Abstract:
A Front Opening Unified Pod (FOUP) has a pair of latch structures, and the latch structures install in a door of the FOUP. The latch structures use a circular rotary turntable to drive a pair of sliding devices, let the latch structures can lock or unlock more stabilized, and use sliding rollers respectively disposed on the sliding devices to prevent the generation of dusts.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention is related to a front opening unified pod (FOUP), and more particularly, to at least one of latch structure disposed in a FOUP. 
     2. Description of the Prior Art 
     The semiconductor process consists of multiple procedures or steps, during which wafers are to be placed in different locations or different machines, and therefore in the process, wafers need to be transported from one place to another and even stored for certain period of time as required by the process flow. Wherein, wafer cassettes function both as storage containers and transportation containers and need to be compatible with different types of transportation and carrying devices and thus play a very important role in the semiconductor process. 
     As shown in  FIG. 1 , in which is a conventional front opening unified pod (FOUP). The FOUP, usually formed by one-piece injection molding, has a container body A and the inner side of the container body A is disposed with a plurality of wafer supporting pieces B; the wafer supporting pieces B and the container body A can be formed by one-piece injection molding, or the container body A can be formed with a plurality of integrated sockets by one-piece injection molding and the wafer supporting pieces B are then snap-fitted into the integrated sockets. 
     However, as the size of wafers increases, to over 300 mm for example, the size of wafer containers also needs to be increased. Yet when a large-sized wafer container is formed with injection molding using polymer material, the stress induced by the polymer material may cause distortion of the container body during its formation and may further lead to distortion of integrated wafer supporting pieces or sockets formed by one-piece injection molding; since the wafer supporting pieces or sockets are symmetrically disposed on left and right sides (for wafers to be horizontally placed in the container), slight distortion may lead to tilted position of wafers and affect the process and may even cause cracks in wafers and thus result in serious losses. 
     The door is usually disposed with retaining components that co-operates with the wafer supporting pieces to secure wafers in the container body; however, retaining components are generally fixed to the door and when the wafers placed in the container body are large-sized ones, the vibration of wafers may be stronger while being carried due to its large size, and fixed retaining components may result in lack of cushioning that causes wafers in the wafer container to crack and thus severe losses. 
     Moreover, a conventional latch structure comprises complex mechanical structures, which are more susceptible to breakdown and also friction during the process of operation that leads to contamination of wafers. 
     In addition, OHT system is usually used for carrying wafer containers, and an OHT head C (as shown in  FIG. 1 ) is usually disposed on top of wafer containers to facilitate the robot in gripping and lifting wafer containers to other process platforms. The conventional OHT head C is usually lock-fastened with a plurality of lock-fasteners disposed at its center. 
     Loaded with large-sized wafers, a large-sized FOUP weighs heavier than a conventional small-sized FOUP. As the conventional OHT head C is only lock-fastened to the FOUP with a plurality of lock-fasteners and has to sustain the weight of the large-sized FOUP and of wafers within, distortion and cracks of the upper side of the FOUP may occur easily, and the OHT head C may break loose from the large-sized FOUP, which may fall down and be damaged and thus lead to a larger cost loss. 
     Furthermore, as a large-sized FOUP is manually transported with its opening facing upward, when the FOUP is placed on a flat surface, weight of large-sized wafers in the FOUP may exert considerable impact when the FOUP and the surface are in contact and thus result in cracks or chipping of large-sized wafers in the FOUP. 
     SUMMARY OF THE INVENTION 
     In order to solve the aforementioned problems, one primary objective of the present invention is to provide a FOUP with its door disposed with a latch structure in which a circular rotary drives sliding devices for the latch structure to be securely locked and unlocked and for preventing extra vibration or accidental collision during locking and unlocking processes, wherein rollers are also employed to prevent the generation of dust. 
