Abstract:
An EUV pod with fastening structure comprises an outer pod and an inner pod, wherein the upper cover of the inner pod is disposed with a plurality of retainers, and a plurality of supporters disposed on the outer pod of the EUV pod are used to press the plurality of retainers for the plurality of retainers to fasten and stabilize the reticle in the inner pod and thus ensure safety and stability of the reticle in the pod; by utilizing such design, risks of collisions of reticle in the pod due to vacillation of EUV pod during transportation can be reduced, and cost incurred by cracks and damages of reticles can also be greatly decreased.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
       [0001]    This application claims priority to Taiwan Patent Application No. 100101022, filed Jan. 11, 2011, the contents of which are hereby incorporated by reference in their entirety. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention is related to a reticle pod, and more particularly, to an EUV pod with fastening structure. 
         [0004]    2. Description of the Prior Art 
         [0005]    In the rapidly developing modern semiconductor technology, optical lithography tool plays an important role. The pattern definition relies fully on optical lithography technology. In the application of optical lithography tool related to semiconductors, pre-designed circuit paths are fabricated as light-transparent reticle in specific form. Basing on the principle of exposure, after light from the light source passes through the reticle and is projected on a silicon wafer, specific circuit pattern can be exposed on the silicon wafer. However, since any kind of dust (such as particles, powders, and organic matters) that adhere to the reticle can result in quality degradation of projected pattern, the reticle used to produce pattern on silicon wafers is required to be kept absolutely clean. Therefore, a cleanroom environment is usually provided in ordinary wafer fabrication processes to prevent from contamination caused by particles in the air. 
         [0006]    In recent years, in order to further scale down the chip feature sizes, EUV (extreme ultraviolet light) at a wavelength of 157 nm is applied in lithography tool for the pattern on reticle to be imaged with higher resolution when being projected on the surface of a silicon wafer. However, when EUV is applied, the requirements for cleanliness of reticle pod are also, relatively speaking, higher. Particles smaller than 30 μm are previously acceptable, but as far as reticle pods for use with EUV lithography techniques are concerned, only particles with sizes between 30 and 50 nm are acceptable. 
         [0007]    As a result, anti-contamination reticle pods are used in modern semiconductor process to store and carry reticles and to maintain the cleanliness of reticles; on the other hand, anti-contamination storage containers for semiconductor components are also used for storing and carrying semiconductor components and also for maintaining the cleanliness of semiconductor components. Reticle pods are used in the semiconductor process for storing reticles and for facilitating the carrying and transporting of reticles between platforms in order to isolate reticles from the air and thus prevent haze from forming on the surface of reticles due to contamination of reticles caused by particles and chemical gas. Thus, in advanced semiconductor plants, the cleanliness of reticle pods or storage devices for semiconductor components is usually required to comply with the SMIF (Standard Mechanical Interface) standard, in other words, to be maintained at Class 1 or below. 
         [0008]    In order to reduce contamination generated during the process of storing, manufacturing, and transporting, a technology that uses a double-layer container for isolating the reticle has been proposed in the prior art, wherein an inner container is used for carrying the reticle and an outer container is used for fastening the inner container therein. As shown in  FIG. 8 , the lower cover c and the upper cover d of an inner container cover the reticle e and fasten the reticle e within the inner container, and then the lower cover a and the upper cover b of an outer container cover the inner container and fasten the inner container within the outer container. In the double-layer pod structure, supporters disposed in an outer container are usually used for fastening the inner container. However, in such double-layer pod structure, the user is unable to determine whether the inner container is stably snap-fastened by the supporters of the outer container and is unable to make sure the positioning status of the reticle in the inner container either. In consideration of the aforementioned, the present invention provides a reticle pod in which supporters of the outer container are used to press retainers of the inner container and thus indirectly fasten the reticle inside for ensuring safety and stability of the reticle in the reticle pod. 
       SUMMARY OF THE INVENTION 
       [0009]    In order to solve the above-mentioned problem, one primary object of the present invention is to provide a reticle pod, in which supporters disposed on the outer container are used to press retainers of the inner container for indirectly fastening reticle inside the pod and thus ensuring the safety and stability of the reticle inside. 
         [0010]    Another primary object of the present invention is to provide a reticle pod, in which supporters disposed on the outer container are used to press retainers of the inner container for preventing the inner container from shifting and further ensuring the safety of the reticle inside the inner container. 
