Highly compliant plate for wafer bonding

Abstract

The present invention discloses a method that includes: providing two wafers; forming raised contacts on the two wafers; aligning the two wafers; bringing together the raised contacts; locally deflecting the two wafers; and bonding the raised contacts. The present invention also discloses a bonded-wafer structure that includes: a first wafer, the first wafer being locally deflected, the first wafer including a first raised contact; and a second wafer, the second wafer being locally deflected, the second wafer including a second raised contact, wherein the second raised contact is bonded to the first raised contact.

1 . A method comprising: 
 providing two wafers;    forming raised contacts on said two wafers;    reducing thickness of said two wafers;    pretreating a surface of said raised contacts;    aligning said two wafers;    bringing together said raised contacts;    locally deflecting said two wafers; and    bonding said raised contacts.    
   
   
       2 . The method of  claim 1  wherein said two wafers comprise partial wafers.  
   
   
       3 . The method of  claim 1  wherein said raised contacts are located on the faces of said two wafers.  
   
   
       4 . The method of  claim 1  wherein said locally deflecting of said two wafers is accomplished with a highly compliant plate.  
   
   
       5 . The method of  claim 4  wherein said highly compliant plate comprises a fluid to apply pressure to non-bonding sides of said wafers.  
   
   
       6 . The method of  claim 5  wherein said highly compliant plate further comprises a compliant barrier to separate said fluid from said non-bonding sides of said wafers, said compliant barrier comprising a flexible membrane.  
   
   
       7 . The method of  claim 5  wherein said fluid may be a gas.  
   
   
       8 . A method comprising: 
 providing a first wafer, said first wafer having a first raised contact;    stacking a second wafer over said first wafer, said second wafer and said first wafer being structurally and functionally dissimilar, said second wafer having a second raised contact, said second raised contact facing said first raised contact;    applying different pressure concurrently to said first wafer and said second wafer to locally deflect said first wafer and said second wafer; and    heating said first wafer and said second wafer to bond said first raised contact and said second raised contact.    
   
   
       9 . The method of  claim 8  wherein said first wafer and said second wafer comprise partial wafers.  
   
   
       10 . A method comprising: providing a first wafer having raised contacts located on a face and a second wafer having raised 
 contacts located on a back;    bringing together said face of said first wafer and said back of said second wafer;    partially bonding said two wafers face-to-back;    sealing edges of said two wafers; and    bonding raised contacts on said two wafers in a pressurized and heated chamber.    
   
   
       11 . The method of  claim 10  wherein said sealing of said edges is accomplished with copper sealing rings.  
   
   
       12 . The method of  claim 10  wherein said sealing of said edges is accomplished with an underfill.  
   
   
       13 . The method of  claim 10  wherein said two wafers comprise partial wafers.