     According to the aforementioned objective, the present invention provides A FOUP, comprising: a container body, having an opening for importing and exporting said plurality of wafers, two opposite edges at said opening of said container body respectively disposed with at least a pair of sockets; a door, joined with said opening of said container body for protecting said plurality of wafers inside said container body, and two opposite edges of said door respectively disposed with at least a pair of latch holes corresponding to said pair of sockets; at least a pair of concave areas are disposed in said door, each of said pair of concave areas disposed with a latch structure, said latch structure comprising: a circular rotary, having a first surface and a second surface, said first surface disposed with a rotating portion and said second surface disposed with a braking portion at its central area; at least a pair of driving pieces formed on two opposite ends on periphery of said circular rotary; and a pair of sliding devices respectively disposed on two opposite sides of periphery of said circular rotary, each of said pair of sliding devices having a first end close to said circular rotary and a second end opposite to said first end, said first end formed with a hook-shaped engaging portion and a sliding portion and said second end formed with at least a latch bolt that corresponds to said latch holes of said door, wherein, said hook-shaped engaging portions hook said driving pieces for said sliding devices to be engaged with said circular rotary, and rotation of said circular rotary is controlled by said braking portion, and said latch bolts of said sliding devices are thus driven to and fro between said pair of sockets and said pair of latch holes. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same becomes better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein: 
         FIG. 1  is a view of a conventional FOUP; 
         FIG. 2  is a view of the container body of FOUP of the present invention; 
         FIG. 3  is a view of the through holes of FOUP of the present invention; 
         FIG. 4A  is a view of the supporting pieces of the present invention being disposed; 
         FIG. 4B  is a view of the supporting module of the present invention; 
         FIG. 5A  is a view of the structure of the Overhead Hoist Transport pad (OHT pad) and the Overhead Hoist Transport head (OHT head) of the present invention; 
         FIG. 5B  is a view of the structure of another embodiment of OHT pad of the present invention; 
         FIG. 6A  is a view of the base of the present invention; 
         FIG. 6B  is a view of the buckling components of the present invention; 
         FIG. 7  is a view of the rear side of the present invention; 
         FIG. 8A  is a view of the vibration-proof component of the present invention; 
         FIG. 8B  is a view of the vibration-proof component of the present invention being assembled; 
         FIG. 9  is a view of the flank portions of the present invention being assembled; 
         FIG. 10  is an explosive view of the door of the present invention; 
         FIG. 11  is a view of the outer surface of case member of the present invention; 
         FIG. 12  is a view of the retaining piece of the present invention; 
         FIG. 13  is an installation view of the retaining piece of the present invention; 
         FIG. 14  is a view of the positioning pieces of the present invention; 
         FIG. 15  is a view of the latch structure of the present invention; 
         FIG. 16  is a view of the guiding structure of the present invention; 
         FIG. 17  is a view of the retaining structure of the present invention; 
         FIG. 18A  is a view of the latch structure of the present invention when being locked; 
         FIG. 18B  is a view of the latch structure of the present invention in the process of being unlocked; 
         FIG. 18C  is a view of the latch structure of the present invention when being unlocked; 
         FIG. 19  is a view of the disposition of rubber strips of the present invention; and 
         FIG. 20  is a view of the enclosing board of the present invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     In order to make the structure and characteristics as well as the effectiveness of the present invention to be further understood and recognized, the detailed description of the present invention is provided as follows along with embodiments and accompanying figures. 
     First, referring to  FIG. 2 , which is a view of the container body of FOUP of the present invention. As shown in  FIG. 2 , the FOUP  1  comprises a container body  2  composed of left side  13 , right side  12 , upper side  10 , and lower side  11  joined with rear side  14  to form an accommodation space, an opening  15  opposite to the rear side  14 , and a door  3  sized to correspond to the size of the opening  15  of the container body  2  and to close the opening  15  of the container body  2 . 
     Then, referring to  FIG. 3 , which is a view of the through holes of wafer container of the present invention. As shown in  FIG. 3 , when a large-sized FOUP, i.e. a 450 mm FOUP or an even larger FOUP, is manufactured with injection molding, it is more difficult to control the formation of the shape of container body and distortion and deformation may occur. To prevent from deformation that results in asymmetry of supporting pieces (integrated or snap-fitting structure) on two sides of the wafer container, integrated supporting pieces (or snap-fitting structure of supporting pieces) are not formed first in the injection molding process. Instead, the wafer container is first formed by injection molding, and then an additional calibration system such as laser or other high-precision lathe bed apparatus is used to mark out symmetrical positions on the right side  12  and the left side  13  of the container body  2  and drill a plurality of first through holes  1211 ,  1231 ,  1311 , and  1331  respectively on the right side  12  near the front end  121  and the rear end  123  and on the left right  13  near the front end  131  and the rear end  133 . In one embodiment of the present invention, thirteen first through holes  1211 ,  1231 ,  1311 , and  1331  are respectively drilled on the right side  12  near the front end  121  and the rear end  123  and on the left right  13  near the front end  131  and the rear end  133 ; the number of drilled holes on each side corresponds precisely (as indicated by dotted lines), which will be described in detail in the following. What is to be emphasized here is that the number of drilled holes is not limited in the present invention and that the embodiment in which thirteen first through holes are drilled as described above is only to specifically illustrate this technical characteristic of the present invention. 
