Abstract:
A conveyance apparatus includes an extendable and retractable mechanism, which includes a plurality of linked member pairs rotatably coupled across each other horizontally in a predetermined direction in pantograph form, a multiple-layer slider, which includes a carrier slider to hold a work product and fixed at one end of the extendable mechanism and at least one movable slider to move in a predetermined direction keeping a predetermined relative position to the carrier slider, and a drive mechanism configured to cause the linked member pairs to expand by changing a relative angle of the crossing linked member pairs.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     This patent specification is based on and claims priority from Japanese patent application, No. 2006-067710 filed on Mar. 13, 2006 in the Japan Patent Office, the entire contents of which are incorporated by reference herein.  
       BACKGROUND  
       [0002]     1. Field of Invention  
         [0003]     Exemplary aspects of the present invention relate to a conveyance apparatus, and more particularly to a conveyance apparatus having a compact conveyance mechanism.  
         [0004]     2. Description of Related Art  
         [0005]     A variety of information technologies have been developed rapidly in conjunction with the recent trend of digitalization of information data. It has become realized to handle large volumes of information data by such information technologies. When handling large information data, it is especially important to develop higher density storage mediums than the existing storage mediums, for example, CD (compact disk) and DVD (digital versatile disk), etc. to store the large information data.  
         [0006]     A related art optical disk as a high density storage medium has been developed to have a finer pattern with a smaller pitch so as to store the large information data. The information data may be written and played by exposing an ultra-violet light having a wavelength of 400 nm onto the optical disk.  
         [0007]     In a related art manufacturing process of the optical disk, a master disk (stamper) is initially prepared. The optical disk is then manufactured using the master. A related art electron-beam-lithography apparatus is widely used in the manufacturing process of the master disk under a vacuum condition of 10 −4  PA. The electron-beam-lithography apparatus irradiates an electron beam onto a surface of a work product, such as wafer, etc. so as to form the fine pattern.  
         [0008]     The related art electron-beam-lithography apparatus generally employs so called three-chambers-and-one-transfer configuration which includes a vacuum process room, a load-lock room and a transfer room. The transfer room is connected to the vacuum process room and the load-lock room. In the vacuum process room, the fine pattern is drawn on the work product under a predetermined vacuum condition. The work product is conveyed from outside where it is under atmospheric pressure. The work product is held in the load-lock room. The work product is then conveyed to the vacuum process room by a conveying arm provided in the transfer room.  
         [0009]     If the work product having a larger size is employed to improve manufacturing efficiency, a large transfer room is necessary to ensure enough stroke of the conveying arm. As a result, there is a penalty because of the large size of the electron-beam-lithography apparatus.  
         [0010]     Another related art electron-beam-lithography apparatus employs so called two-chambers-and-one-transfer configuration where a conveyance mechanism is provided in a load-lock room and a transfer room is not arranged. However, there is a penalty because of the large size of the electron-beam-lithography apparatus similarly.  
         [0011]     Another related art background electron-beam-lithography apparatus employs a telescope-structure conveyance mechanism which includes a plurality of sliders to ensure the conveyance stroke of the conveyance mechanism. However, it is necessary to employ pulleys and belts to connect the sliders. Therefore, a complicated drive mechanism is necessary to control movements of the sliders to have a predetermined mutual relation ship.  
       SUMMARY  
       [0012]     This specification describes a conveyance apparatus including an extendable mechanism, which includes a plurality of linked member pairs rotatably coupled across each other horizontally in a predetermined direction in pantograph form. A multiple-layer slider includes a carrier slider to hold a work product and is fixed at one end of the extendable mechanism. At least one movable slider moves in a predetermined direction keeping a predetermined relative position to the carrier slider. A drive mechanism is configured to cause the linked member pairs to expand by changing a relative angle of the crossing linked member pairs.  