         [0011]    According to the objectives above, the present invention provides a reticle pod, in which a reticle is fastened in an inner container and the inner container is placed in an outer container; the outer container comprises: a lower cover of outer container having a first inner surface on which a plurality of first supporters are formed, and an upper cover of outer container having a second inner surface on which a plurality of second supporters are formed, a first accommodation space being formed by the first inner surface and the second inner surface for accommodating the inner container when the lower cover and the upper cover of the outer container are joined together; the inner container comprises: a lower cover of inner container placed in the first accommodation space and in contact with the plurality of first supporters, the lower cover of inner container having a first inner surface of inner container, and an upper cover of inner container placed in the first accommodation space, the upper cover of inner container having a second inner surface of inner container and an outer surface of upper cover of inner container on the opposite side of the second inner surface of inner container, a second accommodation space being formed by the first inner surface of inner container and the second inner surface of inner container for accommodating the reticle when the lower cover of the inner container and the upper cover of the inner container are joined together; wherein, the characteristic of the upper cover of inner container is in that: a plurality of through holes are formed between the second inner surface and the outer surface of the upper cover of inner container, and an O-shaped recess is formed around each of the through holes to surround each of the through holes, a spring element being formed in each of the O-shaped recesses; a plurality of retainers are disposed in each of the through holes and their positions correspond to each of the second supporters of the upper cover of outer container, each retainer being formed by a supporting convex pillar and an corresponding O-shaped protruding portion disposed in O-shaped recess, the length of supporting convex pillar being larger than the length of O-shaped protruding portion and the supporting convex pillar and the O-shaped protruding portion are an integrated structure, wherein each O-shaped protruding portion is in an O-shaped recess and in contact with a spring element. 
         [0012]    By utilizing the design provided by the present invention, the reticle can be stably fastened in the inner container of the reticle pod and the inner container can also be fastened. The effect of fastening both the reticle and the inner container is thus achieved. Therefore, not only the risks of collisions of reticle in the pod due to vacillation of reticle pod during transportation can be reduced, but the cost incurred by cracks and damages of reticles can also be greatly decreased. 
         [0013]    Still another primary object of the present invention is to provide a reticle pod, in which the window disposed on the inner container of the reticle pod is used for monitoring the condition of the interior of the inner container. 
         [0014]    Therefore, according to the object above, the present invention provides a reticle pod, in which a reticle is fastened in an inner container and the inner container is placed in an outer container; the outer container comprises: a lower cover of outer container having a first inner surface on which a plurality of first supporters are formed, and an upper cover of outer container having a second inner surface on which a plurality of second supporters are formed, a first accommodation space being formed by the first inner surface and the second inner surface for accommodating the inner container when the lower cover and the upper cover of the outer container are joined together; the inner container comprises: a lower cover of inner container placed in the first accommodation space and in contact with the plurality of first supporters, the lower cover of inner container having a first inner surface of inner container, and an upper cover of inner container placed in the first accommodation space, the upper cover of inner container having a second inner surface of inner container and an outer surface of upper cover of inner container on the opposite side of the second inner surface of inner container, a second accommodation space being formed by the first inner surface of inner container and the second inner surface of inner container for accommodating the reticle when the lower cover of the inner container and the upper cover of the inner container are joined together; wherein, the lower cover of inner container is further disposed with a plurality of windows, each of the windows comprising: a transparent substrate, which is disposed on the window via the first inner surface of inner container, and a third retainer, which is a frame-shaped member with its size fitting the window and is disposed on the window and the transparent substrate via the first inner surface of inner container for fastening the transparent substrate. 
         [0015]    By using the design provided by the present invention, when the inner container storing a reticle is introduced into the manufacturing process, the reticle inside can be monitored through the window from the platform for ensuring that the reticle inside is correctly positioned and thus preventing cracks of reticles from occurring during the process of transferring. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]      FIG. 1  is an explosive view of the reticle pod of the present invention; 
           [0017]      FIG. 2  is a view of the retainer of the upper cover of inner container of the present invention; 
           [0018]      FIG. 3  is a view of the filter device of the upper cover of inner container of the present invention; 
           [0019]      FIG. 4  is a view of the foolproof structure of the upper cover of inner container of the present invention; 
           [0020]      FIG. 5  is a view of the limiter of the lower cover of inner container of the present invention; 
           [0021]      FIG. 6  is a view of the window of the lower cover of inner container of the present invention; 
           [0022]      FIG. 7  is a sectional view of the reticle pod of the present invention; 
           [0023]      FIG. 8  is a view of the reticle pod of the prior art. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0024]    As the present invention discloses a reticle pod, and more particularly, a reticle pod with fastening/retaining structure; the inner container, outer container, and the filtering material employed in the embodiments of reticle pod of the present invention are achieved by using current technologies and the description of which is thus omitted. Moreover, the drawings referred to in the following description are not made according to the actual scale and only function as illustrations demonstrating characteristics of the present inventions. 