     Then, referring to  FIG. 4A , which is a view of the supporting pieces of the present invention being disposed. As shown in  FIG. 4A , the structure of the front end  121  and the rear end  123  of the right side  12  and the structure of the front end  131  and rear end  133  of the left side  13  are the same, and the first through holes  1211  and  1231  and the first through holes  1311  and  1331  on the left side  13  are also structurally the same, and the method of installing and the structure of supporting pieces  39  are also the same. Therefore, the installation of supporting pieces  30  on the rear end  131  of the left side  13  is used as a representative example and described in the following and the description of installation of supporting pieces on other sides is thus omitted. 
     Referring then to  FIG. 4A , a plurality of first through holes  1311  are disposed near the front end  131  of the left side  13  of the container body  2 , wherein, the embodiment of the present invention as described has thirteen first through holes  1311 . As shown in  FIG. 4A , a positioning frame  20  is formed with a plurality of second through holes  201 , and each of the plurality of second through holes  201  is formed and positioned by precise processing; for example, in the embodiment of the present invention, the positioning frame  20  is formed with thirteen second through holes  201 , and the second through holes  201  are disposed in correspondence to the first through holes  1311  for the positioning frame  20  to be lock-fastened to the outer side of left side  13  of the container body  2  near the front end  131 . In one embodiment, there are in total thirteen first through holes  1311  as described above, and the three first through holes  1311 ′ that are respectively positioned at top, middle, and bottom are to receive the first lock-fasteners  50  that lock-fasten the positioning frame  20 . In addition, the material of the positioning frame  20  can be metal or engineering plastic. 
     Then, referring to  FIG. 4B , which is a view of the supporting module of the present invention. As shown in  FIG. 4B , the plurality of supporting modules  30  have a plurality of protruding lock-fastening holes  301  formed on one side and a plurality of ribs  303  horizontally arranged at intervals formed on another side. The protruding lock-fastening holes  301  of each supporting module  30  penetrate each of the rest of the second through holes  201  on the positioning frame  20  and each of the rest of the first through holes  1311  at the front end  131  of the left side  13  of the container body  2 , and each supporting module  30  is then fastened to the inner left side  13  near the front end  131  with a plurality of second lock-fasteners  52 . A seal ring  40  can be further disposed on the lock-fastening holes  301  of each supporting module  30  to achieve air-tightness in the FOUP  1 . 
     In an embodiment of the present invention, each end is respectively disposed with five supporting modules  30 , and each of the supporting modules  30  has two lock-fastening holes  301  and five ribs  303 ; therefore, there are ten lock-fastening holes  301  and twenty-five ribs  303  in total, and the ten lock-fastening holes  301  can be respectively received by the rest of the first through holes  1311  of the container body  2  and the rest of the second through holes  201  on the positioning frame  20 . What is to be emphasized here is that the number of the first through holes  1311  and the number of the second through holes  201  are not limited in the present invention, both numbers being determined by the number of the supporting modules  30  disposed and the number of the positioning frames  20  to be lock-fastened. And then, with the four ends, the front end  121  and rear end  123  of the right side  12  and the front end  131  and rear end  133  of the left side  13 , being respectively disposed with supporting modules  30 , each supporting module  30  corresponding to each of the four ends is loaded with five wafers; apparently, in one embodiment of the present invention, there are five sets (four ends as a set) of supporting modules  30  in the accommodation space in the container body  2 , and thus twenty-five wafers in total can be loaded; what is to be emphasized is that the number of wafers placed in the accommodation space in the container body  2  is not limited in the present invention. 
     Then, referring to  FIG. 5A , which is a view of the structure of the Overhead Hoist Transport pad and the Overhead Hoist Transport head of the present invention, and in the following description, the Overhead Hoist Transport pad will be referred to as “OHT pad” and the Overhead Hoist Transport head will be referred to as “OHT head.” As shown in  FIG. 5A , a protruding member  101  is formed on the upper side  10  of the container body  2 , a ring-shaped snap-fitting groove  103  is formed around the protruding member  101  on the upper side  10 , and a plurality of first studs  105  are formed between the snap-fitting groove  103  and the protruding member  101 ; then, an OHT pad  60  and an OHT head  62  are further disposed on the upper side  10  of the container body  2 , wherein, the OHT pad  60  is disposed on the upper side  10  of the container body  2 , a through hole  601  is formed at the center of the OHT pad  60 , and a plurality of protruding second studs  603  are formed around the through hole  601 ; the second studs  603  can be in the form of through holes, which is not limited in the present invention. These second studs  603  correspond to the plurality of first studs  105 . A snap-fitting piece  605  corresponding to the snap-fitting groove  103  on the upper side  10  can be further formed around the OHT pad  60 . Moreover, a round mortise member  621  is formed at the center of the OHT head  62 , a plurality of protruding third through holes  623  are formed on one side, and the third through holes  623 , the second studs  603 , and the first studs  105  are correspondingly disposed. Then, after the round mortise member  621  of the OHT head  62  penetrates the through hole  601  of the OHT pad  60  and then engages with the protruding member  101 , the snap-fitting piece  605  of the OHT pad  60  is then snap-fitted to the snap-fitting groove  103  on the upper side  10 , the second studs  603  on the OHT pad  60  and the plurality of first studs  105  on the upper side  10  of the container body  2  and the third through holes  623  on the OHT head  62  are aligned, and a plurality of third lock-fasteners  54  are used to lock-fasten the second studs  603  and the third through holes  623  to the plurality of first studs  105  on the upper side  10  of the container body  2  for joining together the OHT pad  60 , the OHT head  62 , and the upper side  10  of the container body  2 . 