         [0013]     Further, this specification describes a vacuum process apparatus which employs the conveyance apparatus described above and includes a vacuum process room to draw a fine pattern onto the work product therein and a load-lock room connected to the vacuum process room through a gate valve. The conveyance apparatus is provided in the load-lock room and carries the work product conveyed from outside of the load-lock room and to the vacuum process room. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]     A more complete appreciation of the disclosure and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:  
         [0015]      FIG. 1  illustrates a vacuum process apparatus according to a first example embodiment of the present disclosure;  
         [0016]      FIG. 2  illustrates a side view of a conveyance mechanism;  
         [0017]      FIG. 3  illustrates a plane view of the conveyance mechanism;  
         [0018]      FIG. 4A  illustrates a plane view of a lazy-tongs arm when the lazy-tongs arm is expanded;  
         [0019]      FIG. 4B  illustrates a cross-sectional view of the lazy-tongs arm of  FIG. 4A ;  
         [0020]      FIG. 5  illustrates the second vacuum chamber when the gate valve is at a closed position;  
         [0021]      FIGS. 6A and 6B  are illustrations to explain a stroke of the lazy-tongs arm;  
         [0022]      FIGS. 7A and 7B  are illustrations to explain operation of the vacuum process apparatus;  
         [0023]      FIG. 8  illustrates a cross-sectional view of another conveyance mechanism;  
         [0024]      FIG. 9  illustrates an inner view of the second vacuum chamber observing from a plus side of X-axis;  
         [0025]      FIG. 10  is an illustration to explain operation of the loader;  
         [0026]      FIG. 11  illustrates another example of arm-drive unit;  
         [0027]      FIGS. 12A and 12B  illustrates a pressuring unit; and  
         [0028]      FIG. 13  illustrates a cable provided in the lazy-tongs arm. 
     
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS  
       [0029]     In describing exemplary embodiments illustrated in the drawings, specific terminology is employed for the sake of clarity. However, the disclosure of this specification is not intended to be limited to the specific terminology so selected and it is to be understood that each specific element includes all technical equivalents that operate in a similar manner. Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views, particularly to  FIG. 3 , a conveyance apparatus according to an example embodiment of the present invention is described.  
         [0030]      FIG. 1  illustrates a vacuum process apparatus  10  according to a first example embodiment of the present disclosure. The vacuum process apparatus  10  draws a fine pattern on a surface of a work product W, such as a wafer, etc. by exposing an electron beam under a vacuum condition of, for example, 10 −4  PA. A resist film is coated on the surface of the work product W before an exposure process.  
         [0031]     As shown in  FIG. 1 , the vacuum process apparatus  10  includes a rotating table unit  30 , an exposure system  40 , a conveyance mechanism  100 , a first vacuum chamber  20 , a gate valve  22 , a second vacuum chamber  23  and a controller (not shown). The work product is placed on the rotating table unit  30 . The exposure system  40  exposes the electron beam onto the work product W.  
         [0032]     The first vacuum chamber  20  includes the rotating table unit  30  and the exposure system  40 . The second vacuum chamber  23  is connected to the first vacuum chamber  20  through the gate valve  22 . The controller controls a total system of the vacuum process apparatus  10 .  
         [0033]     The rotating table unit  30  is provided on a surface plate  21  arranged on a horizontal surface of the floor. The rotating table unit  30  includes a rotating table  31 , a spindle motor  32  and a slide unit  33 . On the rotating table  31 , the work product W is provided. The spindle motor  32  holds the rotating table  31  horizontally by a shaft  32   a . The shaft  32   a  of the spindle motor  32  is rotated with a predetermined rotating speed. The slide unit  33  holds the spindle motor  32  and drives to move the spindle motor  32  with a predetermined stroke in an X direction in  FIG. 1 .  
         [0034]     The exposure system  40  is arranged above the rotating table unit  30 . The exposure system  40  includes an electron gun  41  and a modulation unit  42 . The electron gun  41  emits the electron beam vertically in a downward direction. The modulation unit  42  collimates the electron beam to the work product W provided on the rotating table  31 .  
         [0035]     For one example, the modulation unit  42  includes a condenser-lens, an aperture, and a plurality of focus lenses. The modulation unit  42  controls to modulate the electron beam emitted from the electron gun  41  and exposes the electron beam by focusing the electron beam onto the surface of the work product W.  
         [0036]     The first vacuum chamber  20  is provided touching tightly on the upper surface of the surface plate  21  with an under-part of first vacuum chamber  20 . The first vacuum chamber  20  includes first and second chamber portions  20   a  and  20   b . The first chamber portion  20   a  has a shape of a rectangular parallelepiped. The second chamber portions  20   b  has a cylindrical shape and is provided above the first chamber portion  20   a.    
         [0037]     The rotating table unit  30  is provided in the first chamber portion  20   a  and the exposure system  40  is provided in the second chamber portion  20   b . At a surface of the first chamber portion  20   a  in a minus side of the X-axis in  FIG. 1 , an opening  20   c  is formed. The opening  20   c  has a rectangular shape and a long side of the rectangular opening is provided in the Y-axis direction. The first vacuum chamber  20  and the surface plate  21  form a room and is defined as a first vacuum room  11 .  
