Abstract:
The invention provides a substrate processing apparatus including a processing tank for processing substrates, a transporting path provided along the processing tank, a substrate transporting device moving along the transporting path for transporting the substrates, wherein the substrate processing apparatus and the substrate transporting device mounted thereto may realize the improvement of the throughput of substrate processing without increasing the area for installing the substrate processing apparatus. There are provided at least two substrate transporting devices that are capable of moving on the identical transporting path. The movable ranges of the respective substrate transporting devices for transporting the substrates are overlapped with respect to each other. When transportation of the substrates is required simultaneously at a plurality of processing tanks in scheduling data prepared by a scheduler, the scheduling data is determined by referencing substrate transportation sharing conditions.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a substrate processing apparatus for performing processing, such as washing, on substrates, such as silicon wafers, and to a substrate transporting device mounted to the substrate processing apparatus for transporting the substrates, such as silicon wafers, to a processing tank.  
           [0003]    2. Description of the Related Art  
           [0004]    In a substrate processing apparatus provided with a plurality of processing tanks and drying tanks containing various types of processing solutions (drug solution, rinsing solution) respectively, a substrate, such as a silicon wafer, is soaked into the processing solution in the processing tank by a substrate transporting device according to the processing flow. Provided on the upstream side of the substrate processing apparatus are a stocker for accommodating unprocessed substrates and transporting the same to the delivery position for delivering the same to the substrate transporting device mounted to the substrate processing apparatus and a substrate loading/unloading unit.  
           [0005]    The stocker is a device for delivering the unprocessed substrates to the substrate processing apparatus, and transporting the processed substrates, which have passed through the substrate processing apparatus, to a subsequent process. Generally, the unprocessed substrates are delivered from the previous process in lots each including a plurality of substrates disposed in alignment in a cassette. Transporting means includes a cassette transporting system in which the substrates are transported together with the cassette, and so-called a cassette-less system in which only the substrates in the cassettes are held and transported. When constructing the apparatus, either one of these systems is selected as needed.  
           [0006]    The substrate loading/unloading unit includes an unprocessed substrate loading unit for holding and taking all the substrates out from the cassette on the stocker delivered in the cassette transporting system and transporting them to the delivery position for delivering the substrates to the substrate transporting device of the substrate processing apparatus and a processed substrate unloading unit for receiving the processed substrates at the delivery position of the substrate transporting device, storing them into the cassette, and delivering them to the stocker.  
           [0007]    [0007]FIG. 1 is a schematic drawing showing a construction of principal portion of a substrate processing apparatus  50  in the related art. As shown in FIG. 1, the substrate processing apparatus  50  includes a plurality of processing tanks  10 - 15  containing various types of processing solutions respectively, fastener washing tanks  8  and  9 , a drying tank  20 , an unprocessed substrate loading unit  35 , a processed substrate unloading unit  36 , substrate transporting devices R 1 , R 2 , and R 3  moving along a transporting track  4 . FIG. 1 also shows movable ranges of the substrate transporting devices R 1 , R 2 , and R 3 . The substrate transporting devices R 1 , R 2 , and R 3  are constructed to move on the single track  4 . The substrate transporting device R 1  holds substrates delivered by the unprocessed substrate loading unit  35  and transports it while soaking it into the processing tanks  10 ,  11 ,  12 , and  13  in sequence. The delivered substrates are subjected to processing, such as washing, in the processing tanks  10 - 13 . The substrate transporting device R 2  transports the substrates having processed in the processing tank  13  and soaks them into the processing tanks  14  and  15  located downstream thereof in sequence. The substrates having processed, for example, washed, in the processing tanks  14  and  15 , are transported to the drying tank  20 . The substrates having dried in the drying tank  20  are delivered to the processed substrate unloading unit  36  by the substrate transporting device R 3 . Delivery of the substrates between the substrate transporting devices R 1  and R 2  is carried out at the processing tank  13 , and delivery of the substrates between the substrate transporting devices R 2  and R 3  is carried out at the drying tank  20 . The processing tank at which delivery of the substrates between the substrate transporting devices is performed is referred to as transfer tank. The substrate transporting devices for transporting the substrates to the processing tanks other than the transfer tank are fixed. The substrate transporting devices R 1 , R 2 , and R 3 , shown in FIG. 1, are of cassette-less system.  
