Abstract:
A method is provided of manufacturing semiconductor devices formed on a semiconductor wafer, including placing the wafer in a semiconductor container and conveying the container to a semiconductor manufacturing apparatus. An opening of the container is opposed to an opening of the apparatus such that an opener of the apparatus holds a lid of the opening the container. A key of the opener is inserted to a latch groove of the lid, and the key is rotated to contact a latch of the lid. The openings are connected such that a velocity differential pressure ratio obtained by dividing the maximum velocity when the opener holding the lid horizontally moves away from the opening of the container, by the differential pressure between the inside pressure and the outside pressure of the apparatus, is set to be 0.06 ((m/s)/Pa) or less, and then the wafer is processed.

Description:
CROSS REFERENCE TO RELATED APPLICATION  
       [0001]     This application is a continuation application of application Ser. No. 11/391,640, filed Mar. 29, 2006, which, is a divisional application of application Ser. No. 10/974,819, filed Oct. 28, 2004 (now U.S. Pat. No. 7,048,493), which is a continuation application of application Ser. No. 10/031,785, filed Jan. 25, 2002, now abandoned, the disclosure of which is hereby incorporated by reference. 
     
    
     TECHNICAL FIELD OF THE INVENTION  
       [0002]     The present invention relates to a semiconductor container opening/closing apparatus, which opens and closes a lid of a semiconductor wafer container used in a semiconductor manufacturing process, and more particularly relates to a semiconductor device manufacturing method in which the semiconductor container opening/closing apparatus is installed in each semiconductor manufacturing apparatus and a semiconductor wafer is conveyed using the semiconductor wafer container.  
       BACKGROUND OF THE INVENTION  
       [0003]     Recently, in semiconductor manufacturing plants, semiconductor wafers are conveyed between each manufacturing apparatus while being stored in semiconductor containers (hereinafter, referred to as a container) with a lid that isolates the semiconductor wafers from the outer environment. The inside of the container is kept in a very clean condition in comparison to the outside and only a small number of foreign particles are adhered to the wafer inside the container if the lid of the container is not opened. The condition outside the container is the ISO cleanliness level 6 or the like, and if the wafer is left in such a condition, over time the foreign particles are adhered to a surface of the wafer. Consequently, the yield of a semiconductor component formed on the wafer is significantly decreased. The container opening/closing apparatus is provided in each manufacturing apparatus, and the inside of the manufacturing apparatus is kept in a very clean condition in comparison to the outside, that is, the ISO cleanliness level 1 to 2.  
         [0004]     When the wafer is conveyed from the container to the manufacturing apparatus or from the manufacturing apparatus to the container, the manufacturing apparatus and the container are first connected to each other via the container opening/closing apparatus. Next, the lid of the container is opened, and thereby it is possible to directly connect the clean area inside the manufacturing apparatus and the clean area inside the container. Therefore, there is little possibility that the wafer is exposed to the outside air.  
         [0005]     The velocity of opening the lid of the container in the conventional container opening/closing apparatus is set high in order to reduce the operating time. Also, the conventional container opening/closing apparatus is provided with a safety cover that covers a driving system in the rear side of the apparatus. As a result, the lower end portion of this safety cover has a closed structure.  
         [0006]     Conventional container opening/closing apparatuses have suffered from the following problem. That is, since the velocity of opening the lid of the container is high, the inside of the container is under negative pressure at the time of opening the lid of the container. As a result, foreign particles outside the container enter the container through the gap between the container and the container opening/closing apparatus, and the foreign particles adhere to the wafer.  
         [0007]     In addition, another problem also exists in the conventional container opening/closing apparatus. That is, since a safety cover is provided for the conventional container opening/closing apparatus to cover the driving system in the rear side thereof, and since the lower end portion of the safety cover has a closed structure, foreign particles are deposited inside the safety cover. These foreign particles are blown out when a lid elevator unit moves downward, and then enter the container to adhere to the wafer.  
         [0008]     An object of the present invention is to reduce the number of foreign particles adhering to a wafer by preventing the foreign particles from entering the container at the time of opening the container using the container opening/closing apparatus.  
         [0009]     Also, another object of the present invention is to reduce the number of foreign particles adhering to a wafer by preventing the foreign particles from being deposited inside the safety cover and preventing the foreign particles from being blown out.  