         [0038]     The second vacuum chamber  23  is connected to the first vacuum chamber  20  at the minus side of the X-axis in  FIG. 1 . An opening  23   a  having a similar shape to the opening  20   c  is formed at a surface of the second vacuum chamber  23  in the minus side of the X-axis in  FIG. 1 .  
         [0039]     In an upper surface of the second vacuum chamber  23 , an opening  23   b  is provided. A size of the opening  23   b  is much larger than the work product W. Further, a shutter  23   c  is provided on the upper surface of the second vacuum chamber  23 . The shutter  23   c  opens and closes the opening  23   b  to outside of the second vacuum chamber  23  by sliding on the surface of the second vacuum chamber  23  in a direction of the X-axis. The second vacuum chamber  23  forms a room and is defined as a load-lock room  12 .  
         [0040]     The gate valve  22  includes a frame member and a gate  22   b . The frame member includes an opening  22   a  which passes through completely to the other side of the frame member in the X-axis direction. The gate  22   b  slides on the surface of the second vacuum chamber  23  in a direction of Z-axis to open and close the opening  22   c.    
         [0041]     The gate valve  22  touches tightly with the opening  20   c  of the first vacuum chamber  20  and the opening  23   a  of the second vacuum chamber  23  at both ends of the gate valve  22  in the X-axis direction. As a result, the first vacuum room  11  and the load-lock room  12  are sealed so as to be in a vacuum condition respectively when the gate valve  22  closes the opening  22   a  by sliding the gate  22   b  up to a plus side of Z-axis in  FIG. 1 .  
         [0042]     The first vacuum room  11  and the load-lock room  12  communicate with each other when the gate valve  22  opens the opening  22   a  by sliding the gate  22   b  down to a minus side of Z-axis in  FIG. 1 .  
         [0043]      FIG. 2  illustrates a side view of the conveyance mechanism  100 . The conveyance mechanism  100  includes a multiple-layer slider  50 , a so-called lazy-tongs arm  70  and an arm-drive unit  60  as shown in  FIG. 2 . The multiple-layer slider  50  is provided on an upper surface of a base wall of the second vacuum chamber  23 . The lazy-tongs arm  70  drives the multiple-layer slider  50  in a X-axis direction by expanding and retracting the lazy-tongs arm  70 .  
         [0044]      FIG. 3  illustrates a plane view of the conveyance mechanism  100 . Referring to  FIGS. 2 and 3 , the multiple-layer slider  50  includes a pair of first linear guides  52 A, a first slide table  53 A, a pair of first moving members  51 A, a pair of second linear guides  52 B, a second slide table  53 B and a pair of second moving members  51 B.  
         [0045]     The pair of first linear guides  52 A are provided near edges at a minus side and another side of the Y-axis on the upper surface of the base wall of the second vacuum chamber  23  respectively. The pair of first linear guides  52 A are fixed placing a long side of the first linear guides  52 A in the X-axis direction. The first moving members  51 A are provided slidably to engage with the first linear guides  52 A in the X-axis direction.  
         [0046]     The first slide table  53 A is formed of a plane member. A long side of the first slide table  53 A is placed in the X-axis direction. The first slide table  53 A is held horizontally being fixed with the first moving member  51 A at each corner of a bottom surface in a minus side of the X-axis. Further, the first slide table  53 A is movably provided in the X-axis direction.  
         [0047]     The pair of second linear guides  52 B are provided near edges at the minus side and another side of the Y-axis on the upper surface of the first slide table  53 A respectively. The second linear guides  52 B are fixed placing a long side of the second linear guide  52 B in the X-axis direction. The first moving member  51 B is provided slidably to engage with the second linear guides  52 B in the X-axis direction.  
         [0048]     The second slide table  53 B is formed of a plane member. A long side of the second slide table  53 B is placed in the X-axis direction. The second slide table  53 B is held horizontally by being fixed with the second moving member  51 B at each corner on a bottom surface of a minus side of X-axis. Further, the second slide table  53 B is movably arranged in the X-axis direction. On the second slide table  53 B, three work chucks  54 A,  54 B and  54 C are provided to be located along an outer circumference of the work product W for positioning the work product W.  
         [0049]     The arm-drive unit  60  includes a shaft  62 , a pair of moving members  61 A and  61 B and a motor  63 . The shaft  62  is a rod-like member and a long side of the shaft  62  is placed in the Y-axis direction in the second vacuum chamber  23 . The pair of moving members  61 A and  61 B are provided on the shaft  62 . The motor  63  drives to rotate the shaft  62 .  
