Abstract:
A gas filling system includes a work platform installed in a pod storage cabinet and defining an accommodation chamber for holding a photomask pod, a pod detaching mechanism disposed in one side of the work platform and controllable to unlock the locking members of the photomask pod for allowing removal of a cover member of the photomask pod from its support tray, and a displacement mechanism mounted in a second side of the work platform and controllable to separate the support tray and the cover member of the photomask pod for allowing filling of an inert gas into the accommodation chamber.

Description:
[0001]    1. Field of the Invention 
         [0002]    The present invention relates to gas filling facility and more particularly, to a gas filling system for SMIF system storage box, for example, photomask pod, which keeps the storage photomask in an airtight environment for the filling of an inert gas so that the filled inert gas maintains excellent cleanliness of the photomask pod. 
         [0003]    2. Description of the Related Art 
         [0004]    The 21 st  Century is the era of digitalization where high-tech products have been developed and intensively used in our daily life, bringing a great convenience to human beings. These high-tech products use IC chips for operation control. It is necessary to employ new knowledge and techniques to control high-tech products such as computer, new generation TV, digital stereo system, central control of building, advanced car, aircraft, and other clothing, food, housing and transportation related products. IC chips are most important components parts in high-tech products. An IC chip is comprised of high-precision integrated circuits, and made through a high-precision processing operation on a silicon single crystal in a clean room by means of a photomask and high-precision machines. These high-precision machines are very expensive. During fabrication of wafers, the yield rate determines the profitability of the foundry. Therefore, it is quite important to a semiconductor factory manager to bring up the yield rate for their products. 
         [0005]    Further, the novel standardized mechanical interface (SMIF) technology is utilized in a clean room for the fabrication of ICs, which reduces particle contamination by significantly reducing particle fluxes onto wafers. During transportation, storage, and most processing steps, the gaseous media surrounding the wafers is essentially stationary relative to the wafers, and particles from exterior environments cannot enter the wafer environments. The SMIF system of wafer handling reduces wafer particle contamination. 
         [0006]    In order to prevent damage to wafers or photomasks, SMIF system storage boxes are used and filled with an inertia gas to deliver wafers or photomasks, preventing oxidation of wafers or photomasks during delivery. A SMIF system photomask pod has a valve device through which gaseous media is filled into the inside space of the photomask pod.  FIGS. 10 and 11  shows a prior art design. According to this design, the photomask pod A comprises a port A 1 , a valve device B mounted in the port A 1  and adapted to close/open the port A 1 , and a spring member C mounted in the port A 1  around the valve device B and holding the valve device B in the close position. The valve device B has a downwardly extending insertion hole B 1  in communication with the atmosphere, and peripheral air outlets B 2 . When filling an inert gas into the photomask pod A, the nozzle tip D of the gas pipe from the inert gas source (not shown) is inserted into the insertion hole B 1  to lift the valve device B, thereby opening the peripheral air outlets B 2  for letting supplied inert gas to pass through the peripheral air outlets B 2  into the inside of the photomask pod A. After removal of the nozzle tip D from the insertion hole B 1 , the spring member C immediately pulls the valve device B back to its former position to close the peripheral air outlets B 2 . This arrangement has drawbacks. During an inert gas filling operation, the spring member C is moved, thereby causing friction with the peripheral wall of the port A 1  and the valve device B. Friction between the spring member C and the peripheral wall of the port A 1  or the valve device B invites particle contamination, thereby destructing the cleanliness of the inside storage space of the photomask pod A. Further, the installation of this photomask pod is complicated. 
       SUMMARY OF THE INVENTION 
       [0007]    The present invention has been accomplished under the circumstances in view. It is the main object of the present invention to provide an inert gas filling system for photomask pod or the like, which eliminates the drawbacks of the aforesaid prior art photomask pod design. 
         [0008]    According to the present invention, the gas filling system is for filling a photomask pod with a gas. The photomask pod comprises a support tray, a cover member detachably covering the support tray, and locking members for locking the cover member to the support tray. The gas filling system comprises a pod storage cabinet, which has a storage, a work platform, which is installed in the bottom side of the storage of the pod storage cabinet and has an accommodation chamber for accommodating the photomask pod and for filling of a gas in the pod stored therein, a pod detaching mechanism, which is disposed in one side of the work platform inside the v storage cabinet and comprises a power drive and actuating means movable by the power drive to lock/unlock the locking members of the pod, and a displacement mechanism, which is mounted in a second side of the work platform and controllable to move the support tray of the pod relative to the cover member of the pod after unlocking of the locking members of the pod. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  is an elevational view of an inert gas filling system in accordance with the present invention. 
