In-Situ Eis Approaches To The Aluminum Cmp Slurry Characterization

Electrochemical techniques including potentiodynamic scans and ac impedance measurements were applied to the study of the H3PO4-H2O2-based slurry of aluminum CMP. With the addition of H2O2, the corrosion potential increases about 600 mV, indicating that Al2O3 is formed and acts as a passivating layer. The anodic current density also increases with the addition of H2O2, indicating that the lower concentration of H2O2 produced a denser oxide layer. Four time-constants can be found for the non-abraded aluminum electrode in the slurry. Under abrasion, only the high frequency loops remain appreciable, so that the polishing mechanism was strongly associated with the properties of the barrier oxide layer. From the results of the ac impedance measurements. the polishing rate and growth rate of aluminum can be compared. In the presence of 1 vol.% H2O2, the polishing rate was almost equal to the growth rate of Al2O3, while in the presence of 3 vol.% H2O2 the polishing rate was slower than the growth rate. The results also showed that the addition of an appropriate amount of H2O2 not only increases the oxidation rate but also forms an oxide with looser structure, both of which promote the polishing rare of aluminum.