     The primary function of adding the OHT pad  60  in the present invention is to distribute the weight sustained by the OHT head  60  when the robot transports the FOUP. The OHT head of a conventional FOUP is lock-fastened to the wafer container with a plurality of lock-fasteners. Yet as far as a larger-sized FOUP is concerned, with the OHT head lock-fastened to the container body only with a plurality lock-fasteners, it is difficult for the OHT head to sustain the weight of the FOUP and twenty-five wafers placed within when the FOUP is lifted and transported during semiconductor process in the semiconductor fabrication plant. Therefore, with the structure of an OHT pad  60 , the present invention is able to distribute the weight of the FOUP and twenty-five wafers placed within sustained by the OHT head. Apparently, the present invention provides a snap-fitting structure comprising the snap-fitting piece  605  of the OHT pad  60  and the snap-fitting groove  103  of the upper side  10  that evenly distributes the weight; with the plurality of protruding second studs  603  on the OHT pad  60  and the plurality of third through holes  623  of the OHT head  62  being lock-fastened together via the third lock-fasteners  54 , the OHT head  62  can be more securely lock-fastened to the plurality of first studs  105  on the upper side  10  of the container body  2 , and with the round mortise member  621  at the center of the OHT head  62  being disposed in the rear of the center of gravity of the FOUP  1  and the round mortise member  621  being engaged with the protruding member  101  of the upper side  10  of the container body  2 , the OHT head  62  can be kept balanced without vibration. In addition, the material of the OHT pad  60  of the present invention can be engineering plastic of high hardness, and more particularly, the hardness of material of the OHT pad  60  is higher than that of the material of the container body. 
     And then, referring to  FIG. 5B , which is a view of the structure of another embodiment of OHT pad  60  of the present invention. As shown in  FIG. 5B , OHT pad  60  is formed on the upper side  10  of the container body  2  with embedded injection molding, a protruding member  607  is formed at the center of OHT pad  60 , and a plurality of protruding undercut mortise members  609  are formed around the protruding member  607 ; an OHT head  62  is disposed with a round mortise member  621  formed at the center, and a plurality of protruding third through holes  623  are formed on one side, wherein the third through holes  623  and the undercut mortise members  609  are correspondingly disposed; a plurality of third lock-fasteners  54  are used to lock-fasten the undercut mortise members  609  with the third through holes  623  for joining together the OHT pad  60  and the OHT head  62 ; wherein, the round mortise member  621  of the OHT head  62  engages the protruding member  607  of the OHT pad  60 . 
     The OHT pad  60  of the present embodiment is formed on the upper side  10  of the container body  2  with embedded injection molding, and thus the design of the snap-fitting piece  605  and the snap-fitting groove  103  as shown in  FIG. 5A  is not needed. Moreover, as the OHT pad  60  is formed with the container body  2  by embedded injection, the situation in which the OHT pad  60  breaks loose from the container body  2  can be avoided, and such structure can distribute the weight of FOUP and twenty-five wafers sustained by the OHT head more evenly. 
     Referring to  FIG. 6A , which is a view of the base of the present invention. As shown in  FIG. 6A , a first ventilation hole  111  is respectively formed at each of the four corners of the lower side  11  of the container body  2 , and a base  70  is further disposed below the FOUP  1 ; wherein, a plurality of second ventilation holes  701  are formed on the base  70 , and each of the second ventilation holes  701  and each of the first ventilation holes  111  are correspondingly disposed. 
     Then, referring to  FIG. 6B , which is a view of the buckling components of the present invention. As shown in  FIG. 6B , a plurality of buckling components comprise first components  80  having inner teeth and second components  82  having outer teeth. The inner teeth  801  of each of the first components  81  penetrate each of the first ventilation holes  111 , and the outer teeth  821  of each of the second components  82  penetrate each of the second ventilation holes  701 . Therefore, with the Inner teeth  801  and the outer teeth  821  being engaged, the first components  81  and the second components  82  are joined for the base  70  and the lower side  11  of the container body  2  to be joined together. 
