The Role of Alanine in the Chemical Mechanical Polishing of Aluminum

With the evolution of integrated circuits, the transition from polycrystalline silicon to aluminum as the gate electrode has become prevalent due to its inherent advantages. This study delves into the impact of pH and alanine on the aluminum removal rate and surface roughness during chemical mechanical polishing (CMP) using colloidal silica as the abrasive. Alanine is incorporated as a complexing agent in the polishing slurry under acidic environment. The mechanistic role of alanine in the aluminum CMP process was explored using techniques such as electrochemical tests, scanning electron microscope, X-ray photoelectron spectroscopy, and UV–visible spectroscopy. Furthermore, density functional theory calculations were employed to investigate the quantum chemical parameters of alanine and further explore its complexation mechanism. The experimental results indicate that at an alanine concentration of 1.5 wt%, the Al removal rate reaches 2124.07 Å min-1 with a surface roughness is 1.33 nm. The interaction between alanine and aluminum ions (Al3+) yields soluble Al-alanine complexes, which facilitate the corrosive process on the surface of Al and enhance its removal rate.