Ultrathin CVD barrier/seed for 0.1 /spl mu/m dual damascene Cu interconnects

Cu films grown using metalorganic chemical vapor deposition were investigated as a function of barrier material. In particular, the minimum thickness (t _crit) at which the copper film became continuous in a high aspect ratio feature was determined to depend strongly on the underlying barrier material and properties. When the CVD Cu film was deposited directly on the barrier material, the t _crit was >200 Å, whereas with the addition of a more conductive nucleation layer a t _crit as low as 100 Å was achieved. The correlation of t _crit to microstructural and mechanical properties was also investigated.