Abstract:
An apparatus suitable for producing semiconductors. The apparatus includes a processing chamber, a first preparatory chamber, and a second preparatory chamber. Workpieces are transferred to the processing chamber for processing in a vacuum. The first and second preparatory chambers are used for transferring the workpiece between the processing chamber and an exterior exposed to atmospheric pressure without exposing the processing chamber to the atmospheric pressure. The first and second preparatory chambers are aligned vertically, which reduces the floor space occupied by the apparatus.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to appratuses that are suitable for processing semiconductor devices. More particularly, the present invention relates to an apparatus having a semiconductor processing chamber, which is used to process workpieces, and a preparatory chamber, which is used for transferring workpieces without drawing atmospheric air into the processing chamber. 
     There is a type of semiconductor producing apparatus provided with a processing chamber for processing workpieces in a vacuum environment. Workpieces must be transferred in the vacuum environment. There is a need to shorten the time required for transferring workpieces in both vacuum and atmospheric environments. There is also a need to reduce space occupied by the apparatus. The transferring time is the time from when the transferring of one workpiece is started to when the transferring of the next workpiece is started. 
     FIG. 1 is a schematic plan view showing a prior art semiconductor producing apparatus  61 . The apparatus  61  is provided with a processing chamber  62 , a vacuum chamber  63 , and two preparatory chambers  64 ,  65 . The processing chamber  62  is under vacuum and is used to process wafers W in a vacuum environment. The vacuum chamber  63 , which is also under a vacuum, accommodates a first robot  66  to transfer the wafers W. 
     Each preparatory chamber  64 ,  65  has a port. A carrier  67  is arranged in correspondence with the port of the preparatory chamber  64 , while a carrier  68  is arranged in correspondence with the port of the preparatory chamber  65 . A second robot  69  is arranged between the preparatory chambers  64 ,  65  and the carriers  67 ,  68 . The second robot  69  transfers unprocessed and processed wafers W between the carriers  67 ,  68  and the associated preparatory chambers  64 ,  65  in an atmospheric environment. 
     The first robot  66  has two hands  66   a ,  66   b . The hands  66   a ,  66   b  exchange unprocessed wafers W with processed wafers W. More specifically, one of the hands  66   a  ( 66   b ) exchanges unprocessed wafers W with processed wafers W in one of the preparatory chambers  64 ,  65 . The other hand  66   a  ( 66   b ) exchanges unprocessed wafers W with processed wafers W in the processing chamber  62 . Two wafers W are held by each hand  66   a ,  66   b  when the robot  66  transfers the wafers W between the preparatory chambers  64 ,  65  and the vacuum chamber  63  and between the vacuum chamber  63  and the processing chamber  62 . Since two wafers W are held by each hand  66   a ,  66   b , the transfer of the wafers W is more efficient in comparison to when only one wafer W is held by each hand  66   a ,  66   b . Thus, the number of transferred wafers W per unit time is increased. Consequently, the length of time required for the producing apparatus  61  to transfer wafers W is shortened. 
     If the semiconductor producing apparatus  61  is used in a clean room, the wafers W exposed to atmospheric air must be transferred in clean environments. Thus, devices that are used to transfer wafers W in atmospheric air, such as the carriers  67 ,  68  and the preparatory chambers  64 ,  65 , are installed at locations that are relatively cleaner than other locations. Devices that transfer wafers W in a vacuum state, such as the processing chamber  62  and the vacuum chamber  63 , are installed at less clean locations. 
     In the prior art apparatus  61 , the preparatory chambers  64 ,  65 , which require a clean environment, are arranged next to each other. Therefore, the part of the apparatus  61  that is exposed to the atmosphere occupies a large amount of floor area, or horizontal area. The devices that transfer wafers W in the atmospheric air (located at the front section of the apparatus  61 ) occupy a large portion of the apparatus  61 . Thus, the floor space requiring a cleaner environment is relatively large, which increases costs. 
     Accordingly, it is an objective of the present invention to provide an apparatus for producing semiconductor devices that occupies less floor area without decreasing throughput. 
