| abstract |
The present invention relates to a method for forming a copper pillar on a semiconducting substrate, the copper pillar having an underbump metallization area comprising a metal less noble than copper and optionally a solder bump on the top portion, and having a layer of a second metal selected from tin, tin alloys, silver, and silver alloys deposited onto the side walls of said copper pillar. A layer of a first metal which is more noble than copper is deposited onto the entire outer surface of the copper pillar prior to deposition of the second metal layer. The layer of a second metal then has at least a reduced number of undesired pin-holes and serves as a protection layer for the underlying copper pillar. |