliding with the target substrate carrier 207 .

[0106] 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. 9E . The end effector 225 , having the target substrate carrier 207 supported thereon, may then be decelerated (step 317 , FIG. 8 ) 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. 13 A-D).

[0107] 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. 7A ). 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. 7 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. 8 then ends in step