         [0025]    First, referring to  FIG. 1 , which is an explosive view of the reticle pod of the present invention. As shown in  FIG. 1 , the reticle pod comprises an outer container  1  and an inner container  2 , wherein the outer container  1  comprises a lower cover of outer container  10  having a first inner surface  101  on which a plurality of first supporters  30  are formed, and an upper cover of outer container  12  having a second inner surface  121  on which a plurality of protruding second supporters  32  are formed, a first accommodation space  100  being formed between the first inner surface  101  and the second inner surface  121  for accommodating and fastening the inner container  2  when the lower cover of outer container  10  and the upper cover of outer container  12  are joined together; the inner container  2  comprises a lower cover of inner container  20 , which is placed in the first accommodation space  100  and in contact with the plurality of first supporters  30  and has a first inner surface of inner container  201 , and an upper cover of inner container  22 , which is placed in the first accommodation space  100  and has a second inner surface of inner container  221  and an outer surface of upper cover of inner container  223  which is on the opposite side of the second inner surface of inner container  221 , a second accommodation space  200  being formed between the first inner surface of inner container  201  and the second inner surface of inner container  221  for accommodating a reticle  9  when the lower cover of inner container  20  and the upper cover of inner container  22  are joined together. 
         [0026]    Furthermore, four sides of the lower cover of outer container  10  are disposed with a plurality of drain holes  105 , which are shown as round holes in  FIG. 1 ; and a pair of lock holes  103 , which are shown as rectangular holes in  FIG. 1 , are further disposed on two opposite sides among four sides of the lower cover of outer container  10 . Apparently, as the lower cover of outer container  10  is disposed with a latch (not shown in Figure), when the latch is turned to close the outer container, the latch projects into the lock holes  103 . An objective of disposing a plurality of drain holes  105  is as thus: after the lower cover of outer container  10  of the reticle pod of the present invention is cleaned with water, water molecules remaining in the lower cover of outer container  10  can be drained out through the plurality of drain holes  105  after heating and baking processes are performed, and the rate of reticle contamination caused by the reticle pod can therefore be decreased. 
         [0027]    Then, referring to  FIG. 2 , which is a view of the retainer of the upper cover of inner container of the present invention. As shown in  FIG. 2 , a plurality of through holes  225  are disposed between the second inner surface  221  and the outer surface of upper cover  223  of the upper cover  22  of the inner container of the reticle pod; in addition, an O-shaped recess  2251  is formed as surrounding each of the through holes  225  and is disposed with a spring element  42 . Moreover, a retainer  40  is disposed in each of the through holes  225 . The retainer  40  is formed by a supporting convex pillar  401  with a size fitting for being inserted into a through hole  225  and an O-shaped protruding portion  403  correspondingly disposed in the O-shaped recess  2251 ; the supporting convex pillar  401  and the O-shaped protruding portion  403  are an integrated structure; wherein, the supporting convex pillar  401  is inserted into the through hole  225 , and the O-shaped protruding portion  403  is in the O-shaped recess  2251  and the protruding portion  4031  of the O-shaped protruding portion  403  is in contact with the spring element  42 ; apparently, the length of the supporting convex pillar  401  of the retainer  40  is larger than that of the protruding portion  4031  of the O-shaped protruding portion  403 . Additionally, the position of each retainer  40  corresponds to each second supporter  32  of the upper cover of outer container  12 . Furthermore, on a side of each retainer  40  on the outer surface of upper cover of inner container  223  of the upper cover of inner container  22 , a first fastener  44  that fastens the retainer  40  is respectively disposed, the first fastener  44  having a hole  441  with a size smaller than the retainer  40  so that part of the surface of the retainer  40  can be exposed; therefore, with the O-shaped recess  2251  and the first fastener  44  being joined together, the retainer  40  can be fastened and prevented from dropping down. Moreover, the first fastener  44  of the present invention is lock-fastened to the inner container  2  for storing the reticle with a screw and can also be disposed in the inner container  2  for storing the reticle either via being snap-fitted or adhered to the inner container  2 , the way of which is not limited in the present invention. And the material of retainer  40  is a wear-resistant polymer material so that friction that may generate particles and dusts which contaminate the reticle  9  in the inner container  2  can be prevented. 