           [0010]      FIG. 2  is an exploded view of the inert gas filling system in accordance with the present invention. 
           [0011]      FIG. 3  is an exploded view of a photomask pod for use with the inert gas filling system according to the present invention. 
           [0012]      FIG. 4  is a schematic drawing showing the inert gas filling system installed in a pod storage cabinet according to the present invention. 
           [0013]      FIG. 5  is a schematic drawing of a part of the present invention, showing the pod detaching mechanism in action. 
           [0014]      FIG. 6  is a schematic sectional view of the present invention, showing a status of the inert gas filling system before the inert gas filling operation. 
           [0015]      FIG. 7  is a schematic sectional view of the present invention, showing an inert gas filling status of the inert gas filling system. 
           [0016]      FIG. 8  is a schematic sectional view of an alternate form of the inert gas filling system according to the present invention. 
           [0017]      FIG. 9  corresponds to  FIG. 8 , showing the cover member of the pod removed from the support tray. 
           [0018]      FIG. 10  is a schematic drawing showing the insert gas filling operation of a photomask pod according to the prior art (I). 
           [0019]      FIG. 1110  is a schematic drawing showing the insert gas filling operation of a photomask pod according to the prior art (II). 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0020]    Referring to  FIGS. 1˜5 , an inert gas filling system  1  in accordance with the present invention is shown comprising a work platform  11 , a pod  12 , a pod detaching mechanism  13  and a displacement mechanism  14 . 
         [0021]    The work platform  11  comprises an accommodation chamber  110 , a first opening  111  at the top side of the accommodation chamber  110 , a second opening  112  at the bottom side of the accommodation chamber  110 , and inert gas filling ports  113  in the accommodation chamber  110 . The accommodation chamber  110  is peripherally sealed with an airtight seal means. 
         [0022]    The pod  12  is provided at one side, namely, the top side of the work platform  11  for accommodating a storage item (for example, photomask, semiconductor wafer, substrate, circuit board, etc.)  2 . According to this embodiment, the pod  12  is a photomask pod for holding a photomask. The pod  12  comprises a support tray  121 , a cover member  122  covering the support tray  121 , and locking members  123  for locking the cover member  122  to the support tray  121 . The support tray  121  is provided with support members  1211  for holding the storage item  2  in position. 
         [0023]    The pod detaching mechanism  13  comprises a power drive  131 , and actuating means, for example, movable blocks  132  symmetrically arranged at two sides and movable by the power drive  13  to unlock the locking members  123  of the pod  12 . The movable blocks  132  each have retaining rods for engaging respective retaining holes of the locking members  123  so that the power drive  131  can drive the movable blocks  132  to unlock the locking members  123 . The power drive  13  can be a motor drive, a gear transmission mechanism, a belt transmission mechanism, a linear slide and track assembly, a pneumatic cylinder, a hydraulic cylinder or their combination. 
         [0024]    The displacement mechanism  14  is provided at an opposite side, namely, the bottom side of the work platform  11 , comprising a plurality of vertical motion rods  141 , a carrier plate  142  fixedly fastened to the top ends of the vertical motion rods  141 , and transmission means (not shown) controlled to move the vertical motion rods  141  and the carrier plate  142  in and out of the accommodation chamber  110  of the work platform  11 . The transmission means can be a motor drive, gear transmission mechanism, belt transmission mechanism, pneumatic cylinder, hydraulic cylinder, etc., that can move the vertical motion rods  141  and the carrier plate  142  in and out of the accommodation chamber  110  of the work platform  11 . 
         [0025]    Referring to  FIGS. 2˜5 , the inert gas filling system  1  is installed in the bottom side of one storage  31  of a pod storage cabinet  3 , which has an openable access door  32 . When a user is going to fill an inert gas in the pod  12 , open the access door  32  of the storage  31 , and then put the pod  12  in the storage  31  and placed on the carrier plate  142  of the displacement mechanism  14 , and then close the access door  32 , and then operate the power drive  131  of the pod detaching mechanism  13  to move the movable blocks  132 , thereby unlocking the locking members  123 . 