       DISCLOSURE OF THE INVENTION  
       [0010]     For the achievement of the above objects, the semiconductor container opening/closing apparatus and a method of opening and closing a lid of the semiconductor wafer container according to the present invention are characterized in that a velocity-differential pressure ratio obtained by dividing the maximum velocity (m/s) at the time of opening the semiconductor container, by the differential pressure (Pa) between the inside pressure and the outside pressure of the semiconductor manufacturing apparatus, is set to be 0.006 ((m/s)/Pa) or less.  
         [0011]     Also, the semiconductor container opening/closing apparatus according to the present invention is characterized in that an opening is provided at a lower end portion of the cover in the rear side of the semiconductor container opening/closing apparatus.  
         [0012]     Also, the semiconductor container opening/closing apparatus according to the present invention is characterized in that an exhaust fan is provided at a lower end portion of the cover in the rear side of the semiconductor container opening/closing apparatus. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]      FIG. 1  is a perspective view of a semiconductor container opening/closing apparatus according to a first embodiment of the present invention,  
         [0014]      FIG. 2  is a perspective view of a semiconductor container,  
         [0015]      FIG. 3  is a perspective view of a semiconductor manufacturing apparatus in which semiconductor container opening/closing apparatuses according to a first embodiment of the present invention are installed,  
         [0016]      FIG. 4  is a conceptual graph showing the correlation between the maximum velocity of opening the semiconductor container and the number of foreign particles adhering to a wafer,  
         [0017]      FIG. 5  is a conceptual view showing, relative to change of time, the velocity of opening the container by the semiconductor container opening/closing apparatus according to a first embodiment of the present invention,  
         [0018]      FIG. 6  is a conceptual graph showing, relative to change of time, the velocity of opening the container by the conventional semiconductor container opening/closing apparatus,  
         [0019]      FIG. 7  is a conceptual graph showing the correlation between the maximum velocity of opening the semiconductor container and the number of foreign particles adhering to a wafer, and  
         [0020]      FIG. 8  is a conceptual graph showing the correlation between the maximum velocity of opening the semiconductor container and the number of foreign particles adhering to the wafer. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0021]     For a more detailed description of a first embodiment of the present invention, the first embodiment will be described based on the accompanying drawings (FIGS.  1  to  8 ).  
         [0022]      FIG. 1  is a perspective view of a semiconductor container opening/closing apparatus (hereinafter, referred to as an opening/closing apparatus) according to the first embodiment of the present invention,  FIG. 2  is a perspective view of a semiconductor container (hereinafter, referred to as a container),  FIG. 3  is a perspective view of a semiconductor manufacturing apparatus (hereinafter, referred to as a manufacturing apparatus) in which the opening/closing apparatuses are installed,  FIGS. 4, 7 , and  8  are conceptual graphs each showing the correlation between the maximum velocity of opening the container and the number of foreign particles adhering to a wafer,  FIG. 5  is a conceptual graph showing, relative to change of time, the velocity of opening the container by the opening/closing apparatus according to the first embodiment of the present invention, and  FIG. 6  is a conceptual graph showing, relative to a change of time, the velocity of opening the container by the conventional opening/closing apparatus.  
         [0023]     Descriptions will be first made of respective structures of an opening/closing apparatus  100  and a container  200  by using  FIGS. 1 and 2 . The opening/closing apparatus  100  is mainly constituted by a stage  110  for placing the container  200 , and an opener  120  for holding a lid  220  of the container  200  and for opening and closing the lid  220 . The stage  110  is provided with positioning pins  112  for placing the container  200  in a proper position, and a slider  111  for bringing the container  200  closer to an opener  120 . In this embodiment, the slider  111  is movable back and forth by a motor and a ball screw (not shown) provided in the stage  110 . Rotating keys  121  are provided on the opener  120 , and the rotating keys  121  can rotate up to 90 degrees by a motor (not shown) provided in the opener  120 . In the rear side of the opener  120 , an opener opening/closing mechanism  130  for opening and closing the lid  220  of the container  200  by making the opener  120  move back and forth horizontally, and an opener elevator mechanism  131  for moving the opener  120  up and down are provided. Both of the opener opening/closing mechanism  130  and the opener elevator mechanism  131  are operated by a motor and a ball screw (not shown), and a safety cover  140  is provided on the whole of both driving units of the opener opening/closing mechanism  130  and the opener elevator mechanism  131  so that an operator(s) can not touch them easily.  
