Ex parte MIYAZAWA et al. - Page 8

          Appeal No. 96-1805                                                          
          Application 08/200,432                                                      

               The Hoshi reference is directed to a method for bonding                
          semiconductor wafers in such a manner as to eliminate gas bubbles           
          between the two bonded surfaces.  The examiner focuses on the               
          embodiment illustrated in Figures 3A through 3F.  In this system,           
          first and second flat wafers 50A and 50B are pulled by vacuum               
          upon a pair of curved chucks 6A and 6B, whereupon they assume a             
          warped configuration (Figures 3A and 3B).  Each chuck is mounted            
          in a cover (22A and 22B) and, as shown in Figure 3C, the covers             
          are folded over upon one another to form a chamber having a gas             
          outlet 29.  There is no gas inlet.  At this point in the Hoshi              

          process, the warped wafers are held spaced from one another.  As            
          explained in column 4, chuck 6B then is raised to the position              
          shown in Figure 3D, in which the protruding center portions of              
          the wafers are placed in contact with each other (column 4, line            
          22).  The next step is to subject the interior of the chamber to            
          a vacuum greater than that which holds the wafers upon the                  
          chucks, whereupon they are released to flatten and make full                
          contact with one another, as shown in Figure 3E, so that they               
          bond together along their entire surfaces (column 4, lines 25               
          through 31).  This is intended to eliminate the presence of gas             
          bubbles between the bonded wafers.                                          


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