     The buckling components of the present invention can also be snap-fitting pieces with a hollow structure, and thus, after the base  70  and the lower side  11  of the container body  2  are joined together via the snap-fitting pieces, the hollow structure is disposed with a purging valve (or an exhausting valve) for the base  70  to be equipped with purging (or exhausting) function after being joined together with the lower side  11  of the FOUP; and a seal ring  42  can be further disposed on each of the first components  80  or the second components  82  to achieve air-tightness in FOUP  1 . 
     Referring then to  FIG. 7 , which is a view of the rear side of the present invention. As shown in  FIG. 7 , on the rear side  14  of the FOUP of the present invention, a rear opening  141  opposite to the opening  15  can be further formed; an objective of forming this rear opening  141  is to facilitate the calibration and measurement of the semiconductor equipment. And at the rear opening  141 , a flat piece  90  can be embedded in the rear opening  141 , wherein the flat piece  90  can be transparent or opaque. In one embodiment of the present invention, the flat piece  90  is embedded in the rear opening  141  of the container body  2  via ultrasonic welding; however, the method of embedding or joining the flat piece  90  is not limited in the present invention. Moreover, the material of flat piece  90  of the present invention can be anti-UV engineering plastic material of high cleanliness, and similarly, the material of flat piece  90  is not limited in the present invention. Furthermore, scales and letters such as numbers, process stages, and barcodes can be marked on the transparent flat piece  90  to facilitate the operation of the process. 
     Referring to  FIG. 8A , which is a view of the vibration-proof component of the present invention. As shown in  FIG. 8A , a vibration-proof component  17  is respectively disposed behind the container body  2  of the FOUP  1 , on the right side  12  and the left side  13 , and at the corners where the two sides join the rear side  14 . The vibration-proof component  17  comprises a connecting piece  171  and a vibration-proof pad  173 , wherein the connecting piece  171  is fixed to the container body  2  via a lock-fastening structure (not shown in Figure), and the vibration-proof pad  173  is fixed to the connecting piece  171  via a snap-fitting structure (not shown in Figure). The vibration-proof component  17  mainly functions to prevent from collisions during the transportation process. Moreover, when a large-sized FOUP is manually transported, the opening of FOUP faces upward during the transportation process, and thus the vibration-proof pad  173  also offers a non-slip function to ensure that displacement of wafers in the FOUP  1  does not occur due to horizontal carriage movement when the FOUP  1  is transported. 
     The vibration-proof pad  173  of the vibration component  17  may wear after long-term usage, and therefore the snap-fitting structure (not shown in Figure) fixing the vibration-proof pad  173  to the connecting piece  171  facilitates the replacement of vibration-proof pad  173 . What is to be emphasized here is that, the connecting piece  171  in the present embodiment is fixed to the container body  2  via a lock-fastening structure (not shown in Figure) and the vibration-proof pad  173  is fixed to the connecting piece  171  via a snap-fitting structure (not shown in Figure), yet the method for joining and fixing is not limited in the present invention. Moreover, the material of vibration-proof pad  173  in the present embodiment is elastic rubber but is not limited in the present invention and any other material that offers collision-proof and non-slip functions is regarded as within the scope of the present invention. 
     Then, referring to  FIG. 8B , which is a view of the vibration-proof component of the present invention being assembled. As shown in  FIG. 8B , after the assembly of vibration-proof component  17  is completed, the vibration-proof component  17  protrudes out of the container body  2 ; therefore, when the container body  2  collides with the floor or a wall, direct contact between the container body  2  and the collided object can be avoided and the wafers within can be protected. 
     Then, referring to  FIG. 9 , which is a view of the flank portions of the present invention being assembled. The flank structure is a part of standard structure required by SEMI standards and the function of which is for the robot to move the whole FOUP via the flank structure. As shown in  FIG. 9 , a flank portion  16  is respectively disposed on the outer side of right side  12  and the outer side of left side  13  for the container body  2  to correspond to SEMI standards. The flank portions  16  are to reinforce the structure of the container body  2  and prevent the container body  2  from deforming due to the stress induced by the material when being formed with one-piece injection molding, so the flank portions  16  are disposed on the outer side of right side  12  and the outer side of left side  13  of the container body  2  after the container body  2  is formed; the assembling method of the flank portions  16  with the container body  2  is not limited in the present invention. 