     SUMMARY OF THE INVENTION 
     To achieve the above objective, the present invention provides an apparatus for handling wafer-like workpieces, wherein the apparatus comprises: a processing chamber to which a workpiece is transferred and for performing a predetermined process on the workpiece; and a first preparatory chamber and a second preparatory chamber for transferring the workpiece between the processing chamber and an exterior, wherein the first and second preparatory chambers are aligned vertically. 
     The present invention further provides an apparatus for handling semiconductors wafers, wherein the apparatus comprises: a processing chamber to which a wafer is transferred for performing a predetermined process on the wafer in a vacuum; a vacuum chamber, which is maintained at a controlled level of vacuum, laterally connected to the processing chamber; a transfer chamber, which is maintained at a controlled level of vacuum, laterally connected to the vacuum chamber, the transfer chamber having an upper side and a lower side; a first preparatory chamber connected to the upper side of the transfer chamber; a second preparatory chamber aligned vertically with the first preparatory chamber and connected to the lower side of the transfer chamber, wherein the first and second preparatory chambers are constructed to permit transfer of a wafer between the processing chamber and an exterior exposed to atmospheric pressure without exposing the transfer chamber to the atmospheric pressure. 
     Other aspects and advantages of the present invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The features of the present invention that are believed to be novel are set forth with particularity in the appended claims. The invention, together with objects and advantages thereof, may best be understood by reference to the following description of the presently preferred embodiments together with the accompanying drawings in which: 
     FIG. 1 is a schematic plan view showing a prior art semiconductor producing apparatus; 
     FIG. 2 is a schematic plan view showing a preferred embodiment of a semiconductor producing apparatus according to the present invention; 
     FIG. 3 is a diagrammatic cross-sectional view showing a preparatory chamber of the apparatus of FIG. 2; 
     FIG. 4 is a diagrammatic cross-sectional view taken along line  4 — 4  in FIG. 3; 
     FIG. 5 is a block diagram showing the electric structure of a controller; 
     FIG. 6 is a diagrammatic cross-sectional view showing the preparatory chamber during the transfer of wafers W; 
     FIG. 7 is a diagrammatic cross-sectional view showing the preparatory chamber during the transfer of wafers W; 
     FIG. 8 is a diagrammatic cross-sectional side view showing the preparatory chamber during the transfer of wafers W; and 
     FIG. 9 is a schematic plan view showing a further embodiment of a semiconductor producing apparatus according to the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A first embodiment according to the present invention will now be described with reference to FIGS. 2 to  8 . 
     As shown in FIG. 2, a semiconductor producing apparatus  1  is provided with a processing chamber  2 , a vacuum (handling) chamber  3 , and a transfer chamber  21 . An outside air of the apparatus  1  is preferably atmospheric enviroment, however, the outside air may be another atmosphere. The processing chamber  2 , the vacuum chamber  3  and the transfer chamber  21  are prefarably maintained in a vacuum, or another atmosphere that is different from the atmospheric environment. A preparatory chamber  32  is arranged above the transfer chamber  21 , while another preparatory chamber  43  is arranged below the transfer chamber  21 . Each preparatory chamber  32 ,  43  communicates with the transfer chamber  21 . Wafers W are transferred to the processing chamber  2  for processing. The preparatory chambers  32 ,  43  are used to transfer wafers W without exposing the processing chamber  2  to the atmosphere. 
     The vacuum chamber  3  is hexagonal and connected to the processing chamber  2  on one side and to the transfer chamber  21  on the opposite side. As shown by the dotted lines in FIG. 2, further processing chambers  2  may be connected to each of the remaining four sides of the vacuum chamber  3 . Thus, a maximum number of five processing chambers  2  may be employed. In such case, five wafers may be processed simultaneously. 
     A first conveyor, or first robot  5 , is installed in the vacuum chamber  3 . The first robot  5  transfers wafers W in a vacuum environment between the processing chamber  2  and the transfer chamber  21 . The robot  5  has an arm  7 , and two hands  6   a ,  6   b , which are located on opposite ends of the arm  7 , respectively. Each hand  6   a ,  6   b  is rotatable in a horizontal plane about a vertical axis of the robot  5  and is radially movable with respect to the vertical axis of the arm  7 . 
     The robot  5  transfers wafers W between the processing chamber  2  and the transfer chamber  21 . More specifically, the robot  5  transfers processed and unprocessed wafers W by lifting a processed wafer W in the processing chamber  2  with one of the hands  6   a  ( 6   b ) and exchanging the processed wafer W with an unprocessed wafer W, which is held in the other hand  6   b  ( 6   a ). This structure enables a processed wafer W and an unprocessed wafer W to be transferred during a single step and thus shortens the actual time required to transfer a single wafer W. 
     A second conveyor, or an articulated-arm type second robot  8 , is arranged in front of the transfer chamber  21  (toward the bottom of the drawing). The robot  8  has a base  9  and an arm  12 . The arm  12 , which is mounted on the base  9 , includes a first arm portion  10   a , a second arm portion  10   b , and a hand  11 . The second arm portion  10   b  is coupled to the distal end of the first arm portion  10   a , while the hand  11  is connected to the distal end of the second arm portion  10   b . The first arm portion  10   a  is rotatable in horizontal plane and is vertically movable along its rotating axis. The second arm portion  10   b  and the hand  11  are rotatable in a horizontal plane about a pivot joint between the arm portions  10   a ,  10   b . Thus, the hand  11  is moved horizontally and vertically in accordance with the movement of the arm portions  10   a ,  10   b.    
     Carriers  13 ,  14  are installed in front of the robot  8  at predetermined positions. Each carrier  13 ,  14  holds predetermined lots of processed and unprocessed wafers W. In each carrier  13 ,  14 , the wafers W are stored in a level position. The unprocessed wafers W in the carriers  13 ,  14  are transferred to the transfer chamber  21  by the arm  12 . The processed wafers W, which have been sent to the preparatory chambers  32 ,  43 , are transferred to the carriers  13 ,  14  by the arm  12 . 
     As shown in FIG. 3, the box-like transfer chamber  21  is connected to the vacuum chamber  3  by a communication passage  15 . Level wafers W are moved horizontally through the communication passage  15  between the vacuum chamber  3  and the transfer chamber  21 , which are maintained in a vacuum. 
     The transfer chamber  21  has a top wall  21   a  through which a transfer passage  22  is formed. The transfer passage  22  is round and has a diameter that is larger than the wafers W to permit the transfer of the wafers W between the transfer chamber  21  and the carriers  13 ,  14 . 
     An upper cover  23  is arranged on the top wall  21   a  of the transfer chamber  21  to selectively open and close the transfer passage  22 . The upper cover  23  is cup-like and has a diameter that is substantially the same as that of the transfer passage  22 . The upper cover  23  is supported by guides (not shown) so that it is vertically movable. An upper solenoid  25  drives the upper cover  23 . The device for driving the upper cover  23  is not limited to the solenoid  25  and may be replaced by other devices such as a fluid cylinder or an electric motor. The upper solenoid  25  selectively moves the upper cover  23  between a closed position, at which the cover  23  closes the transfer passage  22 , and a transfer position (refer to FIG.  6 ), at which the cover  23  opens the transfer passage  22 . 
     An upper stage  24  is accommodated in the transfer chamber  21 . The upper stage  24  is disk-like and has a diameter that is larger than that of the transfer passage  22 . A support  26  extends laterally from the upper stage  24 . The support  26  is connected to the top end of a cylindrical first shaft  27 , which extends through the wall of the transfer chamber  21 . The shaft  27  is connected to an upper fluid cylinder  28 , which lowers or lifts the upper stage  24 . The shaft  27  is arranged at a position that does not interfere with the transferring of the wafers W. The device for driving the shaft  27  is not limited to the fluid cylinder  28  and may be replaced by other devices such as a solenoid or an electric motor. The upper stage  24  illustrated in FIG. 3 is located at a lowermost position, which corresponds to a transfer position. When the upper stage  24  is lifted, the upper surface of the upper stage  24  comes into contact with the lower surface of the top wall  21   a  and closes the transfer passage  22  (refer to FIG.  6 ). In this state, the upper stage  24  is located at a closed position. 
     A pair of upper wafer holders  29  are arranged on the upper surface of the upper stage  24 . As shown in FIG. 4, the upper holders  29  hold each wafer W at a predetermined height from the surface of the upper stage  24 . 
     As shown in FIG. 6, when the upper stage  24  is located at the closed position, the wafer W held on the upper holders  29  is arranged above the top wall  21   a . The hand  11  of the second robot  8  lifts the wafer W at this position. When the upper stage  24  is lowered to the transfer position shown in FIG. 3, the wafer W is held on the upper holders  29  at a position enabling the hand  6   a  (or hand  6   b ) of the first robot  5  to lift the wafer W. 
     An upper vacuum valve  30  and an upper atmospheric valve  31  are connected to the upper cover  23 . The upper preparatory chamber  32  is defined when the upper cover  23  and the upper stage  24  are both located at their closed positions. If the upper vacuum valve  30  is opened in this state, a vacuum pump (not shown) discharges gases out of the sealed upper preparatory chamber  32  until the chamber  32  reaches a predetermined level of vacuum. 
     When the upper stage  24  is lowered to the transfer position, one of the hands  6   a  ( 6   b ) of the first robot  5  lifts an unprocessed wafer W on the holders  29  to transfer the wafer W to the processing chamber  2 . The processed wafer W held by the other hand  6   b  ( 6   a ) is then placed on the upper holders  29  and is lifted by the upper stage  24  to the upper preparatory chamber  32 . 
     If the atmospheric valve  31  is opened with the upper preparatory chamber  32  in a sealed state, the chamber  32  is supplied with nitrogen gas by a supply source (not shown) until the pressure in the chamber  32  becomes equal to the atmospheric pressure. When the upper cover  23  is moved to the transfer position, the hand  11  of the first robot  5  lifts a processed wafer W on the holders  29  to transfer the wafer W to the carriers  13 ,  14 , which are located in atmospheric environments. The hand  11  then transfers an unprocessed wafer W stored in the carriers  13 ,  14  to the upper holders  29 , which are still located at the same position. In this state, the bottom of the transfer passage  22  is closed by the upper stage  24 . Thus, the transfer chamber  21 , the vacuum chamber  3 , and the processing chamber  2  are maintained in a vacuum state. Accordingly, the wafers W are transferred between the carriers  13 ,  14  and the vacuum chamber  3  while the transfer chamber  21  is maintained in a vacuum. 
     As shown in FIG. 3, the upper and lower sections of the transfer chamber  21  are mostly symmetrical and identical to each other. Thus, parts that are identical will not be described. Parts differing from the upper section will now be described. 
     A support  37  extends laterally from a lower stage  35 . The support  37  is connected to the top end of a tubular second shaft  38 . The first shaft  27  extends through the second shaft  38 . The first and second shafts  27 ,  38  are coaxial. The second shaft  38  and the support  37  are arranged at a position that does not interfere with the transferring of the wafers W. However, the arrangement of the second shaft  38  and the first shaft  27  are not limited to the illustrated construction and may be arranged at numerous other positions that do not interfere with the movement of the wafers W. Furthermore, the first and second shafts  27 ,  38  do not necessarily have to be coaxial to each other. The second shaft  38  is inserted into a sleeve  44 . Although the first and second shafts  27 ,  38  are vertically movable, the space between the shafts  27 ,  38  and the space between the shaft  38  and the sleeve  44  are sealed. Thus, the transfer chamber  21  is maintained in a sealed state. 
     As shown in FIG. 4, the lower stage  35  has a pair of L-shaped holders  40  to hold a wafer W. The lower holders  40  hold the wafer W at a position that is separated from the lower surface of the lower stage  35  by a predetermined distance. 
     As shown in FIG. 3, when the lower stage  35  is located at the closed position, the lower holders  40  are arranged below the lower surface of a bottom wall  21   b  of the transfer chamber  21 . The hand  11  of the second robot  8  lifts the wafer W at this position. When the lower stage  35  is lifted to the transfer position shown in FIG. 6, the wafer W is held on the lower holders  29  at a position enabling the hand  6   a  (or hand  6   b ) of the first robot  5  to lift the wafer W. 
     A vacuum valve  45  and an atmospheric valve  46  are connected to the vacuum chamber  3 . If the vacuum valve  45  is opened, the gases in the vacuum chamber  3  are discharged until the chamber  3  reaches a certain level of vacuum. If the atmospheric valve  46  is opened, the pressure in the vacuum chamber  3  becomes equal to the atmospheric pressure. The vacuum level of the vacuum chamber  3  decreases when the wafers W are transferred between the vacuum chamber  3  and the carriers  13 ,  14 . Thus, the vacuum valve  45  is provided to maintain the vacuum pressure in the vacuum chamber  3  equal to that in the processing chamber  2 . 
     When the preparatory chambers  32 ,  43  are depressurized to the same vacuum pressure as the processing chamber  2 , a long period of time is necessary to discharge the gases. This lengthens the period of time required to transfer the wafers W. Thus, each wafer W is transferred into the vacuum chamber  3  as soon as the pressure in the preparatory chambers  32 ,  43  falls to a predetermined value. Each unprocessed wafer W is then transferred into the processing chamber  2  when the pressure in the vacuum chamber  3  becomes equal to the vacuum pressure in the processing chamber  2 . This decreases the time required for discharging gases from the preparatory chambers  32 ,  43  and shortens the wafer transfer time. 
     FIG. 5 illustrates the electric structure of a controller  48 , which is employed to control various actuators. The solenoids  25 ,  36  are connected to the controller  48 . The controller  48  actuates the solenoids  25 ,  36  to shift the associated covers  23 ,  34  between the transfer position and the closed position. 
     The cylinders  28 ,  39  are also connected to the controller  48 . The controller  48  actuates the cylinders  28 ,  39  to shift the associated stages  24 ,  35  between the closed position and the transfer position. The first and second robots  5 ,  8  are also connected to the controller  48 . The controller  48  controls the first robot  5  to transfer wafers W between the transfer chamber  21  and the processing chamber  2 . The controller  48  controls the second robot  8  to transfer wafers W between the carriers  13 ,  14  and the preparatory chambers  32 ,  43 . 
     The valves  30 ,  31 ,  41 ,  42 ,  45 ,  46  are connected to the controller  48 . The controller  48  selectively opens and closes each valve  30 ,  31 ,  41 ,  42 ,  45 ,  46  to adjust the vacuum pressure in the associated chambers  3 ,  21 ,  32 ,  42 . 
     The transferring of the wafers W by the semiconductor producing apparatus will now be described. 
     When the upper preparatory chamber  32  is closed and sealed with a processed wafer W accommodated therein, the lower cover  34  is arranged at its closed position and the lower stage  35  is arranged at its transfer position. 
     In this state, the controller  48  opens the atmospheric valve  31  until the pressure in the upper preparatory chamber  32  becomes equal to the atmospheric pressure. As shown in FIG. 6, the controller  48  then actuates the upper solenoid  25  to move the upper cover  23  to the transfer position. The controller  48  controls the second robot  8  to lift a processed wafer W held on the upper holders  29  with the hand  11  and transfer the wafer W to the carriers  13 ,  14 . 
     The controller  48  then controls the second robot  8  to lift an unprocessed wafer W, stored in the carriers  13 ,  14 , and transfer the wafer W onto the upper holders  29 . Afterward, the controller  48  actuates the upper solenoid  25  to move the upper cover  23  to its closed position. This closes and seals the preparatory chamber  32 . The upper vacuum valve  30  is then opened to discharge gases from the preparatory chamber  32  and depressurize the preparatory chamber  32  to a vacuum pressure. 