           [0008]    Preparation of scheduling data for controlling the substrate transporting devices R 1 , R 2 , and R 3  will now be described. The substrate transporting devices R 1 , R 2 , and R 3  are controlled according to scheduling data prepared based on the recipe (control program), which includes control parameters such as processing time assigned for each processing tank. FIG. 2 is a flowchart for preparing a control sequence for the substrate processing apparatus by a scheduler in the related art. As shown in FIG. 2, data on the number of processing tanks to be installed, the processing time assigned for each processing tank, the type of processing solution, the movable range of the substrate transporting device, the transporting time, the processing conditions relating operating time of a lifter, and the transporting conditions, is entered through an input device such as a keyboard or by measurement of the transporting time or the operating time of the lifter (teaching) (Step S 20 ). The computer then prepares a processing schedule based on entered data (Step S 21 ). According to the prepared schedule, the computer calculates the time to start loading/unloading the substrates into/out of each processing tank based on data on the processing time and the type of processing solution in each processing tank. The computer also determines whether or not washing of the fastener of the substrate transporting device is necessary depending on the type of processing solution contained in the processing tank. Accordingly, the time to start and time to terminate processing for every processing tank, and the timing of loading and unloading of the substrates for each processing tank of the substrate transporting device are determined.  
           [0009]    Then, whether or not the operation of the substrate transporting devices is required simultaneously at a plurality of processing tanks is determined from the timing of loading and unloading into/out of the substrate transporting device (Steps S 22  and S 23 ).  
           [0010]    When the operation of the substrate transporting device is not required simultaneously at a plurality of processing tanks, the procedure goes to Step S 25 . When the operation of the substrate transporting device is required simultaneously at a plurality of processing tanks, the procedure goes to Step S 24 , in which the schedule is changed so that the timing of loading the substrates is delayed (Step S 24 ), and then goes to Step S 22 . Then, when it is determined that the substrate transporting device can manage processing, the changed schedule is fixed (Step S 25 ). Fixed schedule data is transferred to a control unit of the substrate processing apparatus  1  (Step S 26 ), and then the substrate processing apparatus  1  starts processing (Step S 27 ). With the steps described above, the substrates in the unprocessed substrate loading unit  35  are transported to a first processing tank by a substrate transporting device RT 1 , and processing of those substrates is started. (See Japanese Examined Patent Application Publication No. 7-22144, Japanese Unexamined Patent Application Publication No. 10-172939, Japanese Unexamined Patent Application Publication No. 2002-172367)  
           [0011]    As described above, since the processing time is predetermined by scheduling data for each processing tank, it is necessary to take the substrates out from the processing tank immediately after the processing time assigned for each processing tank has elapsed and to transport it to the next processing tank. However, according to the substrate transporting device in the related art, the movable range of the substrate transporting device across the plurality of tanks is fixed. Therefore, when the substrate transporting device is transporting one lot of substrates in the movable range, and if transportation of another lot of substrates in another processing tank is required in the movable range, the substrate transporting device in operation cannot access to another processing tank. Therefore, another lot of substrates in another processing tank has to wait until the current operation of the substrate transporting device is terminated.  
           [0012]    [0012]FIG. 3 is a timing chart showing processing of substrates in each processing tank in chronological order. Arrows shown in FIG. 3 represent the substrate transporting operations to be performed by the substrate transporting device, and hutched bars represent that processing is in progress in the processing tank, and the length of the hutched bar represents the processing time.  
           [0013]    As shown in FIG. 3, when groups of substrates (a first lot, a second lot, and a third lot shown by circles) shown in FIG. 3 are loaded in sequence starting from the first processing tank  10  from the unprocessed substrate loading unit  35 , since the processing time is limited for each processing tank, two processing tanks require transportation of the substrates simultaneously at the timings t1 and t2, as shown in FIG. 3, namely, when transferred from the processing tank  10  to the processing tank  11 , and from the processing tank  12  to the processing tank  13 . Since only one substrate transporting device is available in the range from the processing tank  10  to the processing tank  13 , one processing tank has to wait until transportation at another processing tank is terminated.  
           [0014]    In order to solve such a problem, it is necessary to delay loading of the substrates into the first processing tank so that completion of processing of the substrates does not occur at a plurality of tanks simultaneously. In the conventional system, as shown in FIG. 4, loading of the groups of substrates (first lot, second lot) into the first processing tank is delayed, so that completion of processing of the substrates does not occur at a plurality of tanks simultaneously.  
           [0015]    However, by delaying loading of the substrates into the processing tank, a throughput of the substrate in the substrate processing apparatus  50  is restrained, and thus the number of substrates that can be processed during a predetermined time period is reduced. Therefore, improvement of the throughput of substrate processing in the substrate processing apparatus  50  is a subject to be achieved.  
