Method of stacking wafers with anisotropic conductive adhesive

Abstract

The present invention includes a method that provides a first wafer; forms a first raised contact from a first plug on the first wafer; provides a second wafer; forms a second raised contact from a second plug on the second wafer; applies an anisotropic conductive adhesive over the first wafer; aligns the second wafer to the first wafer; attaches the second wafer to the anisotropic conductive adhesive to form a continuous and conductive path between the first raised contact and the second raised contact. The present invention also includes a structure that has an anisotropic conductive film, the anisotropic conductive film has a front surface and a rear surface; a first raised contact is located over the front surface, the first raised contact forming part of a first wafer; and a second raised contact located over the rear surface, the second raised contact forming part of a second wafer, where the second raised contact faces the first raised contact.

1 . A method comprising: 
 providing a first wafer;    forming a first raised contact from a first plug on said first wafer;    providing a second wafer;    forming a second raised contact from a second plug on said second wafer;    applying an anisotropic conductive adhesive over said first wafer;    aligning said second wafer to said first wafer;    attaching said second wafer to said anisotropic conductive adhesive to form a continuous and conductive path between said first raised contact and said second raised contact.    
     
     
         2 . The method of  claim 1  wherein said anisotropic conductive adhesive is applied as a paste.  
     
     
         3 . The method of  claim 1  wherein said anisotropic conductive adhesive is applied as a film.  
     
     
         4 . The method of  claim 1  wherein said anisotropic conductive adhesive comprises a binder and a filler.  
     
     
         5 . The method of  claim 4  wherein said binder comprises a thermoset.  
     
     
         6 . The method of  claim 4  wherein said filler comprises spherical conductive particles.  
     
     
         7 . A method comprising: 
 providing a first wafer, said first wafer having a first raised contact;    forming an anisotropic conductive film over said first wafer, said anisotropic conductive film comprising a binder and a filler;    stacking a second wafer over said anisotropic conductive film, said second wafer having a second raised contact, said second raised contact facing said first raised contact; and    applying pressure and heat to cure said binder and to trap a portion of said filler between said first raised contact and said second raised contact, said portion becoming a continuous and conductive path.    
     
     
         8 . The method of  claim 7  wherein said first wafer and said second wafer are structurally similar.  
     
     
         9 . The method of  claim 7  wherein said first wafer and said second wafer are functionally similar.  
     
     
         10 . The method of  claim 7  wherein said binder serves as an underfill between said first wafer and said second wafer.  
     
     
         11 - 15 . (canceled)