STABLE GOLD BUMP SOLDER CONNECTIONS

摘要

A metallic interconnect structure (200) for connecting a gold bump (205) and a copper pad (212), as used for example in semiconductor flip-chip assembly. A first region (207) of binary AuSn2 intermetallic is adjacent to the gold bump. A region (208) of binary AuSn4 intermetallic is adjacent to the first AuSn2 region. Then, a region (209) of binary gold-tin solid solution is adjacent to the AuSn4 region, and a second region (210) of binary AuSn2 intermetallic is adjacent to the solid solution region. The second AuSn2 region is adjacent to a nickel layer (213) (preferred thickness about 0.08 µm), which covers the copper pad. The nickel layer insures that the gold/tin intermetallic s and solutions remain substantially free of copper and thus avoid ternary compounds, providing stabilized gold bump/solder connections.