Abstract:
A work conveying system eliminates gravitational deflection of an extended articulated arm of a vertical mover. The conveying system includes a horizontal mover which carries the vertical mover and a work holder for delivering a workpiece to various apparatuses without dislocation. In conveying a workpiece horizontally, the vertical mover folds compactly to minimize air disturbance. Plural arm elements of the articulated arm overlap and are connected together in an alternate manner at their respective end portions, and the articulated arm is extended and contracted by pivotal movement of the arm elements, driven by a single drive unit. The horizontal mover is movable in an arbitrary horizontal plane within the upper ceiling space within the clean room. Shafts in the articulated arm and a rotary drive unit in the work holder have hollow interiors which are intercommunicated and at a negative pressure.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a work conveying system for a clean room and more particularly to a work conveying system which conveys a work to various processing apparatuses while circulating from one to another processing apparatuses in a production line within a clean room for the production of, for example, semiconductor components, liquid crystal display panels, medical supplies, chemicals, and processed foods.  
           [0003]    2. Description of the Prior Art  
           [0004]    In a semiconductor integrated circuit or a liquid crystal display panel, the deposition of dust results in a lowering of product yield. It is desirable that medical supplies, chemicals, and processed foods be produced in a sterile hygienic environment. Therefore, in a wide variety of fields including those products, intra-clean room production lines are in operation and various techniques are now under development with respect to various processing chambers installed within a clean room and work conveying systems.  
           [0005]    As to the work conveying system, the present applicant has previously invented a work conveying system and applied for a patent (see Japanese Patent Laid Open No. 243808-2000) which system is provided with a moving means able to move a work holding means in arbitrary three-dimensional directions in an upper ceiling space within a clean room. In this work conveying system, a pair of horizontal fixed guide rails are laid in parallel in the ceiling space and one or plural horizontal traveling guide rails are mounted between the paired fixed guide rails so that they can travel along the fixed guide rails. Also, a travel body adapted to travel along the traveling guide rail(s) is provided on the traveling guide rail(s), and a horizontal moving means is constituted by the fixed guide rails, the traveling guide rail(s) and the travel body. The travel body is provided with a vertical moving means which can cause the work holding means to move up and down. Further, a three-dimensional moving means is constituted by a combination of the vertical moving means and the horizontal moving means.  
           [0006]    [0006]FIGS. 10 and 11 show such a vertical moving means  013 , in which FIG. 10( 1 ) is a front view showing a raised state of the vertical moving means, FIG. 10( 2 ) is a side view in vertical section thereof, FIG. 11( 1 ) is a front view showing a lowered state thereof, and FIG. 11( 2 ) is a side view in vertical section thereof. As shown in these figures, the vertical moving means  013  is constituted by an articulated arm having three arms  016 ˜ 018 . With pivotal movements of the first to third arms  016 ˜ 018 , which are a first start-end arm, a second arm, and a third terminal-end arm, a work holding means  011  fixed to the third terminal-end arm  018  is moved up and down on a vertical line. The work holding means  011  makes delivery of a work (a hermetically seal container) between it and each various processing apparatuses. In this case, the articulated arm has such a structure as shown in FIGS.  10 ( 2 ) and  11 ( 2 ) in which the arms  016 ˜ 018  are stacked in multiple stages.  
           [0007]    The pivotal movements of the arms  016 ˜ 018  are performed respectively by a motor  021   a  disposed within a travel body  015 , a motor  021   b  disposed within the first start-end arm  016 , and a motor  021   c  disposed within the second arm  017 . Though not shown in detail, the interiors of the arms  016 ˜ 018  and the interior of the travel body  015  are in communication and are supplied with a negative pressure so that dust generated in those interiors is sucked and discharged in one direction.  
           [0008]    Since this work conveying system is constructed as above, an area for work conveyance is not required on the floor surface of the clean room and the interior of the clean room can be utilized effectively. Therefore, for the same equipment, a required volume of the clean room can be diminished and it is possible to reduce the equipment cost and operation cost of the clean room. Besides, the installing position and direction of apparatuses such as processing chambers installed within the clean room are difficult to be restricted and it is possible to select an optimal arrangement. Also in case of adding a new apparatus such as a processing chamber or in case of changing the arrangement of apparatuses such as processing chambers, it is possible to freely select their arrangement and installing direction. Thus, it is also possible to reduce the cost for change in arrangement or for an increase of such apparatuses as processing chambers. Further, it is possible to move the work holding means  011  linearly from a certain position to another position, whereby the work processing efficiency in the clean room is improved. There are attained various such excellent effects.  
