The Effect of Hydrogen Peroxide on Frictional and Thermal Behaviors in a Citric Acid-Based Copper Chemical Mechanical Planarization Slurry

摘要

The effect of H_2O_2 on the frictional and thermal behaviors of a citric acid-based slurry was characterized during Cu polishing. As the H_2O_2 concentration increased, the static and dynamic etching rates gradually decreased. The removal rate of Cu initially increased and reached the maximum value at a slurry concentration of 5 vol % H_2O_2 after which the removal rate gradually decreased with further increases in H_2O_2 due to the formation of a thick Cu oxide layer. The frictional force gradually decreased with increased H_2O_2 concentration. The friction force was high in spite of the low removal rate in the 1 vol % H_2O_2 slurry. The pad temperature changed as a function of H_2O_2 concentration in a manner similar to at that of the friction force. The higher pad temperature resulted in higher static etching and corrosion rates of Cu during polishing.