         [0024]     The container  200  is constituted by a container body  210  and the lid  220 . The container body  210  is provided with four latch grooves  211 , and a flange  212  is provided around the container body  210 . A shelf (not shown) is provided inside the container body  210  for storing wafers  300  horizontally, and twenty-five wafers can be stored therein. Key grooves  221  are provided on the lid  220  at positions corresponding to those of the rotating keys  121  of the opening/closing apparatus  100 . The rotating keys  121  of the opening/closing apparatus  100  are inserted into the key grooves  221  and rotated by 90 degrees. By virtue of this, four latches  222  in the lid  220  come in and out from the lid  220  by a cam mechanism (not shown) operating inside the lid  220 . The latches  222  are at positions corresponding to those of the latch grooves  211  of the container body  210 , and when the latches  222  come out from the periphery of the lid  220  while the lid  220  is inserted in the container body  210 , the lid  220  can be fixed to the container body  210 .  
         [0025]     The actual operation of opening the container  200  is carried out as follows. The container  200  is placed on the stage  110 . The slider  111  on the stage  110  is moved horizontally toward the manufacturing apparatus, and a surface of the lid  220  of the container  200  and the opener  120  of the opening/closing apparatus  100  are contacted to each other. At this time, though the flange  212  of the container  200  and a surface board  150  of the opening/closing apparatus  100  are partly contacted to each other, a gap is inevitably left therebetween due to the process accuracy of the container  200 . When the rotating keys  121  are rotated by 90 degrees in the clockwise direction toward the container  200  while the lid  220  and the opener  120  are contacted to each other, the key grooves  221  of the lid  220  are rotated and the lid  220  is fixed to the opener  120 . Simultaneously, the latches  222  are accommodated inside the lid  220  by a function of the cam mechanism (not shown) inside the lid  220 . Thereafter, the opener opening/closing mechanism  130  is horizontally moved toward the manufacturing apparatus to detach the lid  220  of the container  200  from the container body  210 . Specifically, the lid  220  of the semiconductor container  200  is held and opened in a direction vertical to an opening surface of the container  200 . Then, the opener  120  is moved downward by the opener elevator mechanism  131 .  
         [0026]     The operation of closing the container  200  is carried out in a reverse manner to the operation of opening the same, in which, after the opener elevator mechanism  131  is moved upward, the opener opening/closing mechanism  130  is moved horizontally toward the stage  110  to connect, to the container body  210 , the lid  220  fixed to the opener  120 . Thereafter, when the rotating keys  121  are rotated by 90 degrees in the counterclockwise direction, the latches  222  of the lid  220  are fit into the latch grooves  211  on the container body  210 . Thus, the lid  220  is fixed to the container body  210 . Finally, the slider  111  is moved horizontally in a direction opposite to the manufacturing apparatus, and, thereby, the container  200  is put into a state where it can be detached from the stage  110 .  
         [0027]      FIG. 3  shows an example where four opening/closing apparatuses  100  are mounted to a manufacturing apparatus  400 . Downflow is formed inside the manufacturing apparatus  400 , and the inside of the apparatus  400  is kept in the ISO cleanliness level 1 to 2, that is, the inside thereof is kept in a very clean condition in comparison to the outside of the manufacturing apparatus  400  which is in the ISO cleanliness level 6. If a wafer is left in the environment of the ISO cleanliness level 6, over time foreign particles adhere to a wafer surface. As a result, the yield of semiconductor components formed on the wafer is significantly decreased. The inside of the container  200  is shielded from the outside thereof, and if the wafer  300  is loaded and unloaded in the high-cleanliness environment, the cleanliness inside the container is maintained. Therefore, even if the container  200  is left in the environment of the ISO cleanliness level 6, only a small number of foreign particles adhere to the wafer  300  inside the container  200  unless the lid  220  of the container  200  is opened or closed.  