         SUMMARY OF THE INVENTION  
         [0016]    Accordingly, it is an object of the invention to provide a substrate processing apparatus and a substrate transporting device mounted thereto, in which improvement of the throughput of substrate processing is achieved by overlapping movable ranges of a plurality of substrate transporting devices for transporting substrates across a plurality of tanks with respect to each other and enabling the plurality of substrate transporting devices to be operated simultaneously within the respective movable ranges without increasing the area for installation.  
           [0017]    According to the invention, there is provided a substrate processing apparatus including processing tanks for processing substrates, a transporting track provided along the processing tanks, and substrate transporting devices moving along the transporting track for receiving, delivering and transporting the substrates, wherein at least two such substrate transporting devices are provided on the identical transporting track, and the substrate transporting devices are operable in common operating ranges across a plurality of processing tanks.  
           [0018]    According to the invention, there is provided a substrate processing apparatus including processing tanks for processing substrates, a transporting track provided along the processing tanks, and substrate transporting devices moving along the transporting track for receiving, delivering and transporting the substrates, wherein a shuttle for transporting unprocessed substrates is provided at a level higher than the substrate transporting devices in parallel with the transporting track.  
           [0019]    According to the invention, there is provided a substrate processing apparatus including processing tanks for processing substrates, a transporting track provided along the processing tanks, and substrate transporting devices moving along the transporting track for receiving, delivering and transporting the substrates, wherein at least two such substrate transporting devices are provided on the identical transporting track, the substrate transporting devices are operable in common operating ranges across a plurality of processing tanks, and a shuttle for transporting unprocessed substrates are provided at the level higher than the substrate transporting devices in parallel with the transporting track.  
           [0020]    The substrate processing apparatus according to the invention further includes a specific tank as fastener washing means for washing substrate fasteners of the substrate transporting device for each of the substrate transporting devices.  
           [0021]    The substrate processing apparatus according to the invention further includes a substrate lowering unit for receiving the unprocessed substrates from the shuttle and sending the unprocessed substrates down to the delivery position of the substrate transporting device.  
           [0022]    The substrate processing apparatus according to the invention further includes a substrate hoisting unit for hoisting and transporting the unprocessed substrate to the shuttle.  
           [0023]    The substrate processing apparatus according to the invention preferably includes a unit for loading of unprocessed substrate for transporting the unprocessed substrates from a position for loading the unprocessed substrates to the substrate hoisting unit.  
           [0024]    The substrate processing apparatus according to the invention preferably includes a unit for unloading of a processed substrate for receiving the processed substrates from the substrate transporting device and transporting them to the position for unloading the substrates.  
           [0025]    According to the invention, there is provided a substrate transporting device in the substrate processing apparatus for controlling the substrate transporting device based on scheduling data prepared by the scheduler based on processing conditions and transporting conditions, which are entered in advance, wherein in the case in which transportation of the substrates occurs at the plurality of processing tanks simultaneously according to the scheduling data prepared by the scheduler, scheduling data is determined by referencing substrate transportation sharing conditions.  
           [0026]    The scheduler of the substrate transporting device in the substrate processing apparatus according to the invention preferably selects a substrate transporting device which performs transporting operation for loading and unloading the substrates into/from the predetermined processing tank among the plurality of substrate transporting devices in the common operating region.  
           [0027]    As described thus far, the substrate processing apparatus and the substrate transporting device mounted thereto according to the invention is capable of transporting the substrates in the plurality of processing tanks simultaneously by providing a plurality of the substrate transporting devices on the identical transporting track and controlling them to be able to move along the plurality of tanks in the respective movable range which are overlapped with respect to each other. Accordingly, improvement of the throughput of substrate processing in the substrate transporting device  50  is achieved.  
