In the Damascene process, the need for separating plug and interconnect process steps is completely eliminated. This patterning scheme offers tremendous advantages, it will begin to emerge in the deep sub-micron generation and utilizes Al CMP as a critical part of the Al Damascene process. During Al CMP, the Al film surface reacts with slurry chemicals, resulting in passivation or dissolution reactions. Thus surface microstructure of Al films and slurry chemistry will determine the performance of metal CMP. Material characteristics of Al films have a great impact on its CMP behavior. Addition of Cu to Al generally increases the susceptibility to corrosion, thus leading to an increase in CMP removal rate. The grain size of Al film also affects its CMP performance. Films sputter-deposited at lower substrate temperature obtain higher removal rate due to increased grain boundary area and thus higher propensity to corrosion. In this study, AI-CMP characteristics are evaluated on Al alloy thin films of different compositions including : pure Al, Al-1.0% Si-0.5% Cu, Al-1% Cu, Al-0.5% Cu and Al-1% Si. Characteristics of the films such as alloy contents and grain size, and their effects on the CMP removal rates are investigated. The mechanism of Al CMP can be explained by the continuous formation and removal of a passivating layer formed on the Al surface during CMP. In this experiment, an Al2O3-based slurry is formulated with hydrogen peroxide added as the main oxidizer. CMP removal rates of Various Al thin films with alterations in slurry pH and oxidizer concentrations were monitored to assess the role of chemical erosion and mechanical abrasion.