     Then, referring to  FIG. 10 , which is an explosive view of the door of the present invention. As shown in  FIG. 10 , the door  3  comprises a case member  300  and an enclosing board  310  having an outer surface  3101 . The case member  300  has an outer surface of the case member  3001  opposite to the opening  15  and an inside surface of the case member  3006  (please refer to  FIG. 15 ). The outer surface of the case member  3001  has a concave area  3005  and two first platforms  3008 . The concave area  3005  is disposed in the middle of the outer surface of the case member  3001 . The two first platforms  3008  are disposed in the outer surface of the case member  3001  and respectively located at two side of the concave area  3005 . The outer surface of the case member  3001  further has an inclined area  3003  between each of the two first platform  3008  and the concave area  3005 , and a connection position between the inclined area  3003  and the first platforms  3008  is higher than a connection position between the inclined area  3003  and the concave area  3005 . The outer surface of the case member  3001  is disposed with a pair of elastic retaining structures  100  to retain wafers in the FOUP, the method of which will be described in detail in the following; in addition, a pair of latch structures  500  are disposed in the case member  300 , and with the assembly of the case member  300  and the enclosing board  310 , the pair of latch structures  500  are also located within the door  3 ; wherein each of the latch structures  500  has a latch bolt  60031  that corresponds to the latch holes  3002  on the case member  300  and the sockets  107  on the container body  2  (please refer to  FIG. 2 ). 
     Referring to  FIG. 11 , which is a view of the outer surface of case member of the door of the present invention. As shown in  FIG. 11 , a pair of inclined areas  3003  are disposed on two sides of the concave area  3005  of the outer surface of case member  3001  and slanted in relation to the concave area  3005  of the outer surface of case member  3001  with a distance between the pair of inclined areas  3003  disposed opposite each other, wherein a curved structure is formed between the pair of inclined areas  3003  and the concave area  3005  of the outer surface of case member  3001 , and an elastic retaining structure  100  is respectively disposed on each bevel; the elastic retaining structure  100  comprises: a first clip bar  1001 , which is disposed on the bottom end  30031  of the inclined area  3003  near the concave area  3005  and has a plurality of first slots  10011 , a second clip bar  1003 , which is disposed on the top end  30033  of the inclined area  3003  near the outer surface of case member  3001  and has a plurality of second slots  10031 , and a retaining piece  200 , which is disposed between the first clip bar  1001  and the second clip bar  1003 ; moreover, a plurality of ribs  30051  are further added in the concave area  3005  to reinforce the structure of the door  3 . 
     Referring then to  FIG. 12 , which is a view of the retaining piece of the present invention. As shown in  FIG. 12 , the retaining piece  200  comprises: a long spring piece  2001 , which has a first end  20011  and a second end  20013  opposite to the first end  20011 , a long V-shaped piece  2005 , and a S-shaped spring piece  2003  that is respectively connected to the long spring piece  2001  and the long V-shaped piece  2005 ; in a most embodiment of the present invention, a retaining module is composed of five retaining pieces  200  and five retaining modules corresponding to the supporting modules  30  in the container body  2  are disposed; the number of the assembly of retaining pieces  200  is not limited in the present invention. 
     Referring then to  FIG. 13 , which is an installation view of the retaining piece of the present invention. As shown in  FIG. 13 , the retaining piece  200  is disposed between the first clip bar  1001  and the second clip bar  1003 , and the first end  20011  of the long spring piece  2001  of the retaining piece  200  is inserted into the first slot  10011  of the first clip bar  1001 ; the installation is completed when the second end  20013  of the long spring piece  2001  is inserted into the second slot  10031  of the second clip bar  1003 . 
     When wafers  4  are placed in the container body  2  and the door  3  is closed, the retaining pieces  200  disposed on the outer surface of case member  3001  of the door  2  snap-fit the wafers  4 , and the long V-shaped pieces  2005  of the retaining pieces  200  snap-fit the wafers  4  in the V-shaped structure and keep each of the wafers  4  in the container body separated from each other; while the wafers  4  are placed in the container body  2  with the door  3  closed, the retaining pieces  200  are compressed by the wafers  4 , and since the long spring pieces  2001  and the S-shaped spring pieces  2003  are elastic structures, they can generate and exert a clamping force on the wafers  4 , and therefore, with the S-shaped spring pieces  2003 , the retaining pieces  200  can sway sideways to exert a clamping force both vertically and from the left and right sides during vibration (i.e. transportation process) and can also prevent wafers  4  from spinning to ensure the stability and safety of wafers  4 . Moreover, the curved structure formed between the inclined areas  3003  and the concave area  3005  of the outer surface of case member  3001  can form an accommodation space when retaining pieces  200  are compressed by the wafers  4 ; the curved structure helps reduce the volume and weight of the door  3 . 