           [0028]    In addition, according to the substrate processing apparatus of the invention, since the shuttle for supplying specifically the unprocessed substrate is provided without increasing the area for installation, the substrates can be supplied to a buffer independent from the operation of the substrate transporting device, and thus improvement of throughput of the substrate processing is achieved. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0029]    [0029]FIG. 1 is a schematic drawing showing a construction of principal portion of a substrate processing apparatus in the related art;  
         [0030]    [0030]FIG. 2 is a flowchart for preparing a control sequence for the substrate processing apparatus by a scheduler in the related art;  
         [0031]    [0031]FIG. 3 is a timing chart showing processing of substrates in each processing tank in chronological order;  
         [0032]    [0032]FIG. 4 is a timing chart showing a case in which loading of the substrates into a first processing tank is delayed to avoid simultaneous occurrence of completion of processing at a plurality of tanks;  
         [0033]    [0033]FIG. 5 is a drawing showing a construction of a substrate processing apparatus according to the invention;  
         [0034]    [0034]FIG. 6 is a drawing showing a construction and an operation of a substrate transporting device in the substrate processing apparatus according to the invention;  
         [0035]    [0035]FIGS. 7A to FIG. 7E are drawings showing delivery of the substrates into a processing tank of the substrate transporting device;  
         [0036]    [0036]FIG. 8 is a drawing showing the movable region of the substrate transporting devices in the substrate processing apparatus on a transporting track;  
         [0037]    [0037]FIG. 9 is a drawing showing a transporting path of the substrate including a stocker, a substrate loading/unloading unit, and the substrate processing device viewed from the front;  
         [0038]    [0038]FIG. 10 is a flowchart for preparing a control sequence of the substrate processing apparatus by a scheduler;  
         [0039]    [0039]FIG. 11 is a timing chart showing processing of the substrate in each processing tank according to the control sequence for the substrate processing apparatus prepared by the scheduler. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0040]    Referring now to the drawings, an embodiment of a substrate processing apparatus and a substrate transporting device mounted thereto according to the invention will be described. FIG. 5 is a drawing showing a construction of the substrate processing apparatus according to the invention; FIG. 6 is a drawing showing a construction and operation of the substrate transporting device mounted thereto according to the invention; FIG. 7 shows delivery of the substrates into a processing tank of the substrate transporting device; FIG. 8 is a drawing showing the movable region of the substrate transporting devices in the substrate processing apparatus on a transporting track; and FIG. 9 is a drawing showing a transporting path of the substrate including a stocker, a substrate loading/unloading unit, and the substrate processing device viewed from the front. The portions having the same construction and function as the substrate processing apparatus in the related art shown in FIG. 1 are designated by the same reference numbers in the description.  
         [0041]    As shown in FIG. 5, a substrate processing apparatus  1  according to the invention includes processing tanks  10 - 15 , fastener washing tanks  8  and  9 , a drying tank  20 , a buffer  6 , an unprocessed substrate loading unit  35 , a processed substrate unloading unit  36 , substrate transporting devices RT 1 , RT 2 , and RT 3  moving on a transporting track  4 , a substrate hoisting unit  23 , a substrate lowering unit  24 , and a shuttle  3 . The substrate processing apparatus  1  is used in combination with the unprocessed substrate loading unit  35  and the substrate hoisting unit  23 , which receive the unprocessed substrates supplied by a stocker  30  (shown in FIG. 9) and transport them to the position for delivering them to the shuttle  3 .  
         [0042]    The stocker  30  is a device for loading the unprocessed substrates, such as silicone wafers, to the substrate processing apparatus  1  and transporting the processed substrates, which has passed through the substrate processing apparatus  1 , to the subsequent processes.  
         [0043]    The unprocessed substrate loading unit  35  which serves as substrate loading unit takes all the substrates from the cassette in the stocker  30  by fastening altogether and transfers them to the delivery position of the substrate hoisting unit  23 .  
         [0044]    The processed substrate unloading unit  36  which serves as substrate unloading unit receives the processed substrates transported by the substrate transporting device RT 3 , stores them in a cassette, and delivers to the stocker  30 .  
         [0045]    As shown in FIG. 5, the buffer  6  is a device for temporarily accommodating the plurality of substrates transported from the shuttle  3 , and moving the substrates to the position for delivering them to the substrate transporting device RT 1 .  
         [0046]    As shown in FIG. 5, the processing tanks  10 - 15  are devices to be used for processing, such as washing, and containing processing solutions respectively, in which the substrates are soaked. The processing tanks  10 - 15  are disposed in line along the transporting track  4  in the order of processing of the substrates. The substrates transported by the substrate transporting devices RT 1  and RT 2  are loaded into the processing tanks and unloaded from the processing tanks of the substrate after having processed by lifters provided in the processing tanks respectively.  
         [0047]    Tables  10   a - 15   a  (shown in FIG. 5) of the lifters in the processing tanks  10 - 15  are devices for receiving the substrates from the substrate transporting device at the delivery position, soaking them into the processing tanks  10 - 15 , and lifting the processed substrates to the delivery position for delivering them to the substrate transporting devices.  
         [0048]    The lifter is provided with an elevating unit which is movable in the vertical direction. The elevating unit has a substrate holding potion for holding the substrates, so that the substrates received by the substrate transporting devices RT 1  and RT 2  are held by the tables  10   a - 15   a . Materials of the tables  10   a - 15   a  for holding the substrates may be selected depending on the type of processing solution in the processing tanks. Fluorine contained resin such as Teflon® or thermoplastic resin such as PVC, PVDF are normally selected for the processing tanks that accommodate a processing solution at a temperatures lower than 100° C., and quartz or a material which is formed by applying fluorine contained resin on the surface of quartz is used for the processing tanks that accommodate a processing solution at a temperature higher than 100° C.  
         [0049]    As shown in FIG. 5, the fastener washing tanks  8  and  9 , which correspond to fastener washing means, are devices for washing extremities of a substrate fasteners  5   c  of the substrate transporting devices (shown in FIG. 6), on which the processing solution is attached, in order to remove the attached processing solution before proceeding to the fastening operation for the next lot of substrates. The fasteners are lowered into the fastener washing tanks (a pure overflow tank provided with a rapid discharging function)  8  and  9  and soaked therein, where the processing solution attached on the fastener is washed by pure displacement, and then lifted up at a velocity of 1-20 mm/sec for removing pure water attached on the surfaces of the fasteners. The substrate transporting devices RT 1  and RT 2  are absolutely required to be washed at their substrate fasteners in the fastener washing tanks  8  and  9  each time after they have unloaded the substrates from the processing tank which contains the processing solution. The fastener washing tank is provided for each substrate transporting device. The substrate transporting device RT 1  uses the fastener washing tank  8 , and the substrate transporting devices RT 2  and RT 3  use the fastener washing tank  9 . Washing of the substrate fasteners is not required after the transportation of the substrates from the processing tanks for overflow rinsing or quick damp rinsing, which do not use the processing solution.  
         [0050]    The substrate transporting devices RT 1 , RT 2 , and RT 3  are disposed on the identical transporting track  4  and are operated as follows. The substrates in the buffer  6  transported by the shuttle  3  are held and moved along the transporting track  4  which is provided along the processing tank, and transported to the substrate delivery position of the processing tank. Then, the substrates which has processed in the processing tanks are held at the substrate delivery position and transported to the next processing tank. The substrates which are dried in a drying tank are then transported to the processed substrate unloading unit  36 . An arrow shown in FIG. 5 represents a route along which the substrates are transported.  
         [0051]    As shown in FIG. 6, the substrate transporting devices RT 1 , RT 2 , RT 3  each include a laterally movable portion  5   a  movable freely along the transporting track  4 , a vertically movable portion  5   b  movable in the vertical direction, and the substrate fastener  5   c  for fastening, holding, and releasing a substrate  40 .  
         [0052]    The laterally movable portion  5   a  of the substrate transporting device is movable on a rack which corresponds to the transporting track  4  by a pinion driven by a pulse motor or the like. The substrate transporting device may be moved to a predetermined position by applying the number of pulses and the direction of movement which corresponds to the amount of movement to the pulse motor via a pulse motor driver.  
         [0053]    The vertically movable portion  5   b  of the substrate transporting device moves upward and downward by rotating a ball screw by the pulse motor or the like. The substrate fastener  5   c  mounted at the extremity of the vertically movable portion  5   b  to the top dead center and the bottom dead center (substrate delivery positions) can be moved by applying the number of pulses and the vertical direction as the amount of vertical movement to the pulse motor via the pulse motor driver. The substrate fastener  5   c  for fastening, holding, and releasing the substrates  40  is capable of fastening, holding, and releasing the substrates  40  by moving the extremities thereof in the direction shown in FIG. 6 by the motor. The substrate fastener  5   c  is provided with a substrate sensor (a substrate presence detecting sensor) for detecting failure of fastening or failure of releasing of the substrate  40 . The extremities of the substrate fastener  5   c  is constructed of Teflon® which is a material with less hard than material of the substrates to be processed.  
         [0054]    [0054]FIGS. 7A to  7 E show the delivery operation for delivering the substrates to the processing tank of the substrate transporting device. As shown in FIG. 7A, the substrate fastener  5   c  of the substrate transporting device moves downward until the position just before the table  10   a  of the processing tank in a state of holding the substrate  40 . Subsequently, the substrate transporting device moves downward at a slow speed. When the substrates come into contact with the table  10   a  as shown in FIG. 7B, the downward movement of the substrate fastener  5   c  stops. The state in which the substrate fastener  5   c  holds the substrates  40  at this moment is shown in FIG. 7E in an enlarged manner. As shown in FIG. 7E, even when the substrate fastener  5   c  is moved further downward after the substrates comes into contact with the table  10   a , since the substrates  40  are not constrained in the upward direction by the substrate fastener  5   c , the substrates slide upward along the substrate fastener  5   c . Therefore, the substrates are prevented from becoming damaged. After placing the substrates on the table  10   a , as shown in FIG. 7C, the substrate fastener  5   c  is rotated in the directions indicated by arrows, and release the substrates from being held. Then, as shown in FIG. 7D, the substrate fastener  5   c  is moved upward.  