         [0050]     The shaft  62  is rotatably held by a pair of bearings  65  fixed on a side wall of the second vacuum chamber  23  at the minus side of the X-axis. On a circumferential surface of the shaft  62 , a male screw  62   a  is formed in a predetermined region in the plus direction of the Y-axis from a center of the shaft  62 . Further, another male screw  62   b , which has an opposite screw direction to the male screw  62   a  with same pitch, is formed in a predetermined region in the minus direction of the Y-axis from a center of the shaft  62 .  
         [0051]     Two lines L 1  and L 2  will be now defined. The dashed line L 1  is passing the center of the long side of the shaft  62  and is parallel with the X-axis direction. The line L 1  is defined as a moving center line. The dashed line L 2  is passing through a center axis of the long side of the shaft  62  that is parallel with the Y-axis direction.  
         [0052]     The moving member  61 A and  61 B includes a moving part  61   a  and a coupling part  61   b . The moving part  61   a  has a rectangular shape and includes a female screw formed at whole inner side of the moving part  61   a  in the Y-axis direction.  
         [0053]     The coupling part  61   b  is an U-shaped member with respect to a Z-X cross-sectional plane and is fixed to the moving part  61   a . Each moving member  61 A and  61 B is engaged with the male screws  62   a  and  62   b  at symmetric positions about the center of the moving center line L 1 .  
         [0054]     The motor  63  is fixed on an outer surface of the side wall of the second vacuum chamber  23  at the minus side of Y-axis. The motor  63  drives to rotate the shaft  62  about the center of the shaft along the Y-axis with a predetermined rotating direction and rpm (revolutions per minute).  
         [0055]     As described, the arm-drive unit  60  includes the shaft  62 , the pair of the moving members  61 A and  61 B and the feed screw mechanism. The feed screw mechanism causes the moving members  61 A and  61 B to move towards opposite direction mutually from each other about the center of the moving center line L 1 . When the shaft  62  is rotated by the motor  63 , the moving members  61 A and  61 B move along the Y-axis direction towards opposite directions from each other (coming closer, separating).  
         [0056]     The lazy-tongs arm  70  is formed of a plurality of linked members engaged each other in pantograph form to expand and retract in an X-axis direction.  
         [0057]      FIG. 4A  illustrates a plane view of the lazy-tongs arm  70  when the lazy-tongs arm  70  is expanded.  FIG. 4B  illustrates a cross-sectional view of the lazy-tongs arm  70  of  FIG. 4A . The lazy-tongs arm  70  includes a plurality of linked bar pairs  71 , center pins  80  and outer pins  81 .  
         [0058]     The linked bar pairs  71  are rotatably coupled across each other by the center pins  80 . Similarly, the linked bar pairs  72  are rotatably coupled across each other by the center pins  80 . The linked bar  72  is rotatably coupled with the linked bar  71  by the outer pin  81  at the end of the linked bar  72 .  
         [0059]     Further, the linked bar  72  is rotatably coupled with an adjacent linked bar  72  by the outer pins  81  at the end of the linked bar  72 . The center pins  80  and the outer pins  81  have cylindrical conformations. Thus, the lazy-tongs arm  70  is formed to be expandable and retractable.  
         [0060]     An end of the linked bar  71  is coupled to the coupling part  61   b  of the moving member  61 A and  61 B by a rotating shaft  82 . A pair of end-linked bars  73  are provided at an end of the lazy-tongs arm  70  and the plus side of the X-axis. One end of the end-linked bar  73  is rotatably coupled by the outer pins  81  with the end-linked bar  72 . Another end of the end-linked bar  73  is rotatably coupled by the center pins  80  with another end-linked bar  73 .  
         [0061]     The center pins  80  are located on the moving center line L 1 . The center pins  80  and outer pins  81  are provided to have an equal distance between neighboring pins respectively. The center pins  80  located in the middle are connected to an upper surface of the first slide table  53 A through a connection member  74 A at a minus side of the X-axis. The center pins  80  located at the most plus side of the X-axis are connected to an upper surface of the second slide table  53 B through a connection member  74 B at the minus side of the X-axis.  
         [0062]     In the first example embodiment of the present disclosure, the center pins  80  and the outer pins  81  are coupled to linked bars  71 ,  72  and  73  via needle-bearings by applying fluorinated lubricant agent so that the lazy-tongs arm  70  can move smoothly.  
         [0063]     The rotating shaft  82  is supported by the coupling part  61   b  of the moving members  61 A and  61 B at upper and bottom ends of the rotating shaft  82 . Further, the rotating shaft  82  may be supported via, for example, a ball bearing.  