     Then, refer to  FIG. 14 , which is a view of the positioning pieces of the present invention. As shown in  FIG. 14 , a positioning piece  400  is respectively disposed at the joint where the bottom end  30031  of the inclined area  3003  opposite the outer surface of case member  3001  connects the central area  305 , wherein each of the positioning pieces  400  has a gap  4001  corresponding to the V-shaped structure of the long V-shaped piece  2005 ; therefore, when a wafer is placed in the V-shaped structure of the long V-shaped piece  2005 , it is also accommodated by the gap  4001  of the positioning piece  400 ; as the wafer may vibrate up and down during the transportation process, the gap  4001  of the positioning piece  400  prevents the wafer from going up and down when being carried and further stabilizes the wafer; in an embodiment of the present invention, five positioning piece modules respectively composed of five positioning pieces are disposed and correspond to the retaining modules disposed on the door  3 , wherein the number of assembly of positioning pieces  400  is not limited in the present invention. 
     Referring then to  FIG. 15 , which is a view of the latch structure of the present invention. As shown in  FIG. 15 , the inside surface of the case member  3006  has two second platforms  3007 , and the two second platforms  3007  are respectively located in two side of the inside surface of the case member  3006  and opposite to the two first platforms  3008 . Each of the pair of the latch structures  500  comprises: a circular rotary  5001 , which has a first surface  50011  facing the inside surface of the case member  3006  and a second surface  50013  facing the enclosing board  310 , the first surface  50011  being disposed with a rotating portion  5002  and the center of the second surface  50013  being disposed with a braking portion  5003 , a pair of driving pieces  5004 , which are formed on two opposite ends on the periphery of the circular rotary  5001 , a pair of sliding devices  600 , which are respectively disposed on two opposite sides of the periphery of the circular rotary  5001 , each sliding device  600  having a first end  6001  close to the circular rotary  5001  and a second end  6003  opposite to the first end  6001 , the first end  6001  being formed with a hook-shaped engaging portion  60011  and a sliding portion  60013  and the second end  6003  being formed with a latch bolt  60031  that corresponds to the latch holes  3002  of the door  3 , wherein the hook-shaped engaging portions  60011  hook the driving pieces  5004  for the sliding devices  600  to be engaged with the circular rotary  5001 ; the driving piece  5004  can be a bearing device but is not limited in the present invention, and the driving piece  5004  can be further disposed with a buckle  5005 , which functions to prevent the driving piece  5004  from breaking loose. 
     A plurality of bolt rollers  60033  are disposed at the end of the latch bolt  60031  and facilitate the sliding of the latch bolt  60031  when it is inserted into the sockets  107  of the container body  2  to prevent it from getting stuck; moreover, the sliding device  600  is further disposed with a first sliding roller  6005  and a second sliding roller  6007 ; what is to be emphasized here is that, a first sliding roller  6005  and a second sliding roller  6007  are disposed on the sliding device  600  in the present embodiment of the invention, but the number of the sliding roller is not limited in the present invention. A first guiding structure  700  is further disposed where the first sliding roller  6005  is located and a second guiding structure  710  is further disposed where the second sliding roller  6007  is located; the first guiding structure  700  and the second guiding structure  710  are disposed to frame each sliding device  600  within the second platform  3007  and to prevent the sliding device  600  of the latch structure  500  from swaying sideways, the material of the guiding structures are a wear-resistant material. 
     Then, refer to  FIG. 16 , which is a view of the guiding structure of the present invention. As shown in  FIG. 16 , a first track  7001  is disposed under the first guiding structure  700 , and a first clamping piece  7003  is disposed above the first track  7001 , wherein the first clamping piece  7003  keeps the first sliding roller  6005  along the first track  7001  and prevents it from swaying sideways; a second track  7101  is disposed above the second guiding structure  710 , and a second clamping piece  7103  is disposed under the second track  7101 , wherein the second clamping piece  7103  keeps the second sliding roller  6007  along the second track  7001  and prevents it from swaying sideways; what is to be emphasized is that, the first track  7001  under the first guiding structure  700  and the second track  7101  above the second guiding structure  710  are used in the present invention to retain and prevent the sliding device  600  from swaying sideways, but neither the number nor the position of track is limited in the present invention; an embodiment in which tracks are disposed both above and under the first guiding structure  700  and the second guiding structure  710  is also an embodiment of the present invention. 
     Referring then to  FIG. 17 , which is a view of the retaining structure of the present invention. As shown in  FIG. 17 , the latch structure  500  is further disposed with a retaining structure  800 , which comprises: a pair of retaining axles  8001  respectively disposed on two sides of the braking portion  5003  of the circular rotary  5001  and an elastic retaining frame  8003 , which has a pair of fixed portions  80031  on two opposite ends and a pair of retaining frames  80033  respectively connected to the fixed portions  80031 , wherein the pair of fixed portions  80031  are fixed to the second platform  3007  of the case member  300 , and the pair of retaining frames  8003  retain the pair of retaining axles  8001  within them and are curved elastic structures; moreover, the retaining axles  8001  can be further disposed with a buckle  8005 , which functions to retain the retaining axles  8001  and prevent them from breaking loose. 
