Initial Cu Growth in Cu-Seeded and Ru-Lined Narrow Trenches for Supercritical Fluid Cu Chemical Deposition

The morphological stability of Cu films in narrow trenches during the initial growth of Cu was studied at temperatures of 140–280 °C for the chemical deposition of Cu in supercritical CO2. Cu seed layers agglomerated and the deposited Cu and the seed layer coalesced at elevated temperatures. This mechanism resulted in bottom-up like growth at lower temperatures of 160–180 °C. The seed agglomeration was suppressed by starting deposition before reaching the temperature at which agglomeration started of about 150 °C. When Ru-lined trenches were used instead of Cu-seeded trenches, no clear agglomeration or grain coarsening was observed and Cu grew with a conformal topography.