         [0028]    Referring then to  FIG. 3 , which is a view of filter device of the upper cover of inner container of the present invention. As shown in  FIG. 3 , on the upper cover of inner container  22  of the reticle pod, a plurality of filtration holes  227  penetrating the upper cover of inner container  22  are disposed, and a filter material  50  is disposed on each of the filtration holes  227 . The filter material  50  of the present invention can be a porous filter membrane and can be selected from the group consisting of: glass-fiber filter, static electricity filter, electrically conductive filter membrane, PTFE filter, and porous ceramic material, which is not limited in the present invention. Moreover, a second retainer  52  can be further disposed on the filtration hole  227  to reinforce the fastening; the second retainer  52  can be lock-fastened to the inner container  2  via a screw or in other ways, the way of lock-fastening the second retainer  52  is not limited in the present invention. In a preferred embodiment of the present invention, two filtration holes form a set and the upper cover of inner container  22  is disposed with two sets of filtration holes  227 , and yet the actual number of filtration holes  227  disposed is not limited in the present invention. 
         [0029]    And then, referring to  FIG. 4 , which is a view of foolproof structure of the upper cover of inner container of the present invention. As shown in  FIG. 4 , an integrated foolproof structure  60  is respectively formed on four corners formed on the periphery  222  of the upper cover of inner container  22 . The characteristic is in that a portion of the foolproof structure  60  of the present invention will protrude from the periphery  222  of the upper cover of inner container  22 , and thus, when the upper cover of inner container  22  and the lower cover of inner container  20  are joined together, the protruding portion of the foolproof structure  60  will be snap-fitted on the periphery  22  of the lower cover of inner container  20 ; since the foolproof structure  60  is respectively formed on the four corners, when the inner container  2  is closed, the upper cover  22  and the lower cover  20  are successfully joined only when all the foolproof structures  60  on four corners are snap-fitted, the foolproof effect being thus achieved. Moreover, as the length and the width of the inner container  2  are not the same, the length-to-width ratio can also be taken into consideration when the inner container  2  is closed for determining whether the closing of inner container  2  is correctly performed. 
         [0030]    Referring then to  FIG. 5 , which is a view of the limiter of lower cover of inner container of the present invention. As shown in  FIG. 5 , each of the four corners of the first inner surface of inner container  201  of the lower cover of inner container  20  has a recess  204 , in which a limiter  70  is respectively disposed; the limiter  70  is a horizontal bar-shaped substrate  701  with two convex columns  703  disposed on two sides, and a bevel  704  is respectively formed at the open end of each of the convex columns  703 ; a supporting protruding point  705  is further disposed between the two convex columns  703  of the horizontal bar-shaped substrate  701 , and the supporting protruding point  705  and the two convex columns  703  are disposed on a straight line. When the limiter  70  is disposed in the recess  204  of the first inner surface of inner container  201 , the top surface of the horizontal bar-shaped substrate  701  of the limiter  70  and the first inner surface of inner container  201  will be on the same horizontal level. When the reticle  9  is to be placed onto the first inner surface of inner container  201 , if the reticle  9  shifts its position, the reticle  9  can be guided to the correct position by the bevels  704  of the convex columns  703  and each of the four corners of the reticle  9  is in contact with the supporting protruding point  705  on the horizontal bar-shaped substrate  701 ; the reticle  9  is thus placed onto the first inner surface of inner container  201 . 
         [0031]    Moreover, the pair of convex columns  703  on each limiter  70  can serve as identification devices on the robot to identify reference point for reticle alignment so that the robot can accurately grip the reticle. Furthermore, in addition to being disposed at four corners of the first inner surface  201  of the inner container  20 , each limiter  70  of the present invention can be alternatively disposed on the point of intersection at 146 mm on each side of the first inner surface  201  of the inner container  20 ; therefore, the position of each limiter  70  on the first inner surface  201  is not limited in the present invention as long as the position of each limiter  70  is on or beyond the point of intersection at 146 mm on each side of the first inner surface  201 , such design ensuring that the supporting protruding point  705  of each limiter  70  is only in contact with the edge of the reticle and does not cause wear of or damage to pattern on the reticle. 