           [0009]    However, in the work conveying system in question, a torque load based on arm weight is imposed on the mounting portion for mounting to the horizontal moving means and a deflection caused by extension of the articulated arm is not negligible. Further, in the articulated arm of this structure, the pivotal movement of the first start-end arm  016  relative to the horizontal moving means is performed by operation of a motor  021   a  provided on the horizontal moving means (travel body  015 ) side and thus this structure is difficult to be sealed. In addition, there are used dedicated motors  021   a ˜ 021   c  as drive sources for pivotal movements of the first to third arms  016 ˜ 018  respectively and the structure using such many drive sources is apt to generate dust.  
         SUMMARY OF THE INVENTION  
         [0010]    It is an object of the present invention to solve the above-mentioned problems involved in the conventional work conveying system and provide a work conveying system capable of eliminating a gravitational deflection induced upon extension of the articulated arm in the vertical moving means, permitting the work holding means to deliver a work to each processing apparatuses without dislocation, permitting smooth extension and contraction of the articulated arm, permitting the vertical moving means to be folded compactly when conveying a work horizontally, thereby minimizing the disturbance of an air flow, and being easy to be sealed.  
           [0011]    It is another object of the present invention to provide a work conveying system which, in case of a work being a wafer or a reticle, can convey the wafer or reticle each individually and rapidly to a predetermined processing apparatus and can thereby improve the working efficiency.  
           [0012]    For solving the foregoing problems, in one aspect of the present invention, there is provided a work conveying system comprising a work holding means for holding a work, a horizontal moving means for moving the work holding means horizontally in an upper ceiling space within a clean room, and a vertical moving means provided in the horizontal moving means and constituted by an articulated arm, the articulated arm being adapted to extend and contract, thereby causing the work holding means to move up and down, the work being conveyed to the plural processing apparatuses while circulating among the processing apparatuses within the clean room, wherein plural arms as constituents of the articulated arm are overlapped and connected together successively in an alternate manner at respective end portions, and the articulated arm is extended and contracted with pivotal movements of the arms.  
           [0013]    Since the invention in the above first aspect is constructed as above, there can be attained the following effects.  
           [0014]    In the work conveying system installed within a clean room, the vertical moving means provided in the horizontal moving means is constituted by an articulated arm, the plural arms as constituents of the articulated arm are overlapped and connected successively in an alternate manner at respective end portions, and the articulated arm is adapted to extend and contract with pivotal movements of the arms, so that there is no fear of centroid deviation of the articulated arm and the weight balance of the entire arm becomes stable, with little gravitational deflection even upon extension of the articulated arm (descent of the vertical moving means). Consequently, it becomes possible for the work holding means to deliver a work to each of various processing apparatuses without dislocation, the extension and contraction of the articulated arm are performed smoothly, and when conveying a work horizontally, the vertical moving means can be folded compactly to minimize the disturbance of an air flow. Besides, a torque based on the weight of the entire all and the work weight does not occur, thus permitting a stable conveyance of a work in the horizontal direction.  
           [0015]    In a second aspect of the present invention there is provided a work conveying system comprising a work holding means for holding a work, a horizontal moving means for moving the work holding means horizontally in an upper ceiling space within a clean room, and a vertical moving means provided in the horizontal moving means and constituted by an articulated arm, the articulated arm being adapted to extend and contract, thereby causing the work holding means to move up and down, allowing the work to be delivered between the work holding means and each of plural processing apparatus, the work being conveyed to the plural processing apparatuses while circulating among the processing apparatuses within the clean room, wherein the articulated arm in the vertical moving means has three or more arms, the vertical moving means has a single drive source and has a structure having a predetermined pivoting ratio among the arms, and the articulated arm is extended and contracted by operation of the drive source and by consequent pivotal movements of the arms.  
           [0016]    In the second aspect constructed as above there can be obtained the following effect.  
           [0017]    In the work conveying system installed within a clean room, the vertical moving means provided in the horizontal moving means is constituted by an articulated arm comprising three or more arms, the vertical moving means has a single drive source and a structure having a predetermined pivoting ratio among the arms, and the articulated arm is extended and contracted linearly by operation of the drive source and consequent pivotal movements of the arms, so that by a combined use of a single drive source and three or more arms in the vertical drive means the arms are interlocked with one another, ensuring a smooth motion free of impact.  
           [0018]    In a third aspect of the present invention there is provided in combination with the above first aspect, a work conveying system wherein the vertical drive means is constituted by an articulated arm having three or more arms, the vertical drive means has a single drive source and a predetermined pivoting ratio among the arms, and the articulated arm is extended and contracted by operation of the drive source and by consequent pivotal movements of the arms.  
