Nucleation and Growth of Copper on Ru-Based Substrates: Ⅰ. The Effect of the Inorganic Components

摘要

The effect of the inorganic components, namely copper sulfate (CuSO_4), sulfuric acid (H_2SO_4) and hydrochloric acid (HC1) on the nucleation and growth of copper on Ru-based substrate is reported in the absence and the presence of a suppressor molecule, polyethylene glycol (PEG). In the absence of PEG it was found that the island density, N_p was the highest when CuSO_4 and HC1 concentrations were low while H_2SO_4 concentration was high. The effect of each component remained similar when all components were mixed together. In the presence of PEG, the effect of CuSO_4 and H_2SO_4 remained similar. However, for the HC1, an optimal concentration was found where N_p reached a maximum value. The study illustrates the importance of an optimal bath composition toward faster coalescence of the Cu islands into a continuous Cu film for direct plating applications.