Seed layer corrosion of damascene structures in copper sulfonate electrolytes

The influence of sulfonic acid concentrations in copper methanesulfonate, Cu(CH3SO3)2:CH3SO3H, plating solutions on the stability of a 1000 Å seed layer in Damascene structures is presented. Immersion of a seeded wafer into the plating solutions shows little tendency to corrode up to 3600 s. Anodic current density steps initiate seed layer corrosion resulting in exposure of the underlying TaN barrier layer. Large current density steps (>300 μA cm−2) or high free methanesulfonic acid concentration causes a slightly more rapid dissolution of the seed layer. The anodic dissolution efficiency is greater than 100% indicating chemical dissolution of copper is slow leading to a stable seed layer in these media.