         [0028]     When the wafer  300  is moved from the container  200  to the manufacturing apparatus  400  or from the manufacturing apparatus  400  to the container  200 , the lid  220  of the container  200  is opened or closed after connection of the manufacturing apparatus  400  and the container  200  via the container opening/closing apparatus  100 . Thus, a clean area inside the manufacturing apparatus  400  and a clean area inside the container  200  are directly connected to each other. Since the pressure inside the manufacturing apparatus  400  is set to a slightly positive pressure in comparison to the outside thereof, there is little possibility that the foreign particles will flow through the gap between the flange  211  of the container  200  and the surface board  150  of the opening/closing apparatus  100 , except at the moment of opening or closing the container  200 .  
         [0029]     If the operating velocity of the opener opening/closing mechanism  130  of the opening/closing apparatus  100  is high, then the inside of the container  200  experiences a negative pressure at the time of pulling out the lid  220  from the container body  210 , and the foreign particles enter into the container  200  through the gap between the flange  211  of the container  200  and the surface board  150  of the opening/closing apparatus  100 , and adhere to the wafer  300 .  
         [0030]      FIG. 5  shows, relative to the change with time, the velocity of opening the container  200  by the opener opening/closing mechanism  130  of the opening/closing apparatus  100  according to the present invention. In  FIG. 5 , the horizontal axis represents time (s) and the vertical axis represents the velocity of opening (m/s), and the maximum velocity is 0.025 (m/s).  FIG. 6  shows, relative to the change with time, the velocity of opening the container  200  by the opener opening/closing mechanism  130  of the conventional opening/closing apparatus  100 . In  FIG. 6 , the horizontal axis represents time (s) and the vertical axis represents the velocity of opening (m/s), and the maximum velocity is 0.15 (m/s).  
         [0031]      FIG. 4  is a conceptual graph showing the correlation between the maximum velocity of opening the container and the number of foreign particles adhering to a wafer stored in the container when the inside pressure of the apparatus  400  is higher by 1 (Pa) than the pressure of the outside. In  FIG. 4 , the horizontal axis represents the maximum velocity (m/s) of opening the container by the opener opening/closing mechanism  130 , and the vertical axis represents the number of foreign particles (Number/WaferTimes) which have a grain size of 0.12 pm or more and which adhere to the uppermost wafer  300  stored in the container  200  per opening/closing of the container  200 .  FIG. 7  is a conceptual graph showing the correlation between the maximum velocity of opening and closing the container and the number of foreign particles adhering to a wafer when the inside pressure of the apparatus  400  is higher by 5 (Pa) than the pressure of the outside. The vertical and horizontal axes of  FIG. 7  represent the same variables as those of  FIG. 4 .  FIG. 8  shows a conceptual graph showing the correlation between the maximum velocity of opening and closing the container and the number of foreign particles adhered to a wafer when the inside pressure of the apparatus  400  is higher by 10 (Pa) than the pressure of the outside. The vertical and horizontal axes of  FIG. 8  represent the same variables as those of  FIGS. 4 and 7 .  
         [0032]     In  FIG. 4 , the number of foreign particles adhering to the wafer  300  exceeds 0.01 (Number/WaferTimes) at the maximum velocity of 0.06 (m/s), and it rapidly increases if the maximum velocity is over 0.06 (m/s). In  FIG. 7 , the number of foreign particles exceeds 0.01 (Number/WaferTimes) at the maximum velocity of 0.3 (m/s), and in  FIG. 8 , the number of foreign particles exceeds 0.01 (Number/WaferTimes) at the maximum velocity of 0.&amp; (m/s). As is apparent from  FIGS. 4, 7 , and  8 , it can be understood that the maximum velocity, at which the number of foreign particles increases, becomes higher in proportion to the differential pressure between the inside pressure and the outside pressure of the apparatus  400 .  
