| abstract |
A method is disclosed for depositing a copper seed layer onto a substrate surface, generally onto a barrier layer that is an alloy of a group VIII metal and a refractory metal. In one aspect, the alloy consists of at least 50% ruthenium and the balance a copper diffusion barrier material. A copper layer is electroplated on the alloy directly. In one aspect, the surface of the barrier layer is conditioned prior to plating to improve adhesion and reduce the critical current density for plating on the barrier layer. The conditioning may include cathodic pre-treatment or a plasma pre-treatment in a hydrogen or hydrogen/helium mixture. In one aspect, the substrate surface is immersed in an acidic plating bath and a nucleation waveform is applied to form a seed layer. In another aspect, the substrate is immersed in a neutral or alkaline copper solution that includes complexed copper ions. |