         [0055]    The transporting track  4  shown in FIG. 5 is provided along the processing tanks  10 - 15 , so that the substrate transporting devices can move freely along the transporting track  4 . The transporting track  4  is provided with the rack, so that the substrate transporting devices RT 1 , RT 2 , and RT 3  can move freely along the transporting track  4  by the pinion of the laterally movable portion  5   a  of the substrate transporting device.  
         [0056]    The shuttle  3  shown in FIG. 5 is a device for receiving the unprocessed substrates, which are stored in the cassette transported from the stocker  30  and taken from the cassette by the unprocessed substrate loading unit  35  by being fastened altogether, from the substrate hoisting unit  23  and transporting them to the substrate lowering unit  24 . As shown in FIG. 5, the shuttle  3  is disposed in parallel with the transporting track  4  at the position higher than the substrate transporting devices RT 1 , RT 2 , and RT 3 , so as to be capable of transporting the substrates to the substrate lowering unit  24 . The shuttle  3  can be operated independently of the transporting track  4 . Therefore, the unprocessed substrate from the stocker can be transported to the first processing tank, and thus the substrate transporting devices RT 1 , RT 2 , and RT 3  can work only for transporting the substrates between the processing tanks.  
         [0057]    The operation of the substrate transporting device in the substrate processing apparatus  1  will now be described. FIG. 8 is a drawing showing a movable range of the substrate transporting devices RT 1 , RT 2 , and RT 3  of the substrate processing apparatus  1  on the transporting track  4 . As shown in FIG. 8, the substrate transporting device RT 1  is capable of moving form the buffer  6  to the last processing tank  15 . The substrate transporting device RT 2  is capable of moving from the first processing tank  10  to the drying tank  20 . The substrate transporting device RT 3  is capable of moving from the fastener washing tank  9  to the processed substrate unloading unit  36 . The substrate transporting device RT 1  and the substrate transporting device RT 2  can commonly be moved from the first processing tank  10  to the last processing tank  15 . However, since the transporting track  4  is shared, the substrate transporting device RT 1  is capable of moving to the n-1 th  processing tank, which is immediately before the processing tank at which the substrate transporting device RT 2  is currently located (the position where the n th  processing tank is located).  
         [0058]    Provided between the buffer  6  and the first processing tank  10  is the first fastener washing tank  8 . The first fastener washing tank  8  is a fastener washing tank specifically provided for washing the substrate fastener  5   c  of the substrate transporting device RT 1 .  
         [0059]    Provided between the last processing tank  15  and the drying tank  20  is the second fastener washing tank  9 . The second fastener washing tank  9  is a fastener washing tank specifically provided for washing the substrate fastener  5   c  of the substrate transporting device RT 2  and the substrate transporting device RT 3 .  
         [0060]    Normally, the substrate transporting device RT 1  waits on the first fastener washing tank  8 , the substrate transporting device RT 2  waits on the second fastener washing tank  9 , and the substrate transporting device RT 3  waits on the processed substrate unloading unit  36 .  
         [0061]    Accordingly, when one of these three substrate transporting devices RT 1 , RT 2 , and RT 3  is operated, for example, when only the substrate transporting device RT 2  is operated, and the remaining two substrate transporting devices RT 1  and RT 3  are waiting, the substrate transporting device R 2  can move within the region from the first processing tank  10  to the drying tank  20 . When the substrate transporting devices RT 1  and RT 2  are operated simultaneously, the substrate transporting device RT 1  can move to the position immediately before the substrate transporting device RT 2 .  
         [0062]    Subsequently, loading of the substrates to the processing tank, unloading of the substrates from the processing tank, and movement among the processing tanks of the substrate transporting devices will be described.  
