Effects of Surfactants on the Chemical Mechanical Polishing Performance of a-Plane Sapphire Substrates

The effects of four different types of surfactants, cetyltrimethylammonium bromide (CTAB, cationic type), sodium dodecyl benzene sulfonate (SDBS, anion type), N-Laurylaminoacetic acid (NL, amphoteric type) and primary alcohol ethoxylate (AEO, non-ionic type), on the chemical mechanical polishing (CMP) performance of a-plane sapphire substrates in the range of pH 6–12 were investigated using colloidal silica as abrasive particles. The results demonstrated that cationic surfactants promoted the material removal of the sapphire substrate in the range of pH 9–12, while anionic, amphoteric, and non-ionic surfactants inhibited the material removal of the sapphire substrate in the range of pH 6–10. The mechanism of material removal in sapphire CMP was discussed through AFM observations, zeta potential measurements, particle size distribution tests, and friction behavior analysis.