         [0032]    Then, referring to  FIG. 6 , which is a view of the window of the lower cover of inner container of the present invention. As shown in  FIG. 6 , a plurality of windows  205  are disposed on the outer surface of lower cover of inner container  203  which is on the opposite side of the first inner surface of inner container  201  of the lower cover of inner container  20 , and a transparent substrate  80  made of transparent glass, transparent plastic material, or other materials is respectively disposed in each of the windows  205 ; on the transparent substrate  80 , a third fastener  82  is further disposed for snap-fitting the transparent substrate  80  to the window  205  and prevent the transparent substrate  80  from dropping down. The third fastener  82  is a frame-shaped member with a size fitting to the window, and thus the reticle inside can be monitored from outside the lower cover of inner container  20  via the window  205 . Therefore, during the process, there will be signals from platforms to inspect the process and function of a reticle via the window  205 . Moreover, a ring-shaped pad  84  is disposed between the transparent substrate  80  and the third fastener  82  and is made of polymer material such as PTFE; the primary objective of disposing the ring-shaped pad  84  is to isolate and thus prevent the transparent substrate  80  from contacting the third fastener  82  so that proper flexibility is allowed to protect the transparent substrate  80  from being damaged. Furthermore, after the third fastener  82  is disposed on the lower cover of inner container  20 , the third fastener  82  and the outer surface of lower cover of inner container  203  are at the same horizontal level, and thus the placement of the inner container  2  in the outer container  2  will not be hindered. The third fastener  82  of the present invention is lock-fastened onto the outer surface of lower cover of inner container  203  of lower cover of inner container  20  via a screw, and the way of lock-fastening is not limited in the present invention. 
         [0033]    Referring to  FIG. 7 , which is a sectional view of the reticle pod of the present invention. As shown in  FIG. 7 , the reticle  9  is first placed on the lower cover of inner container  20  of the inner container  2 , and, as described above, the four corners of the lower surface  91  of the reticle  9  will be first placed on the supporting protruding points  705  of the limiters  70  disposed on the four corners of the first inner surface of inner container  201 . The two columns  703  on two sides of each supporting protruding point  705  will be located right on the periphery  95  of the reticle  9  (namely, two sides of the right-angle corner). Thus, the two sides of each of the four right-angle corners of the reticle  9  will be respectively clamped by each convex column  703  and the reticle  9  can be prevented from shifting. In the following, facilitated by the guidance of the foolproof structure  60  of the upper cover of inner container  22 , the upper cover of inner container  22  is joined with the lower cover of inner container  20  in the designated direction and an inner container  2  for protecting the reticle  9  is thus formed. 
         [0034]    Then, the inner container  2  is placed onto the plurality of first supporters  30  of the lower cover of outer container  10  of the outer container  1 ; wherein, the first supporters  30  correspond to the positioning groove  207  of the outer surface of lower cover of inner container  203  of the lower cover of inner container  20  (referring to  FIG. 6 ), and therefore, the inner container  2  is guided by the positioning groove  207  to the correct position when being placed. The upper cover of outer container  12  is then closed; wherein, when the upper cover of outer container  12  is to be closed, each of the second supporters  32  on the upper cover of outer container  12  aligns with the retainer  40  in each of the through holes  225  of the upper cover of inner container  22 . When the upper cover of outer container  12  is closed, each second supporter  32  is driven by the closing action to exert a downward force and impose pressure on the exposed portion of the retainer  40  in the through hole  225 ; when the retainer  40  is pressed, the O-shaped protruding portion  403  will then impose pressure on the O-shaped spring element  42  in the O-shaped recess  2251 , and the retainer  40  will then press further down and inward (i.e. when the O-shaped spring element  42  is pressed, there is flexible space for the retainer  40  to press inward, and contrariwise, when the O-shaped spring element  42  is not pressed, its flexibility facilitates the retainer  40  to resume the original position); the supporting convex pillars  401  integrated with the O-shaped protruding portions  403  will also be pressed down and inward and will then be in contact with four corners of the upper surface  93  of the reticle  9 , in other words, when the upper cover of outer container  12  is closed, the supporting convex pillars  401  of the retainers  40  at four corners of the reticle  9  will press the four corners of the upper surface  93  of the reticle  9 , and therefore the reticle  9  can be stably fastened in the inner container  2  with the existent support from the supporting protruding points  705  of the four corners of the lower surface  91  of the reticle  9 ; the inner container  2  can also be stabilized with the second supporters  32  of the upper cover of outer container  12  pressing inward, and the security of the reticle  9  in the storing and transporting process is further ensured. 
         [0035]    Although the present invention has been described with reference to the aforementioned preferred embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims.