The effect of surface charge using amino acid and cationic surfactant for high material removal rate (MRR)

Ceria is used to polish the initial step height reduction due to its fast material removal rate (MRR) compared with other abrasives such as alumina and silica. The adhesion by electrostatic force occurs between the surface of ceria and silicon dioxide (SiO2), which is positive and negative, respectively. However, there is the limitation to raise the RR with only ceria suspension, which can be achieved by the addition of additives to the ceria suspension. In this work, we investigated the effect of surface charge using amino acid and cationic polymer as surfactants in ceria-based slurries on adsorption and oxide MRRs. To focus on the effect of surface charge, other conditions such as ceria size and shape are kept constant. Zeta potential experiments are conducted in the pH rage of 2-10 to understand the change of charged surface on ceria particles and SiO2 films. The more positively charged ceria implies the increased electrostatic force, which is the improved attraction and subsequent effect on RR. To identify the surfactants-adsorbed ceria, TGA measurements were analysed. Finally, the CMP procedures are performed using slurries containing amino acid and cationic surfactants to evaluate the effect of the MRR.