         [0026]    Referring to  FIGS. 6 and 7  and  FIGS. 2 and 4  again, after separating of the cover member  122  from the support tray  121 , the cover member  122  of the pod  12  is kept secured to the movable blocks  132  of the pod detaching mechanism  13  in such a position that the cover member  122  seals the first opening  111  of the accommodation chamber  110  of the platform  11 , and then the displacement mechanism  14  is operated to lower the carrier plate  142  and the support tray  121  into the accommodation chamber  110  of the work platform  11 , holding the carrier plate  142  in such a position that the carrier plate  142  seals the second opening  112  of the accommodation chamber  110  of the work platform  11 . Thus, the accommodation chamber  110  is kept in an airtight status. At this time, an inert gas supply source (not shown) is connected to one of the inert gas filling ports  113  to fill an inert gas into the accommodation chamber  110  of the platform  11 . The inert gas can be nitrogen gas, helium gas or neon gas. After filling of the inert gas, the vertical motion rods  141  of the displacement mechanism  14  are moved to lift the carrier plate  142  and the support tray  121  to the cover member  122 , and then the power drive  131  of the pod detaching mechanism  13  is operated to move the movable blocks  132 , forcing the locking members  123  from the unlocking position to the locking position to lock the cover member  122  to the support tray  121 . Thereafter, open the access door  32 , and then remove the pod  12  from the pod storage cabinet  3 . 
         [0027]    The aforesaid pod detaching mechanism  13  is adapted to lock/unlock the support tray  121  and the cover member  122 . The power drive  131  of the pod detaching mechanism  13  can be a motor drive, screw transmission mechanism or any of a variety of equivalent means capable of moving the movable blocks  132  to shift the locking members  123  between the locking position and the unlocking position. Other equivalent means may be used to substitute for the movable blocks  132 . 
         [0028]      FIGS. 8 and 9  show an alternate form of the displacement mechanism  14 . According to this embodiment, the displacement mechanism  14  is provided above the pod  12 , comprising a plurality of vertical motion rods  141  and a plurality of vacuum mounts  143  respectively fixedly fastened to the bottom ends of the vertical motion rods  141 . 
         [0029]    When the user is going to fill an inert gas into the pod  12 , the pod detaching mechanism  13  is operated to detach the support tray  121  and the cover member  122 , and then the displacement mechanism  14  is operated to lower the motion rods  141  and to force the vacuum mounts  143  into positive engagement with the cover member  122  of the pod  12  by means of vacuum suction, and then the displacement mechanism  14  is operated to lift the motion rods  141  and the attached cover member  122 , separating the cover member  122  from the support tray  121  and forcing the cover member  122  to seal the first opening  111  of the accommodation chamber  110  of the work platform  11 . Thus, the accommodation chamber  110  of the work platform  11  is kept in an airtight status. The user can than fill an inert gas into the accommodation chamber  110  through the inert gas filling ports  113 . After filling of a predetermined amount of the inert gas in the accommodation chamber  110 , the displacement mechanism  14  is operated to return the motion rods  141  and to place the cover member  122  on the support tray  121 , and then the pod detaching mechanism  13  is operated to lock the support tray  121  and the cover member  122 . Thus, the user can then remove the pod  12  from the pod storage cabinet  3 . 
         [0030]    As indicated above, the present invention provides an inert gas filling system  1 , which has the following features and benefits: 
         [0031]    1. The invention blocks the accommodation chamber  110 , keeping it in an airtight status. Thus, an inert gas can be filled in the accommodation chamber  110  through the inert gas filling ports  113  to reduce particle-induced friction, maintaining cleanliness in the pod  12 . 
         [0032]    2. The invention uses the inert gas filling ports  113  for filling an inert gas into the accommodation chamber  110  to control pollutants of the storage item  2  by means of the motion and flowing direction of the supplied inert gas, preventing oxidization of the storage item  2 . 
         [0033]    3. The user can start the inert gas filling operation after opened the work platform  11  or the pod storage cabinet  3  and placed the pod  12  with the storage item  2  in the pod storage cabinet  3 . The operation procedure is simple and convenient. 
         [0034]    Although particular embodiments of the invention have been described in detail for purposes of illustration, various modifications and enhancements may be made without departing from the spirit and scope of the invention. For example, vacuum mounts may be provided at the carrier plate of the displacement mechanism for securing the photomask pod. Accordingly, the invention is not to be limited except as by the appended claims.