INTERCONNECTIONS FOR FLIP-CHIP USING LEAD-FREE SOLDERS AND HAVING REACTION BARRIER LAYERS

摘要

An interconnection structure suitable for flip-chip attachment of microelectronic device chips to packages, comprising a two, three or four layer ball-limiting composition including an adhesion/reaction barrier layer, and having a solder wettable layer reactive with components of a tin-containing lead free solder, so that the solderable layer can be totally consumed during soldering, but a barrier layer remains after being placed in contact with the lead free solder during soldering. One or more lead-free solder balls is selectively situated on the solder wetting layer, the lead-free solder balls comprising tin as a predominant component and one or more alloying components. With a two-layer ball-limiting composition comprising an adhesion/reaction barrier layer, wherein the adhesion/reaction barrier layer serves both as an adhesion layer and a reaction barrier layer, the adhesion/reaction barrier layer can be comprised of a material selected from the group consisting of Zr and ZrN