         [0064]     The lazy-tongs arm  70  is being expanded and retracted in the X-axis direction by opening and closing the pair of linked bars  71  in accordance with the movements of the moving members  61 A and  61 B of the arm-drive unit  60 .  
         [0065]     Operation of the vacuum process apparatus  10  will now be described. Initially, the lazy-tongs arm  70  of the conveyance mechanism  100  is in a retracted state as shown in  FIG. 3 .  
         [0066]      FIG. 5  illustrates the second vacuum chamber  23  when the gate valve  22  is at a closed position. The first vacuum room  11  is kept at a predetermined vacuum condition, for example, a vacuum condition of 10 −4  PA.  
         [0067]     At this stage, the work product W is not provided on the rotating table  31  and on the second slide table  53 B. Positions of the first and second slide tables  53 A and  53 B are defined as waiting positions. (Refer to  FIG. 2 )  
         [0068]     The work product W is conveyed to a position above the load-lock room  12  by a conveyer (not shown). The opening  23   b  is opened by sliding the shutter  23   c  towards the minus direction of the X-axis under a control of a control apparatus (not shown).  
         [0069]     The work product W is conveyed to a position above the second slide table  53 B of the conveyance mechanism  100  by the conveyer. The opening  23   b  is closed by sliding the shutter  23   c  towards the plus direction of the X-axis. As a result, the load-lock room  12  is sealed so as to be evacuated. When the work product W is mounted, a horizontal position of the work product W is then fixed on the second slide table  53 B by the work chucks  54 A,  54 B and  54 C.  
         [0070]     An inner air of the load-lock room  12  is absorbed by a vacuum pump (not shown) under the control of the controller until, for example, a vacuum condition of 10 −4  PA which is equal vacuum condition to the first vacuum room  11 . After the vacuum condition of the load-lock room  12  becomes equal to the vacuum condition of the first vacuum room  11 , the gate valve  22  is opened.  
         [0071]     The controller controls to drive the motor  63  of the arm-drive unit  60  to rotate the shaft  62 . The moving members  61 A and  61 B are driven to be moved towards the minus and plus Y-axis directions respectively. The lazy-tongs arm  70  starts to expand towards the plus direction of X-axis. The first and second slide tables  53 A and  53 B, which are coupled with the center pins  80  of the lazy-tongs arm  70  through the connection members  74 A and  74 B respectively, start to move towards the plus direction of X-axis by synchronizing in accordance with the expansion of the lazy-tongs arm  70  as shown in  FIG. 4B .  
         [0072]      FIGS. 6A and 6B  are illustrations to explain a stroke of the lazy-tongs arm  70 . In  FIG. 6B , positions of the center pins  80  and the outer pins  81  are shown by black and white circles respectively. Further, positions of the moving members  61 A and  61 B are shown by white squares. Distance between neighboring pins  80  and  81  is defined as L. The stroke of the lazy-tongs arm  70  is defined as S. A displacement of the moving members  61 A and  61 B from a position, which is away from the moving center L 1  by L, is defined as y. To simplify the explanation, the center pin neighboring to the moving members  61 A and  61 B is located apart from the neighboring moving members  61 A and  61 B to have a distance of L.  
         [0073]     The stroke S of the lazy-tongs arm  70  is expressed by a formula (1),  
                   S   =     k   ·         2   ·   L   ·   y     -     y   2                       =     9   ·         2   ·   L   ·   y     -     y   2                         (   1   )             
 
 where y is the displacement of the moving members  61 A and  61 B (0&lt;y&lt;1) and L is the distance between neighboring pins  80  and  81 . In this exemplary embodiment, k is 9. 
 
         [0074]     Namely, the stroke S of the lazy-tongs arm  70  is proportional to a square root of quadratic function of the displacement y of the moving members  61 A and  61 B. A variation of the stroke of the lazy-tongs arm  70  is expressed by a curved line as shown in  FIG. 6B . The formula (1) is matched with the distance of the second slide table  53 B which is coupled to the center pin  80  at the most plus side of the X-axis.  
         [0075]     The controller controls the movement of the arm-drive unit  60  based on the curved line of  FIG. 6B  by monitoring the displacement y of the moving members  61 A and  61 B. The work product W provided on the second slide table  53 B is conveyed to a predetermined position in the first vacuum room  11  by expanding the lazy-tongs arm  70  as shown in  FIGS. 7A and 7B .  
         [0076]     The stroke S′ of the first slide table  53 A from a waiting position of the second slide table  53 B is expressed by a formula (2). The first slide table  53 A is coupled to the center pin  80  provided at a middle of the lazy-tongs arm  70 . 
 
 S′=   5·√{square root over (2· L·y−y   2 )}   (2) 
 
         [0077]     Namely, the first and second slide tables  53 A and  53 B move with a distance SAB between the first and second slide tables  53 A and  53 B expressed by a following formula (3). Further, the first and second slide tables  53 A and  53 B move synchronizing with the lazy-tongs arm  70  with each speed S/dt and S′/dt of the first and second slide tables  53 A and  53 B. Each speed S/dt and S′/dt of the first and second slide tables  53 A and  53 B are obtained by differentiating each stoke S and S′ by time. 
 
 S   AB   =S−S′=   4·√{square root over (2· L·y−y   2 )}   (3) 
 
         [0078]     When the second slide tables  53 B is arrived at a predetermined position in the first vacuum room  11 , the controller sends a stop signal to stop the movement of the arm-drive unit  60  so that the expansion of the lazy-tongs arm  70  is stopped. Then, the work product W placed on the first slide tables  53 B is grasped by transfer chucks (not shown). The transfer chucks are configured to move vertically. The work product W is picked up and is released from the second slide tables  53 B. The work product W is transferred onto the rotating table  31  of the rotating table unit  30 .  
         [0079]     After the work product W is transferred on the rotating table  31 , the controller sends a retracting signal to drive the arm-drive unit  60  to retract the lazy-tongs arm  70 . When the first and second slide tables  53 A and  53 B arrive at the respective waiting positions, the controller sends a stop signal to stop the movement of the arm-drive unit  60 .  
         [0080]     Meanwhile, after the gate valve  22  is closed, the work product W is driven to be rotated with a predetermined rotating speed and is moved to the X-axis direction with a predetermined speed by the rotating table unit  30 . The electron beam emitted from the exposure system  40  is irradiated on the work product W. As a result, a spiral or a concentric fine pattern is drawn on the surface of the work product W.  
         [0081]     After the fine pattern is drawn, the work product W is conveyed back to the load-lock room  12  by the conveyance mechanism  100  in reverse order of the steps described above. Further, the work product W is conveyed to outside by a conveyance system (not shown).  
         [0082]     As described, according to the conveyance mechanism  100  of the first example embodiment of the present disclosure, the conveyance mechanism  100  includes the multiple-layer slider  50  and the lazy-tongs arm  70 . The multiple-layer slider  50  includes the first and second slide tables  53 A and  53 B which move horizontally by sliding. The lazy-tongs arm  70  drives the first and second slide tables  53 A and  53 B to the X-axis direction.  
         [0083]     While the lazy-tongs arm  70  is being expanded and retracted by the driving movement of the arm-drive unit  60 , the first and second slide tables  53 A and  53 B are being driven to move with a predetermined relationship of the distance. Thus, the drive mechanism of the conveyance mechanism  100  can be made simple because it is not necessary to control a plurality of slide tables  53 A and  53 B separately.  
         [0084]     Meanwhile, if pulleys are provided in the first and second slide tables  53 A and  53 B and the first and second slide tables  53 A and  53 B are coupled by a belt, the drive mechanism needs a larger number of parts. As a result, the drive mechanism becomes more complicated. Further, in addition to the increase of the parts which are moving, dust particles may be increased.  
         [0085]     However, according to the conveyance mechanism  100  of the first example embodiment of the present disclosure, it is possible to reduce the dust particles efficiently because of the simple drive mechanism.  
         [0086]     At a position where the stroke S of the lazy-tongs arm  70  is taking a larger number, an increment of the stroke S is becoming smaller. The increment of the stroke S is a slope of the curved line of  FIG. 6B . This means that it is possible to have a higher resolution for the stroke of the lazy-tongs arm  70  in the X-axis direction when the stroke S of the lazy-tongs arm  70  is taking a larger number. Therefore, the work product W can be controlled precisely to have a predetermined position when the second slide table  53 B is conveyed into the first vacuum room  11  by expanding the lazy-tongs arm  70 .  
         [0087]     The distance SAB between the first and second slide tables  53 A and  53 B is being kept to follow the formula (3). Therefore, the connection member  74 A of the first slide table  53 A does not hit the second slide table  53 B even when the lazy-tongs arm  70  is retracted. As a result, a moving range of the moving members  51 A and  51 B does not exceed lengths of the first and second linear guides  52 A and  52 B.  