     And referring then to  FIGS. 18A to 18C , which are views of the latch structure of the present invention in operation. First, as shown in  FIG. 18A , when the door  3  locks the container body  2 , the latch bolt  60031  of the sliding device  600  inserts into the sockets  107  of the container body  2  via the latch holes  3002  on the case member  300 , and meantime the driving pieces  5004  that are at the position of the sliding portion  60013  push the sliding portion  60013  to drive the sliding devices  600  to be securely fitted into the sockets  107 , and the retaining axles  8001  snap-fit to the curved elastic structure of the retaining frames  8003  at the position X. 
     Then, as shown in  FIG. 18B , when the door  3  is to be opened, the unlocking piece (not shown in Figure) is inserted into the braking portion  5003  of the circular rotary  5001  and turned clockwise, and meantime the retaining axles  8001  on the circular rotary  5001  rotate as well and prop open the retaining frames  8003 ; the retaining frames  8003  are elastic and also sturdy to a certain degree, and therefore the retaining axles  8001  will not be displaced when they snap-fit at the aforementioned position X due to the sturdiness of the retaining frames  8003 ; and when the unlocking piece (not shown in Figure) turns the circular rotary  5001 , the retaining axles  8001  will prop open the elastic retaining frames  8003  due to the exertion of external force but without damaging the retaining frames  8003 . 
     And then as shown in  FIG. 18C , when the door  3  is opened, the circular rotary  5001  is rotated 45° clockwise, the driving pieces  5004  slide into the position of the hook-shaped engaging portions  60011  along the sliding portions  60013  and thus drive the sliding devices  600  to draw in and lead the latch bolt  60031  to slide out of the sockets  107  of the container body  2  for the latch structure  500  of the door  3  to be disengaged from the container body  2 ; in addition, the retaining axles  8001  move from the position X via the position Y to the position Z, the retaining frames  8003  snap back to their original, size when being retained, and the retaining axles  8001  snap-fit at the position Z. 
     Referring to  FIG. 19 , which is a view of the disposition of rubber strips of the present invention. As shown in  FIG. 19 , a rubber strip  30071  surrounding the concave area  3007  is disposed on the periphery of the concave area  307  of the case member  300 ; when the case member  300  and the enclosing board  310  are joined with each other, the rubber strip  30071  disposed on the periphery of the concave area  307  will tightly adhere to the enclosing board  310  and the concave area  307  will thus be isolated from other parts of the case member  300  and form an enclosed area, wherein only the latch holes  3002  on the case member  300  are not closed. 
     As the door  3  will be constantly opened and closed when the FOUP  1  is used in the process, even if the material of the guiding structures in the door  3  is a wear-resistant material, particles or dust will still be generated due to friction after the sliding devices  600  slide for multiple times, and therefore the latch structure  500  disposed within needs to be cleaned. Thanks to the enclosed area formed as described above, a cleaning solvent (such as water) can be instilled via the upper latch hole  3002  and expelled via the lower latch hole  3002  without seeping into other parts of the door  3  since the rubber strip  30071  already forms an enclosed area, whereby the door  3  can dry faster after being cleaned and the cleaning process can also become more convenient. 
     Referring then to  FIG. 20 , which is a view of the enclosing board of the present invention. As shown in  FIG. 8 , a plurality of door-side rollers  900  are disposed at the edge of the enclosing board  310 , and a snap-hook structure  910  is disposed behind the door-side rollers  900 ; a plurality of roller grooves  3009  corresponding to the door-side rollers  900  are disposed at the edge of the case member  300 , and a snap-hook groove  30091  corresponding to the snap-hook structure  910  is disposed below the roller grooves  3009 . When the enclosing board  310  and the case member  300  are joined with each other, the door-side rollers  900  are placed in the roller grooves  3009  and the snap-hook structure  910  is embedded in the snap-hook groove  30091  for engaging the enclosing board  310  and the case member  300  with each other, wherein the door-side rollers  900  function to help the door  3  slide smoothly onto the container body  2  when the container body  2  is closed by the door  3  and avoid accidental collision. Furthermore, a pair of lock holes  3103  corresponding to the braking portions  5003  of the latch structure  500  are disposed on the enclosing board  310 ; when the enclosing board  310  and the case member  300  are joined with each other, the unlocking piece (not shown in Figure) can be inserted via the lock holes  3103  into the braking portions  5003  of the circular rotary  5001  for the unlocking task to be performed. 
     While the invention has been described by way of examples and in terms of the embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. To the contrary, it is intended to cover various modifications and similar arrangements as would be apparent to those skilled in the art. Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.