     In the meantime, the controller  48  controls the first robot  5  to lift the processed wafer W in the processing chamber  2  with one of the hands  6   a  ( 6   b ) of the first robot  5 . An unprocessed wafer W held by the other hand  6   b  ( 6   a ) is transferred into the processing chamber  2  for subsequent processing. 
     The controller  48  subsequently actuates the upper cylinder  28  and lowers the upper stage  24  to the transfer position. The controller  48  then controls the first robot  5  to lift the unprocessed wafer W held on the upper holders  29  with one of the hands  6   a  ( 6   b ) and transfer the processed wafer W held by the other hand  6   b  ( 6   a ) onto the upper holders  29 . 
     The transfer of the wafers W between the processing chamber  2  and the carriers  13 ,  14  by way of the upper preparatory chamber  32  is performed as described above. The transferring of the wafers W between the processing chamber  2  and the carriers  13 ,  14  by way of the lower preparatory chamber  43  is performed in the same manner. 
     The advantages obtained by the preferred and illustrated embodiments will now be described. 
     The two preparatory chambers  32 ,  43  of the semiconductor producing apparatus  1  are located vertically above and below the transfer chamber  21 . Thus, the area occupied by the preparatory chambers  32 ,  43  is decreased dramatically in comparison to the prior art preparatory chambers  64 ,  65 , which are arranged horizontally. 
     The transfer position of the upper holders  29  (refer to FIG. 7) is the same as the transfer position of the lower holders  40  (refer to FIG.  8 ). Thus, the transfer of wafers W between the holders  29 ,  40  and the hands  6   a ,  6   b  is performed in the same manner regardless of which holder  29 ,  40  is holding the wafer W. This simplifies the movement of the robot  5 . Thus, the robot  5  transfers wafers W at a faster speed in comparison to when different movements are necessary for different holders  29 ,  40 . 
     In the prior art semiconductor producing apparatus  61 , the preparatory chambers  64 ,  65  are arranged along the same horizontal plane. Thus, the transfer route for transferring wafers W to the preparatory chambers  64 ,  65  must be set separately for each chamber  64 ,  65 . However, in the semiconductor producing apparatus  1  according to the present invention, the transfer route of each hand  6   a ,  6   b  for the corresponding holders  29 ,  40  is the same. This reduces the number of robot teaching points. 
     It should be apparent to those skilled in the art that the present invention may be embodied in many other specific forms without departing from the spirit or scope of the invention. Particularly, it should be understood that the invention may be embodied in the following forms. 
     More than one wafer W may be accommodated in each preparatory chamber  32 ,  43 . For example, as shown in FIG. 9, a semiconductor producing apparatus  51  having two preparatory chambers  32 ,  43  (the lower preparatory chamber  43  is not shown) may accommodate two wafers W in each preparatory chamber  32 ,  43 . In this case, the upper cover  52  and the upper stage (not shown) are elliptical. A robot  54 , which is installed in a vacuum chamber  53 , has two arms  7  with each arm  7  having two hands  6   a ,  6   b  to simultaneously transfer two wafers W. The apparatus  51  includes two processing chambers  2  to simultaneously process two wafers W. This structure increases the throughput. 
     In the embodiment of FIGS. 2 to  8 , the shape of the covers  23 ,  34  may be changed arbitrarily as long as the covers  23 ,  34  are capable of sealing the associated preparatory chambers  32 ,  43 . For example, the covers  23 ,  34  may be box-like. Furthermore, as long as wafers W may be transferred between the preparatory chambers  32 ,  43  and the carriers  13 ,  14 , the covers  23 ,  34  need not be moved as one piece but may be moved in segments. 
     The present invention is embodied in a semiconductor producing apparatus that processes semiconductor wafers (semiconductor substrates). However, the present invention may also be embodied in an apparatus that transfers and processes other types of workpieces such as glass substrates used for sapphire substrate liquid crystal displays (LCD) and plasma displays (PDP). In such cases, the same advantages of the preferred embodiments are obtained. 
     Therefore, the present examples and embodiments are to be considered as illustrative and not restrictive and the invention is not to be limited to the details given herein, but may be modified within the scope and equivalence of the appended claims.