Surface Activation by Electrolytically Ionized Slurry during Cu CMP

Abstract

In semiconductor chip fabrication, flatness of the layer is vital, and is achieved by chemical mechanical planarization (CMP). Slurry determines mechanisms for removal, and therefore accounts for the most expense in CMP. However, conventional slurry supply systems lead to wastage of the slurry not used in polishing. Therefore, this study proposes a new slurry supply method using ionization of slurry by electrolysis. Applying an electric force to the slurry may significantly reduce slurry consumption in the CMP process. First, stainless steel was selected as a suitable electrode for the system through a simple experiment. With this system, the material removal rate was evaluated according to the applied voltage and compared to that in the conventional method under different slurry flow rates. The removal mechanism of the ionized slurry was investigated by UV-visible spectroscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy. The band intensities of the intramolecular bonding structures and amounts of oxygen and Cu oxide on the surface were different depending on the electrolysis in the slurry. Accordingly, the effect of the ion-rich slurry was verified. This method is promising for efficient slurry supply systems in CMP applications as well as other manufacturing processes.