         [0033]     The number of foreign particles adhering to the wafer  300  can be reduced by decreasing the maximum velocity of opening of the container by the opener opening/closing mechanism  130 . However, the slow operating velocity in each unit of the opening/closing apparatus  100  influences the process faculty of the manufacturing apparatus  400  per unit time. Therefore, it is required to set the operating velocity in an appropriate range. For this reason, it is conceived that the operating velocity should be set in a certain range capable of—sufficiently assuring the operation ability of the semiconductor manufacture, and also be set lower than the operating velocity at which the number of foreign particles is 0.01 (Number/WaferTimes), which is a boundary at which the number of foreign particles adhering to the wafer begins to rapidly increase in all of  FIGS. 4, 7 , and  8 . Since the differential pressure between the inside pressure and the outside pressures of the apparatus  400  is proportional to the maximum velocity at which the number of foreign particles begins to increase, the number of foreign particles adhering to the wafer surface can be suppressed by setting a ratio (velocity-differential pressure ratio Dvp) between the Vmax: maximum velocity (m/s) of opening the container by the opener opening/closing mechanism  130  and APa: differential pressure (Pa) between the inside pressure of the apparatus  400  and the outside pressure so as to satisfy the formula I shown below: 
 
 V max/ A Pa= Dvp˜ 0.06, 
 
 where APa: differential pressure (Pa) between the inside pressure of the apparatus  400  and the outside pressure, Vmax: maximum velocity (m/s) of opening the container by the opener opening/closing mechanism  130 , and Dvp: velocity-differential pressure ratio (m/sPa). 
 
         [0034]     In this embodiment, since the velocity-differential pressure ratio is within the range defined by formula 1, the number of foreign particles adhering to the wafer  300  stored in the container  200  can be reduced. Therefore, the yield of the semiconductor component can be improved.  
         [0035]     Note that this embodiment is an example where the condition outside the container is in the ISO cleanliness level 6, and the number of foreign particles adhering to the wafer changes depending on changes in the surrounding condition. However, the maximum velocity at which the number of foreign particles adhering to the wafer begins to rapidly increase is always constant.  
         [0036]     By providing a packing at a contact position between a surface plate  150  of the opening/closing apparatus  100  and a flange  212  of the container  200 , and by filling the gap between the surface plate  150  and the flange  212 , the foreign particles which enter into the container at the time of opening the lid  220  of the container  200  are shut out. Thus, the number of foreign particles adhering to the wafer  300  can be reduced. If the packing is provided, however, the following problems are created. That is, one problem is that the packing itself generates dust due to the deterioration caused by the change with time and to repetitive use of the packing. Thus, there is an increase in the number of foreign particles adhering to the wafer. Another problem is that the cost is increased due to the additional cost required to provide the packing itself, to process the surface plate, and to install the packing. Since the packing is not required in this embodiment, the reliability is high and the cost is low.  
         [0037]     Also, in another embodiment (second embodiment) of the present invention, an opening is provided at a lower end portion of the safety cover  140  of the opening/closing apparatus  100 . In the conventional safety cover  140 , the opening is provided at only the upper end portion of the safety cover. Therefore, a problem has arisen that the foreign particles generated from the opener opening/closing mechanism  130 , the opener elevator mechanism  131 , or the like are deposited inside the safety cover  140 . As a result, the deposited foreign particles are blown out at the time when the opener elevator mechanism  131  moves downward, and enter the container  200  and adhere to the wafer. In this embodiment, since the opening is provided at the lower end portion of the safety cover  140 , the foreign particles are not deposited inside the safety cover and are not blown out. Therefore, the number of foreign particles adhering to the wafer  300  stored in the container  200  can be reduced, and thus the yield of the semiconductor component can be improved.  
         [0038]     The safety cover  140  covers the driving systems of the opener opening/closing mechanism  130  and the opener elevator mechanism  131  in order to ensure safety of an operator and to protect the driving systems at the time of conveying the opening/closing apparatus  100 . Therefore, even if the opening is provided at the lower end portion of the safety cover  140 , the safety cover does not lose its essential function.  
         [0039]     Also, in this embodiment, the opening is simply provided at the lower end portion of the safety cover  140 . However, the same effect can be expected by providing an exhaust fan at the lower end portion of the safety cover  140 .  
       INDUSTRIAL APPLICABILITY  
       [0040]     As described above, according to the present invention, it is possible to reduce the number of foreign particles entering into the container at the time of opening the container, and, therefore, the number of foreign particles adhering to the wafer can be reduced and the yield of the semiconductor component can be improved. In addition, since a packing is not required, an opening/closing apparatus having high reliability can be realized at low cost.  
         [0041]     Also, according to the present invention, since the foreign particles are not deposited inside the safety cover, the foreign particles are not blown out, and, thus, the number of foreign particles adhering to the wafer can be reduced. Therefore, the yield of the semiconductor component can be improved.