         [0063]    When loading the substrate into the processing tank by the substrate transporting device RT 1 , the substrates are held by the substrate fastener  5   c , and then the substrate fastener  5   c  is lifted to the top dead center after the substrates are fastened. When they reached the top dead center, they are moved along the transporting track  4  and stops exactly above the processing tank. The processing tank opens its lid located on top thereof, and moves the lifter upward to the substrate delivery position. The substrate transporting device RT 1  moves the substrate fastener  5   c  downward to the position immediately before the substrate delivery position of the lifter. Then, the substrate fastener  5   c  is moved additionally 2-5 mm downward from the substrate delivery position of the lifter, places the substrates on the lifter in a state of fastening the substrates, and stops. At this time, the substrates are held by both of the substrate fastener  5   c  and the lifter. After the substrate fastener has stopped, the extremities of the substrate fastener  5   c  are opened, and deliver the substrates to the lifter completely. The substrate transporting device RT 1  moves the substrate fastener  5   c  upward to the top dead center. After the extremities of the substrate fastener  5   c  is opened, the fact that the substrates to be processed are placed on the lifter is checked by the substrate presence detecting sensor provided on the lifter, and upward movement of the substrate transporting device RT 1  and downward movement of the lifter are performed simultaneously. After termination of the upward movement of the substrate transporting device RT 1 , the fact that no substrate to be processed is left in the fastener  5   c  is checked by the substrate presence detecting sensor provided on the substrate transporting device RT 1 . After completion of the downward movement of the lifter, the lid on top of the processing tank is closed and processing of the substrates is carried out.  
         [0064]    When the substrate transporting devices RT 1  and RT 2  deliver the substrates to the lifter, the substrate fastener  5   c  is moved upward, and when it reached the top dead center, it is moved along the transporting track  4 , is stopped exactly above the processing tank, and then, is moved downward to the position immediately before the substrate delivery position of the lifter. However, the substrate processing apparatus according to the invention is constructed in such a manner that the substrate fastener  5   c  can be moved downward to the position immediately before the substrate delivery position of the lifter while the substrate transporting devices RT 1  and RT 2  are moving to the processing tank to which the substrates are delivered, and the lifter can be moved upward to the substrate delivery position while the substrate transporting devices RT 1  and RT 2  are moving. By overlapping the operation of the substrate transporting device and the lifter, the time period required for transporting the substrates may be reduced.  
         [0065]    After completion of processing the substrates, the processing tank opens the lid on top thereof and moves the substrates upward to the substrate delivery position by the lifter. The substrate transporting device RT 1  moves downward to the substrate delivery position in a state in which the extremities of the substrate fastener  5   c  is opened. Then, presence of the substrates on the lifter is checked. When there are substrates on the lifter, the substrates are fastened. Subsequently, the substrate transporting device RT 1  moves the substrate fastener  5   c  upward. At this time, whether or not the substrates are properly fastened is checked by the substrate presence detecting sensor provided on the lifter and the substrate presence detecting sensor provided on the substrate transporting device RT 1  before moved upward to the top dead center. The processing tank moves the lifter downward and closes the lid. Loading of the substrates to the processing tank, unloading of the substrates from the processing tank, and movement among the processing tanks of the substrate transporting devices RT 2  and RT 3  are the same as the substrate transporting device RT 1 .  
         [0066]    The stocker, the unprocessed substrate loading unit, the shuttle, and the transporting path for the substrates in the substrate processing apparatus described above are shown in FIG. 9. As shown in FIG. 9, the unprocessed substrates stored in the cassette are loaded to the stocker  30 , are transferred from the stocker  30  to the unprocessed substrate loading unit  35 . Then all the substrates are fastened altogether and taken out from the cassette, are transferred to the shuttle  3  by the substrate hoisting unit  23 , and are delivered to the shuttle  3 . The shuttle  3  transfers the substrates to the substrate lowering unit  24 , and delivers them to the substrate lowering unit  24 . The substrate lowering unit  24  moves downward to the delivery position of the buffer  6  while holding the substrates and delivers the substrates to the buffer  6 .  
         [0067]    The substrate transporting device RT 1  moving along the transporting track  4  fastens the substrates in the buffer  6  altogether, moves upward to the top dead center. After reaching the top dead center, the substrate transporting device RT 1  moves to the position exactly above the first processing tank  10 . After completion of movement, the substrate transporting device moves downward to the substrate delivery position of the processing tank and delivers the substrates to the lifter. Upon reception of the substrates, the lifter moves downward, and after completion of downward movement, processing is carried out in the processing tank. After completion of processing, the lifter moves upward to the substrate delivery position, and delivers the substrates to the substrate transporting device RT 1  or RT 2 . In the same manner, the substrates are transported in sequence by the substrate transporting device RT 1  or RT 2  to the processing tank, where processing is carried out. The substrates having dried in the drying tank  20  are transferred to the processed substrate unloading unit  36  by the substrate transporting device RT 3  and stored in the cassette by the processed substrate unloading unit  36 . The substrates stored in the cassette are loaded into the stocker  30 , and delivered to the next process by the stocker  30 .  
         [0068]    Subsequently, control of the substrate transporting device in the substrate processing apparatus  1  will be described. In the first place, processing conditions and transporting conditions in the substrate processing apparatus  1  are set. The processing conditions and the transporting conditions in the substrate processing apparatus include, for example, processing time assigned for each processing tank, the type of processing solution, transporting time of the substrate transporting device, and operating time of the lifter. After these processing conditions and transporting conditions are entered, processing operation including control of the substrate transporting device is scheduled by the scheduler (software) of the computer built-in the substrate processing apparatus  1 . Timings of the operation of each substrate transporting device are determined according to the schedule. The computer built in the substrate processing apparatus  1  stores the substrate transportation sharing conditions which determines the sharing condition when transportation of the substrate occurs at the plurality of processing tanks simultaneously according the scheduling data prepared by the scheduler. The substrate transportation sharing conditions include such conditions that transportation of the substrates from the buffer  6  to the first processing tank  10  is carried out by the substrate transporting device RT 1 , transportation of the substrates from the drying tank  20  to the processed substrate unloading unit  36  is carried out by the substrate transporting device RT 3 , and in the case of simultaneous transportation of the substrates at the nth processing tank and the tanks before nth processing tank, transportation of the substrates in the nth processing tank is carried out by the substrate transporting device RT 2 , and transportation of the substrates in the tanks before the nth processing tanks is carried out by the substrate transporting device RT 1 .  
         [0069]    [0069]FIG. 10 is a flowchart for preparing a control sequence for the substrate processing apparatus  1  by the scheduler. As shown in FIG. 10, in a first place, data on processing conditions and transporting conditions relating the number of processing tanks to be installed, the processing time assigned for each processing tank, the types of processing solutions, transporting time of the substrate transporting device, and the operating time of the lifter are entered via an input device such as a keyboard, or by measurement of the transporting time, and the operating time of the lifter (teaching) (Step S 1 ). The computer prepares a schedule of processing based on the entered data (Step S 2 ). During scheduling, times to start loading and unloading of the substrates into/from the respective tank are calculated based on data on processing time assigned for each processing tank and the types of processing solutions in the processing tanks. Whether or not washing of the fastener of the substrate transporting device is determined based on the type of the processing solution in the processing tank. Accordingly, time to start processing and time to terminate processing in every processing tank, and timing of loading and unloading of the substrates for each processing tank of the substrate transporting device are determined.  
         [0070]    Subsequently, whether or not the operations of the substrate transporting devices are overlapped is determined from timing of loading and unloading of the substrate transporting device (Step S 3 ). When the operations of the substrate transporting devices are not overlapped, the procedure goes to Step S 8 . When the operations of the substrate transporting device are overlapped, the procedure goes to Step S 5  (Step S 4 ), where the substrate transportation sharing conditions stored in the storage are referenced (Step S 5 ), and whether or not transportation of the substrates may be well shared among the substrate transporting devices RT 1 , RT 2 , and RT 3  is checked. When it maybe well shared, the procedure goes to Step S 8 . When it cannot be well shared, the procedure goes to Step S 7  (Step S 6 ), timing of loading the substrate prepared by the schedule is changed (Step S 7 ), and the procedure goes to Step S 3 . When it is determined that the substrate transporting devices can manage, the schedule is fixed (Step S 8 ). Data on the fixed schedule is transferred to the control unit of the substrate processing apparatus  1  (Step S 9 ), and then the substrate processing apparatus  1  starts processing (Step S 10 ). With the procedures described above, the substrates in the buffer  6  are transported to the first processing tank by the substrate transporting device RT 1 , where processing is started.  
         [0071]    Timing chart shown in FIG. 11 shows processing of the substrates in each processing tank according to the control sequence of the substrate processing apparatus  1  prepared by the scheduler in chronological order. Squares shown in the columns of the substrate transporting devices RT 1 , RT 2 , and RT 3  show the substrate transporting operation, and black squares represent washing operation of the substrate fastener in the fastener washing tank. As shown in FIG. 11, when transportation of the substrates occurred simultaneously, transportation of the substrates may be carried out in sequence without delay by allowing the substrate transporting devices RT 1 , RT 2 , and RT 3  to share the operation. In comparison with the case in which a single substrate transporting device is provided, it is not necessary to delay loading of the substrates into the washing tank, and thus improvement of the throughput is achieved. In addition, since the unprocessed substrates are transported by the shuttle and thus the substrate transporting devices must simply perform transportation among the processing tanks, improvement of the throughput may be achieved.