         [0088]     The vacuum process apparatus  10  according to the first example embodiment of the present disclosure includes the conveyance mechanism  100  as described. It is possible to achieve the simple conveyance system which conveys the work product W between the first vacuum room  11  and the load-lock room  12  and places the work product W accurately at the predetermined position. As a result, a compact and low cost vacuum process apparatus having an excellent performance is realized.  
         [0089]     FIGS.  8  to  10  illustrate a vacuum process apparatus according to a second example embodiment of the present disclosure.  
         [0090]      FIG. 8  illustrates a cross-sectional view of a conveyance mechanism  200  in a XZ-plain. The conveyance mechanism  200  is provided in the load-lock room  12 .  
         [0091]     Comparing to the vacuum process apparatus  10  according to the first example embodiment of the disclosure, the multiple-layer slider  50  of the conveyance mechanism  200  and the lazy-tongs arm  70  are provided top side down. The conveyance mechanism  200  is provided in the second vacuum chamber  23  via a vertical motion drive  90 . A loader  110  is employed to convey the work product W to the load-lock room  12  from the outside.  
         [0092]     The vertical motion drive  90  includes a first unit base  93 , four linear-motion guides  91 , four support poles  92 , a second unit base  94  and a drive shaft  95 . The first unit base  93  has a rectangular shape and is held by the four linear-motion guides  91  horizontally. The drive shaft  95  drives to move the first unit base  93  vertically. The second unit base  94  is held horizontally by the four support poles  92  provided on an upper surface of the first unit base  93 .  
         [0093]     The first linear guides  52 A are fixed at an end in a minus side of Y-axis and other end on a rear side of the second unit base  94 . A longitudinal side of the first linear guides  52 A is provided along the X-axis direction. As a result, the multiple-layer slider  50  of the conveyance mechanism  200  is supported by the vertical motion drive  90 .  
         [0094]     The arm-drive unit  60  is provided above the first unit base  93 . One end of the arm-drive unit  60  is fixed at a minus side of X-axis to an upper surface of the first unit base  93 . As described, the conveyance mechanism  200  supported by the vertical motion drive  90  is driven to move vertically by the vertical movement of the drive shaft  95 .  
         [0095]      FIG. 9  illustrates an inner view of the second vacuum chamber  23  observed from the plus side of X-axis. The loader  110  includes a loader main body  110   a  and a table  100   b . The table  110   b  is coupled to the loader main body  110   a  via parallel links  111 . The parallel links  111  include four link-members.  
         [0096]     The loader main body  110   a  moves in a Y-axis direction and includes an engagement section. The engagement section of the loader main body  110   a  engages with an opening  23   d  which has a rectangular shape and is provided on a sidewall of the second vacuum chamber at a minus side of Y-axis. The loader main body  110   a  is driven to reciprocate between a position shown by a virtual image (waiting position) in  FIG. 9  and another position shown by a solid line image (conveyed position) by a drive mechanism (not shown).  
         [0097]     At the conveyed position, the loader main body  110   a  stops to move by engagement of the engagement section with an opening  23   d . The table  110   b  is positioned right under the second slide table  53 B.  
         [0098]     Operation of the conveyance of the work product W by the conveyance mechanism  200  will be described. Initially, the loader  110  is at the waiting position and the work product W is not provided on the conveyance mechanism  200 .  
         [0099]     The work product W is provided on the table  100   b . The work product W is conveyed to the load-lock room  12  by the movement of the loader  110  towards a plus direction of the X-axis. As shown in  FIG. 10 , the parallel links  111  of the loader main body  100   a  are driven to move to the position shown by the solid image by a drive mechanism (not shown). As a result, the work product W is clamped onto an undersurface the second slide table  53 B by the table  110   b.    
         [0100]     The work product W is fixed by the work chucks provided on the second slide table  53 B. The work chucks may be a L-shape-three-claw chuck  54 A to  54 C, or a rotary-three-claw chuck. In this example embodiment, the L-shape-three-claw chuck is employed. The L-shape-three-claw chuck fixes the work product W by moving in a radial direction as shown in  FIG. 10 . The rotary-three-claw chuck fixes the work product W by rotating a longitudinal part of a L-shape member. The work product W may be fixed by vacuum adsorption or electrostatic adsorption.  
         [0101]     The parallel links  111  of the loader  110  are driven to move down to positions shown by the chained line in  FIG. 10 . The work product W is conveyed to a position above the rotating table  31  in the first vacuum room  11  by the conveyance mechanism  200 .  