           [0019]    According to this construction, by a combined use of a single drive source and three or more arms in the vertical moving means, the arms are interlocked with one another and there is obtained a smooth impact-free motion.  
           [0020]    In a fourth aspect of the present invention there is provided, in combination with the above first or second aspect, a work conveying system wherein in the upper ceiling space within the clean room the horizontal moving means is movable in an arbitrary horizontal plane.  
           [0021]    According to this construction, following the movement of the horizontal moving means, the work holding means is also made movable in the upper ceiling space within the clean room and in an arbitrary horizontal plane, so that the installing position and direction of processing apparatuses such as processing chambers installed within the clean room are not restricted and it is possible to select an optimal arrangement. Moreover, also in case of adding a new apparatus such as a new processing chamber or in case of changing the arrangement of those apparatuses, it is possible to select their arrangement and installing direction freely and hence possible to reduce the cost for changing the arrangement of those apparatuses or for an increase of new such apparatus. Further, it becomes possible to move the work holding means linearly from a certain position to another position and therefore the work processing efficiency within the clean room is improved.  
           [0022]    In a fifth aspect of the present invention there is provided, in combination with the above second aspect, a work conveying system wherein in the vertical moving means, the pivotal movement of a first start-end arm relative to the horizontal moving means is performed by operation of a motor disposed on the first arm side.  
           [0023]    According to this construction, the sealing of dust generated from the motor as a single drive source and that of dust generated from the structure having a predetermined pivoting ratio can all be done on the arm side and thus it becomes easy to effect sealing. Besides, by utilizing an empty space included in the internal space of the first arm, it is possible to accommodate the motor as a single drive source therein, thus affording a work conveying system of a compact structure.  
           [0024]    In a sixth aspect of the present invention there is provided, in combination with the above first or second aspect, a work conveying system wherein joint shafts in the articulated arm are of a hollow structure and internal spaces of the arms are intercommunicated and supplied with a negative pressure.  
           [0025]    According to this construction, the structure for the discharge of dust generated in the internal space of each of the arms which constitute the articulated arm is simplified, the discharge of the dust becomes easier, the amount of dust leaking into the clean room is greatly decreased, and it becomes easy to maintain the clean room at a required degree of cleanness.  
           [0026]    Further, in a seventh aspect of the present invention there is provided, in combination with the above first or second aspect, a work conveying system wherein the work holding means is provided with a work rotation drive unit so that the work can be rotated in a horizontal plane.  
           [0027]    According to this construction, in addition to conveyance of the work in a three-dimensional space, it is also possible to make a rotational direction/posture control for the work in a horizontal plane and possible to accurately establish a rotational direction at the time of loading the work, thus making it possible to fully cope with high-degree of requirements for the work conveying system.  
           [0028]    In an eighth aspect of the present invention there is provided, in combination with the above sixth aspect, a work conveying system wherein the work holding means is provided with a work rotation drive unit for rotating a work holding unit in the work holding means so that the work can be rotated in a horizontal plane, the work rotation drive unit having a hollow structure and being in communication with internal spaces of the arms so that dust generated from the drive unit is sucked into the internal spaces of the arms by virtue of the negative pressure.  
           [0029]    According to this construction, in addition to conveyance of the work in a three-dimensional space, it is also possible to make a rotational direction/posture control for the work in a horizontal plane and possible to accurately establish a rotational direction at the time of loading the work, thus making it possible to fully cope with high-degree of requirements for the work conveying system. Moreover, the structure for the discharge of dust generated in the internal space of the work rotation drive unit is simplified, the discharge of the dust becomes easy, the amount of dust leaking into the clean room is greatly decreased, and it becomes still easier to maintain the degree of cleanness in the clean room.  
           [0030]    In a ninth aspect of the present invention there is provided, in combination with any of the above first to eighth aspects, a work conveying system wherein the work is a wafer or a reticle, and plural such wafers or reticles are received within a work container and are held in this state by the work holding means.  
           [0031]    According to this construction, plural wafers or reticles as works are accommodated in a hermetically sealed state within the work container and in this state can be conveyed within the clean room, so that it is possible to easily attain a high-degree of cleanness required for the works.  
           [0032]    In a tenth aspect of the present invention there is provided a work conveying system comprising a work holding means for holding a work alone such as a wafer or a reticle directly, a horizontal moving means for moving the work holding means horizontally in an upper ceiling space within a clean room, and a vertical moving means provided in the horizontal moving means, the vertical moving means causing the work holding means to move up and down so that the work alone is delivered between the work holding means and each of plural processing apparatuses, the work alone being conveyed to the plural processing apparatuses while circulating among the processing apparatuses within the clean room, wherein an identification mark for recognizing processing steps which the work alone is to follow is affixed to the work, and the work holding means is provided with a detector for detecting the identification mark.  
           [0033]    In the tenth aspect constructed as above, there can be attained the following effect.  
           [0034]    An identification mark for recognizing processing steps which a work alone is to follow is affixed to the work which is a wafer or a reticle and the work holding means which holds work alone directly is provided with a detector for detecting the identification mark. In holding the work alone, the work holding means detects the identification mark affixed to the work alone and transmits the detected signal to a controller in the work conveying system, whereby the work conveying system can convey the work alone rapidly to each processing apparatus in accordance with a preset sequence and subject it to predetermined processings, in a three-dimensional space within a clean room. Consequently, the working efficiency of the work conveying system is improved to a remarkable extent.  
           [0035]    Further, in an eleventh aspect of the present invention there is provided a work conveying system comprising a work holding means for holding a work alone such as a wafer or a reticle directly, a horizontal moving means for moving the work holding means horizontally in an upper ceiling space within a clean room, and a vertical moving means provided in the horizontal moving means, the vertical moving means causing the work holding means to move up and down, allowing the work alone to be delivered between the work holding means and each of plural processing apparatuses, the work alone being conveyed to the plural processing apparatuses while circulating among the processing apparatuses within the clean room, wherein an identification mark for recognizing processing steps which the work alone is to follow is affixed to the work, and an identification mark detecting device provided with a detector for detecting the identification mark is disposed within the clean room.  
           [0036]    In the eleventh aspect constructed as above, there can be attained the following effect.  
           [0037]    An identification mark for recognizing processing steps which a work alone such as a wafer or a reticle follows is affixed to the work alone and an identification mark detecting device provided with a detector for detecting the identification mark is disposed within a clean room. The identification mark detecting device detects the identification mark affixed to the work alone which has been conveyed up to the installed position of the detecting device and then transmits the detected signal to a controller in the work conveying system, whereby in a three-dimensional space within the clean room the work conveying system can convey the work alone to each of processing apparatuses rapidly in accordance with a predetermined sequence and subject it to predetermined processings. Consequently, the working efficiency of the work conveying system is greatly improved. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0038]    [0038]FIG. 1 is a perspective view of a production line in a clean room to which a work conveying system is applied according to an embodiment (first embodiment) of the invention defined in the foregoing first to ninth aspects;  
         [0039]    [0039]FIG. 2 is a perspective view of a production line in a clean room according to a modification, which is similar to FIG. 1;  
         [0040]    [0040]FIG. 3 is a front view showing a raised state of a vertical moving means provided in the work conveying system;  
         [0041]    [0041]FIG. 4 is a side view thereof;  
         [0042]    [0042]FIG. 5 is a front view showing a lowered state of the vertical moving means;  
         [0043]    [0043]FIG. 6 is a side view thereof;  
         [0044]    [0044]FIG. 7 is a front view showing a raised state of a vertical moving means provided in a work conveying system according to another embodiment (second embodiment) of the invention defined in the foregoing tenth aspect, and corresponds to FIG. 3;  
         [0045]    [0045]FIG. 8 is a plan view of a work held by a work holding means provided in the work conveying system;  
         [0046]    [0046]FIG. 9 is a front view showing a state in which an identification mark detecting device is detecting an identification mark, the identification mark detecting device being installed within a clean room to which a work conveying system according to a further embodiment (third embodiment) of the invention defined in the foregoing eleventh aspect is applied;  
         [0047]    [0047]FIG. 10 shows a vertical moving means provided in a conventional work conveying system, in which FIG. 10( 1 ) is a front view showing a raised state of the vertical moving means and FIG. 10( 2 ) is a side view in vertical section thereof; and  
         [0048]    [0048]FIG. 11 shows the vertical moving means provided in the conventional work conveying system, in which FIG. 11( 1 ) is a front view showing a lowered state of the vertical moving means and FIG. 11( 2 ) is a side view in vertical section thereof. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0049]    An embodiment (first embodiment) of the present invention defined in the foregoing first to ninth aspects will be described below, which are shown in FIGS.  1  to  6 .  
         [0050]    [0050]FIG. 1 is a perspective view of a production line in a clean room to which a work conveying system according to the first embodiment is applied, FIG. 2 is a perspective view of a production line a clean room according to a modification, which is similar to FIG. 1, FIG. 3 is a front view showing a raised state of a vertical moving means provided in the work conveying system, FIG. 4 is a side view thereof, FIG. 5 is a front view showing a lowered state of the vertical moving means, and FIG. 6 is a side view thereof.  
         [0051]    In a production line  1  within a clean room to which the work conveying system of this first embodiment is applied, as shown in FIG. 1, plural processing chambers (processing apparatuses)  3  are arranged side by side in two rows on a floor surface  2  in the clean room, with an interface device  4  being attached to each processing chamber  3 .  
         [0052]    The processing chambers  3  are apparatuses for performing different processings for works one after another. However, taking tact time balance in work processing into account, a plurality of same processing chambers may be included in the production line. For example, the processing chambers  3  are semiconductor wafer processing apparatuses for conducting such processings as the application of resist, exposure, development, ion implantation, annealing, and sputtering. Although the following description is now provided with such processings for a semiconductor wafer in mind, the work conveying system in question is also applicable to reticle processing apparatuses.  
         [0053]    The interface devices  4  constitute buffer spaces for isolating the processing chambers  3  and the clean room from each other. The delivery of works in each processing chamber  3  is executed through the associated interface device  4 . A work inlet/outlet  5  in each interface device  4  is hermetically sealed except when loading or unloading a work.  
         [0054]    Adjacent processing chambers  3  and interface devices  4  are arranged through a minimum maintenance area required for works which maintenance personnel or operator personnel performs. Thus, the floor area of the clean room is minimized to make the most use of the clean room and attain an efficient conveyance of works by the work conveying system  10 , which will be described later. But it is not always necessary that the processing chambers  3  be arranged in plural rows, nor is specified in which direction a front side (the side where each interface device  4  is provided) should face. A certain degree of random arrangement is allowed.  
         [0055]    In an upper space within the clean room is installed the work conveying system  10  for conveying a hermetically sealed container (work container)  6  to the processing chambers  3  in accordance with a predetermined processing sequence, the container  6  containing plural sheets of works (wafers or reticles). In order to maintain a high-degree of cleanness required, the works are conveyed in a hermetically sealed state within the container  6 . On the floor surface  2  is provided a space for the travel of work carriers  7 . When a work carrier  7  receives the hermetically sealed container  6  which has been conveyed from outside the clean room, the work carrier  7  travels up to a predetermined position along a rail which is laid there, and delivers the container  6  to the work conveying system  10 .  
         [0056]    The work conveying system  10  is provided with work holding means  11  for holding the hermetically sealed container  6 , horizontal moving means  12  for moving the work holding means  11  horizontally in an upper ceiling space within the clean room, and vertical moving means  13  constituted by an articulated arm and provided in the horizontal moving means  12 . In the vertical moving means  13 , the articulated arm is extended and contracted to raise and lower the work holding means  11 , thereby delivering works between the work holding means  11  and each of the processing chambers  3 . A three-dimensional moving mechanism is constituted by both horizontal moving means  12  and vertical moving means  13 .  
         [0057]    As shown in FIG. 1, the horizontal moving means  12  comprises a pair of horizontal fixed guide rails  14  which are laid in parallel in the upper ceiling space within the clean room and, travel bodies  15  installed respectively on the fixed guide rails  14  and adapted to travel along the guide rails  14 . Though not shown in detail, a drive mechanism for each travel body  15  has a motor integral with the travel body  15  and received within the associated fixed guide rail  14 , and a roller fixed onto a rotary shaft of the motor is adapted to roll along an inner wall surface of the fixed guide rail  14 , whereby the travel body  15  travels along the fixed guide rail. A base end portion of the vertical moving means  13  (a base end portion of the first start-end arm  16 ) is connected pivotably to the travel body  15  and is adapted to travel together with the travel body  15 .  
         [0058]    The horizontal moving means  12  may be modified as shown in FIG. 2. In the horizontal moving means  12 , a pair of horizontal fixed guide rails  14  are disposed in parallel in the upper ceiling space of the clean room and one or plural traveling guide rails  28  are mounted between the fixed guide rails  14 , and a travel body  15  adapted to travel along each traveling guide rail  28  is carried on the same guide rail  28 . Thus, in this modification, the horizontal moving means  12  can move in the upper ceiling space within the clean room and in an arbitrary horizontal plane sandwiched in between the pair of fixed guide rails  14 . By moving the vertical moving means  13  and the working holding means  11  linearly from a certain position up to another position on the opposite side with respect to the central passage, the delivery of works can be done between the work holding means  11  and each processing chamber  3 . The spacing between the pair of horizontal fixed guide rails  14  is set appropriately in accordance with the mode of arrangement (installing position and direction) of the processing chambers  3 . The said spacing may be taken over the full width of the clean room.  
         [0059]    Next, a description will be given below in detail about the structure of the vertical moving means  13 .  
         [0060]    As shown in FIGS.  3  to  6 , the vertical moving means  13  is constituted by an articulated arm having five arms  16 ˜ 20 . As noted above, the base end portion of the first start-end arm  16  is connected pivotably to the travel body  15  so that the vertical moving means  13  can travel in a horizontal plane together with the travel body  15 .  
         [0061]    As best shown in FIG. 6, the five arms  16 ˜ 20  are arranged successively in an alternate manner such that, with respect to one virtual vertical plane A, the first start-end arm  16  is located on the left-hand side, the second arm  17  on the right-hand side, and the third arm  18  on the left-hand side, the arms being overlapped and connected alternately at their end portions. By so doing, the center of gravity of the articulated arm is not dislocated and the weight balance of the entire arm becomes stable, so that a gravitational deflection is diminished also upon extension of the articulated arm (upon lowering of the vertical moving means  13 ). Further, as is apparent from a comparison between FIG. 7( 2 ) which relates to a conventional example and FIG. 4, a folded state of the vertical moving means  13  is compact, whereby the disturbance of an air flow with travel of the vertical moving means can be kept to a minimum.  
         [0062]    The vertical moving means  13  has a motor  21  as a single drive source and a structure having a certain pivoting ratio (1:2:1:2:1) among the arms The whole of the articulated arm (vertical moving means  13 ) extends and contracts with operation of the motor  21  and consequent pivotal movements of the arms  16 ˜ 20 . As a result, the work holding means  11  fixed to the fifth terminal-end arm  20  rises and falls on a straight line. This rising and falling motions are performed automatically by control of the motor  21 . Under the structure having a certain pivoting ratio among the arms, which is based on 1:2:1, the number of arms which constitute the articulated arm, is not limited to five, but may be three or seven.  
         [0063]    As shown in FIGS. 4 and 6, the motor  21  is installed on the first arm  16  side unlike the prior art wherein it is installed on the travel body  15  side. An upper empty space in the interior of the first arm  16  is utilized to receive the motor  21  therein. According to this construction, the sealing of dust generated from the motor  21  as a single drive source and the sealing of dust generated from the structure having a certain pivoting ratio among the arms may all be done on the arm side, thus affording a structure easy to seal. The pivoting of the first start-end arm  16  for the horizontal moving mans  12 , as well as the pivoting of the succeeding second to fifth arms  17 ˜ 20  through the structure having a certain pivoting ratio among the arms, are all conducted by operation of the motor  21 . As the structure having a certain pivoting ratio among the arms there may be used a known transmission mechanism such as one using plural pulleys and plural belts having a certain diametrical ratio, one utilizing a linkage of only plural gears, or one utilizing a linkage of only plural wires.  
         [0064]    Joint shafts  22 ˜ 25  (see FIG. 6) which connect adjacent arms pivotably, out of the five constituent arms  16 ˜ 20  of the articulated arm, are formed to have a hollow structure though not shown in detail, and the internal spaces of the arms  16 ˜ 20  are mutually communicated and are supplied with a negative pressure. A work rotation drive unit  27  provided in the work holding means  11  is also formed to have a hollow structure and is brought into communication with the internal spaces of the arms  16 ˜ 20  (see a communication path indicated with chain lines in FIG. 6). Dust generated from the said drive unit is sucked in with a negative pressure and is conducted to the arm side.  
         [0065]    The dust generated in the internal spaces of the arms  16 ˜ 20  and the work rotation drive unit  27  is sucked into the internal space of the associated fixed guide rail  14  through the internal space of the travel body  15  and is discharged to the exterior of the clean room from a discharge port formed on one end side of the guide rail. Alternatively, there may be adopted a construction wherein the dust is discharged into the clean room through one or plural filters installed halfway of the fixed guide rail  14 . According to this construction, the structure for the discharge of dust generated in the internal spaces of the arms  16 ˜ 20  and the work rotation drive unit  27  is simplified and it becomes easier to discharge the dust.  
         [0066]    As noted earlier, the work holding means  11  is fixed to the fifth terminal-end arm  20 , and when a work holding portion  26  holds the top of the hermetically sealed container  6 , the work holding means  11  is raised by the vertical moving means  13  and is conveyed to a predetermined processing chamber  3  by the horizontal moving means  12 . Then, when the work holding means  11  arrives at the predetermined processing chamber  3 , it is moved down by the vertical moving means  13  and the work holding portion  26  releases the container  6 , which in turn is placed on a table of the associated interface device  4 . At this time, if there occurs the necessity of correcting the direction in which the container  6  is placed, the work rotation drive unit  27  in the work holding means  11  operates and causes the container  6  to rotate a required quantity in a horizontal plane, whereby the direction in which the container  6  is placed can be corrected.  
         [0067]    Since this first embodiment is constructed as above, there can be obtained the following effects.  
         [0068]    The vertical moving means  13  provided in the horizontal moving means  12  which is a constituent of the work conveying system  10  installed in the clean room, is constituted by an articulated arm, the plural arms  16 ˜ 20  as constituents of the articulated arm are overlapped and connected at their end portions successively in an alternate manner, and the articulated arm is extended and contracted with pivotal movements of the arms  16 ˜ 20 , so that the center of gravity of the articulated arm is not dislocated, the weight balance of the entire arm becomes stable, and there occurs little gravitational deflection even upon extension of the articulated arm (upon lowering of the vertical moving means  13 ). Consequently, it becomes possible for the work holding means  11  to delivery the works to each processing apparatus without any positional deviation, and the extension and contraction of the articulated arm can be done smoothly. Thus, when conveying the works horizontally, the disturbance of an air flow can be kept to a minimum by folding the vertical moving means  13  compactly. Besides, since there occurs no torque based on the weight of the entire arm and the weight of the works, it is possible to effect a stable conveyance of the works horizontally.  
         [0069]    Moreover, the vertical moving means  13  is constituted by an articulated arm having three or more arms  16 ˜ 20  and has the motor  21  as a single drive source and the structure having a certain pivoting ratio among the arms, and the articulated arm is extended and contracted by operation of the motor  21  and consequent pivotal movements of the arms  16 ˜ 20 . Thus, in the vertical moving means  13 , the arms  16 ˜ 20  are interlocked with one another by the single motor  21  and the combined use of three or more motors  16 ˜ 20 , affording a smooth motion free of impact.  
         [0070]    Further, in the vertical moving means  13 , since the pivotal movement of the first start-end arm  16  relative to the horizontal moving means  12  is conducted by operation of the motor  21  as a single drive source provided on the first arm  16  side, the sealing of dust generated from the motor  21  and the sealing of dust generated from the structure having a certain pivoting ratio among the arms may all be done on the arm side and hence it becomes easy to effect the sealing. Besides, since an empty space in the interior of the first arm  16  can be utilized to receive the motor  21  therein, there is obtained a work conveying system  10  of a compact structure.  
         [0071]    Further, since the joint shafts  22 ˜ 25  of the articulated arm have a hollow structure and the internal spaces of the arms  16 ˜ 20  are communicated with one another and are supplied with a negative pressure, the structure for the discharge of dust generated in the internal spaces of the arms  16 ˜ 20  is simplified and it becomes easier to discharge the dust. Consequently, the amount of dust leaking into the clean room is greatly decreased and it becomes easy to maintain the cleanness of the clean room.  
         [0072]    Further, since the work holding means  11  is provided with the work rotation drive unit  27  in addition to the work holding portion  26 , it is not only possible to effect a desired conveyance of the hermetically sealed container  6  which contains the works in a three-dimensional space but also possible to make a rotational direction/posture control for the container in a horizontal plane. Thus, it is possible to establish a rotational direction accurately at the time of loading the works and hence possible to fully satisfy even a high-degree of requirement for the work conveying system.  
         [0073]    Further, since the work rotation drive unit  27  is formed to have a hollow structure and is put in communication with the internal spaces of the arms  16 ˜ 20  and the dust generated from the drive unit is sucked in by virtue of a negative pressure, the structure for discharging the dust generated in the internal space of the work rotation drive unit  27  is simplified, the discharge of the dust becomes easier, the amount of dust leaking into the clean room is greatly decreased, and it becomes still easier to maintain the cleanness of the clean room.  
         [0074]    Further, since plural works which are wafers or reticles are received within the hermetically sealed container  6  and are held by the work holding means  11 , the works are conveyed in a hermetically sealed state within the clean room and therefore it is also possible to easily attain the retention of a high-degree of cleanness required for the works.  
