The addition of surfactant to slurry for polymer CMP: Effects on polymer surface, removal rate and underlying Cu

Polymers have been considered for interlevel dielectric (ILD) applications in a multilevel metallization scheme mainly because of their low dielectric constant and their low intrinsic stress. As ILDs, polymers may be subjected to chemical mechanical polishing (CMP) to achieve global planarization. This study investigates both the effect of surfactant addition to the slurry on the polymer removal rate and surface condition and the effect on the slurry of polishing Cu and Al. The addition of a small amount of surfactant increases the polymer removal rate from nearly 0 to 100 nm min(-1) using 0.06 mu m alumina abrasive, even though very low abrasive concentrations (0.1%) were used to reduce the scratching of the polymer surface during CMP. Removal rates of Cu and Al were less than 12 nm min(-1), and the Cu was not scratched while the softer Al film was severely scratched.