         [0102]     The work product W is moved down to a closer position to the rotating table  31  by downward movement of the conveyance mechanism  200  by the vertical motion drive  90 . The work product W is released from the work chucks  54 A to  54 C and is placed onto the rotating table  31 . Then, a fine pattern is drawn on the work product W. After drawing the fine pattern, the work product W is conveyed back to the outside in reverse order of the steps described above.  
         [0103]     As described, according to the vacuum process apparatus according to the second example embodiment of the present disclosure, the conveyance mechanism  200  is moved downward by the vertical motion drive  90 . The work product W is placed onto the rotating table  31  of the rotating table unit  30  without using the transfer chucks which are movable vertically.  
         [0104]     Therefore, the transfer mechanism, which transfers the work product W from the conveyance mechanism  200  to the rotating table  31 , is not necessary in the first vacuum room  11 . As a result, it is possible to form the vacuum process apparatus more compact. Further, the vacuum room can be kept at a low vacuum level because of achieving a low dust level.  
         [0105]     In the vacuum process apparatus according to the second example embodiment of the present disclosure, the arm-drive unit  60  is provided on the first unit base  93  as shown in  FIG. 8 . However, when the motor  93  is arranged outside of the load-lock room, the driving force of the motor  63  may be transferred to the shaft  62  via a pair of gears  66  and an universal joint  67  as shown in  FIG. 11 . Employing this configuration, the motor  63  can drive the shaft  62  so that the work product W can be efficiently conveyed in the horizontal and vertical directions even when the shaft  62  is jogging.  
         [0106]     In each conveyance mechanism  100  and  200  according to the first and second example embodiments of the present disclosure, the lazy-tongs arm  70  is formed of a plurality of linked bars (cross links)  72  across each other and are rotatably connected by the center pins  80 . A number of the cross links may not be three and may be equal to and more than four, or may be equal to and less than two.  
         [0107]     When the number of the cross links of the lazy-tongs arm  70  is plural, an allowance may become large in a x-axis direction when the lazy-tongs arm  70  is retracted. If the allowance is larger than a predetermined amount, a waiting position of  53 A and  53 B may be shifted. As a result, a positioning accuracy is decreased.  
         [0108]     For one example, the carrying mechanisms  100  and  200  include a pressuring unit  120  provided in a middle of the shaft  62  to give a force to the lazy-tongs arm  70 . The pressuring unit  120  includes fixtures  120   a  and  120   b . The lazy-tongs arm  70  is supported by the fixtures  120   a  and  120   b  and may slide in the x-axis direction as shown in  FIGS. 12A and 12B . The fixtures  120   a  and  120   b  are supported by a support member (not shown). Further, the fixture  120   b  is pushed by an elastic member, such as a spring, in the plus direction of the X-axis.  
         [0109]     When the lazy-tongs arm  70  is retracted, the center pin  80  which connects the link bars  71  is pushed by the fixture  120   b  of the pressuring unit  120  towards the plus direction of the X-axis. With this configuration, the slide table  53 A and  53 B are positioned at predetermined waiting positions respectively when the lazy-tongs arm  70  is retracted. As a result, the positioning accuracy can be enhanced.  
         [0110]     In the conveyance mechanism  100  and  200  according to the example embodiments of the present disclosure, when sensor and drive mechanism are provided on the first and second slide tables  53 A and  53 B, a cable  83  can be provided through a hollow part of the outer pin  81  as a guide. Similarly, it is possible to provide hose pipes which supply, for example, driving air and cooling water.  
         [0111]     In the conveyance mechanism  100  and  200  according to the example embodiments of the present disclosure, the first slide table  53 A is connected to the center pin  80  located in the middle of the lazy-tongs arm  70 . However, the first slide table  53 A may be connected to other center pin  80  to match the stroke of the lazy-tongs arm  70 .  
         [0112]     In the conveyance mechanism  100  and  200  according to the example embodiments of the present disclosure, the multiple slider  50  includes two slide tables  53 A and  53 B. However, the multiple-layer slider may include three or more sliders.  
         [0113]     In the conveyance mechanism  100  and  200  according to the example embodiments of the present disclosure, the arm-drive unit  60  includes the shaft  62  and the moving members  61 A and  61 B. However, the arm-drive unit  60  may employ a rack-and-opinion.  
         [0114]     In the conveyance mechanism  100  and  200  according to the example embodiments of the present disclosure, the work product W is conveyed between two rooms under a predetermined vacuum condition. However, the work product W may be conveyed between two rooms under a condition of an inactive gas.  
         [0115]     Numerous additional modifications and variations are possible in light of the above teachings. It is therefore to be understood that within the scope of this patent specification the invention may be practiced otherwise than as specifically described herein.