         [0075]    According to the modification of the first embodiment, since the horizontal moving means  12  is made movable in the upper ceiling space within the clean room and in an arbitrary horizontal plane, the work holding means  11  is also made movable following the horizontal moving means  12  in the upper ceiling space within the clean room and in an arbitrary horizontal plane. As a result, the installing position and direction of such apparatuses as processing chambers  3  installed within the clean room are not restricted and it is possible to select an optimal arrangement. Also in case of newly adding an apparatus such as a processing chamber  3  or in case of changing the arrangement of such apparatuses as processing chambers  3 , it is possible to freely select suitable arrangement and installing direction and hence possible to reduce the cost for such a change in arrangement of apparatuses or an increase of an apparatus. Additionally, the work holding means  11  can be moved linearly from a certain position to an opposite-side position while spanning the central passage, whereby the work processing efficiency within the clean room is improved.  
         [0076]    The following description is now provided about an embodiment (second embodiment) of the invention defined in the foregoing tenth aspect, which is illustrated in FIGS.  7  and  8 .  
         [0077]    [0077]FIG. 7 is a front view showing a raised state of a vertical moving means provided in a work conveying system according to this second embodiment, FIG. 7 corresponding to FIG. 3, and FIG. 8 is a plan view of a work which is held by a work holding means provided in the work conveying system. Portions corresponding to the first embodiment are identified by the same reference numerals.  
         [0078]    In the work conveying system  10  of this second embodiment, a work holding portion  26  of a work holding means  11  holds directly a work  30  alone such as wafer or reticle, as shown in FIG. 7. More specifically, plural hands  32  suspended from a lower surface of the work holding portion  26  hold the work  30  at plural peripheral edge positions. In this way the work holding portion  26  holds the work  30  alone directly.  
         [0079]    As shown in FIG. 8, an identification mark  31  for recognizing processing steps which the work  30  alone is to follow, is affixed to each work  30 , and a detecting means  34  for detecting the identification mark  31  is provided on a lower surface of the work holding portion  26  of the work holding means  11 .  
         [0080]    This second embodiment is different in the above points from the previous first embodiment, but is not different in other points from the first embodiment, so a detailed description thereof will be omitted.  
         [0081]    In this second embodiment constructed as above, when the work holding portion  26  of the work holding means  11  holds a work  30  alone, the identification mark detecting means  34  detects the identification mark  31  affixed to the work  30  alone and transmits the detected signal to the controller in the work conveying system  10 , which in turn conveys the work  30  alone rapidly to each processing chamber (processing apparatus)  3  in accordance with a predetermined sequence, making it possible to let the work  30  alone undergo predetermined processings, in a three-dimensional space within the clean room. Consequently, the working efficiency of the work conveying system  10  can be improved to a remarkable extent. In addition, there can be attained the same effects as in the first embodiment.  
         [0082]    Next, a description will be given below about an embodiment (third embodiment) of the invention defined in the foregoing eleventh aspect, which is shown in FIG. 9.  
         [0083]    [0083]FIG. 9 is a front view showing a state in which an identification mark detecting device is detecting an identification mark, the detecting device being installed within a clean room to which a work conveying system of this third embodiment is applied, Portions corresponding to the second embodiment are identified by the same reference numerals.  
         [0084]    In the work conveying system  10  of this third embodiment, an identification mark detecting device provided with detecting means  34  for detecting the identification mark  31  affixed to the work  30  alone is installed specially within the clean room. As shown in FIG. 9, the identification mark detecting device  33  is provided at an upper corner thereof with a projecting portion  35  capable of entering between the lower surface of the work holding portion  26  in the work holding means  11  and the work  30 . The detecting means  34  is provided on the lower surface of the projecting portion  35 . The detecting means  34  may be incorporated in the tip of the projecting portion  35 .  
         [0085]    This third embodiment is different in the above points from the previous second embodiment, but is not different in other points from the second embodiment, so a detailed description thereof will be omitted.  
         [0086]    In this third embodiment constructed as above, the identification mark detecting device  33  detects the identification mark  31  affixed to the work  30  alone which has been conveyed up to the installed position of the detecting device and transmits the detected signal to the controller in the work conveying system  10 , which in turn conveys the work  30  alone rapidly to each processing chamber (processing apparatus)  3  in accordance with a predetermined sequence, permitting the work to undergo predetermined processings. In this way it is possible to greatly improve the working efficiency of the work conveying system  10 . In addition, there can be attained the same effects as in the second embodiment.  
         [0087]    The present invention is not limited to the above embodiments, but various modifications may be made within the scope not departing from the gist of the invention.  
         [0088]    The entirety of the teachings of Japanese patent applications Nos. 2001-253910 and 2001-283407, inclusive of their specifications, claims and drawings, are incorporated herein by reference.