Sintered Metal Flip Chip Joints

Abstract

An integrated circuit die may be fabricating to have a plurality of contacts. A metal post may be formed on each of the plurality of contacts. A plurality of bumps may be formed on a plurality of contact regions of a leadframe or on the posts, in which the plurality of bumps are formed with a material that includes metal nanoparticles. The IC die may be attached to the leadframe by aligning the metal posts to the leadframe and sintering the metal nanoparticles in the plurality of bumps to form a sintered metal bond between each metal post and corresponding contact region of the leadframe.

What is claimed is: 
     
         1 . A method for fabricating an integrated circuit, the method comprising:
 fabricating an integrated circuit (IC) die having a plurality of contacts;   forming a metal post on each of the plurality of contacts;   forming a plurality of bumps on a plurality of contact regions of a leadframe or on the posts, in which the plurality of bumps are formed with a material that includes metal nanoparticles; and   attaching the IC die to the leadframe by aligning the metal posts to the leadframe and sintering the metal nanoparticles in the plurality of bumps to form a sintered metal bond between each metal post and corresponding contact region of the leadframe.   
     
     
         2 . The method of  claim 1 , in which the sintering the metal nanoparticles forms a sintered metal bond that is porous. 
     
     
         3 . The method of  claim 2 , in which the sintered metal bond has a porosity ranging from 0%-50%. 
     
     
         4 . The method of  claim 1 , in which a portion of the plurality of bumps is formed on a portion of the posts and another portion of the plurality of bumps is formed on a portion of the contact regions of the leadframe. 
     
     
         5 . The method of  claim 1 , in which forming the plurality of bumps is done by printing with an inkjet printer. 
     
     
         6 . The method of  claim 1 , in which forming a metal post is done by printing with an inkjet printer. 
     
     
         7 . The method of  claim 1 , in which sintering the metal nanoparticles is done by heating, by use of a Xenon flash tube, or by use of Formic acid. 
     
     
         8 . The method of  claim 1 , in which the metal nanoparticles include copper nanoparticles and silver nanoparticles. 
     
     
         9 . The method of  claim 1 , in which the metal nanoparticles include copper oxide nanoparticles. 
     
     
         10 . The method of  claim 1 , in which the metal nanoparticles include copper nanoparticles and graphite nanoparticles. 
     
     
         11 . An integrated circuit comprising:
 an integrated circuit (IC) die with a plurality of contacts, in which a metal post is formed on each of the plurality of contacts; and   a leadframe, in which a plurality of contact regions on the lead frame are aligned with the plurality of contacts and metal posts and coupled thereto by sintered metal bonds.   
     
     
         12 . The IC of  claim 11 , in which the sintered metal bonds are porous. 
     
     
         13 . The IC of  claim 12 , in which the sintered metal bond has a porosity ranging from 0%-50%. 
     
     
         14 . The IC of  claim 11 , in which the sintered metal bonds include copper nanoparticles and silver nanoparticles. 
     
     
         15 . The IC of  claim 11 , in which the sintered metal bonds include copper oxide nanoparticles. 
     
     
         16 . The IC of  claim 11 , in which the sintered metal bonds include copper nanoparticles and graphite nanoparticles. 
     
     
         17 . An integrated circuit leadframe comprising:
 a plurality of leads configured to couple to a plurality of contacts on an integrated circuit die; and   a plurality of bumps formed on the plurality of leads configured to align with the plurality of contacts on the integrated circuit die, in which the bumps are formed with a material that includes metal nanoparticles.   
     
     
         18 . The leadframe of  claim 17 , in which the leadframe is a multi-layer substrate. 
     
     
         19 . The leadframe of  claim 17 , in which the bumps have been sintered to form sintered metal bonds that are porous. 
     
     
         20 . The leadframe of  claim 17 , in which the metal nanoparticles include copper nanoparticles and silver nanoparticles; copper oxide nanoparticles; or copper nanoparticles and graphite nanoparticles.