Abrasive-free polishing of hard disk substrate with H2O2-C4H10O2-Na2S2O5 slurry

摘要

The effect of tert -butyl hydroperoxide-sodium pyrosulfite ((CH~(3))~(3)COOH-Na~(2)S~(2)O~(5)) as an initiator system in H~(2)O~(2)-based slurry was investigated for the abrasive-free polishing (AFP) of a hard disk substrate. The polishing results show that the H~(2)O~(2)-C~(4)H~(10)O~(2)-Na~(2)S~(2)O~(5) slurry exhibits a material removal rate (MRR) that is nearly 5 times higher than that of the H~(2)O~(2) slurry in the AFP of the hard disk substrate. In addition, the surface polished by the slurry containing the initiator exhibits a lower surface roughness and has fewer nano-asperity peaks than that of the H~(2)O~(2) slurry. Further, we investigate the polishing mechanism of H~(2)O~(2)-C~(4)H~(10)O~(2)-Na~(2)S~(2)O~(5) slurry. Electron spin-resonance spectroscopy and auger electron spectrometer analyses show that the oxidizing ability of the H~(2)O~(2)-C~(4)H~(10)O~(2)-Na~(2)S~(2)O~(5) slurry is much greater than that of the H~(2)O~(2) slurry. The results of potentiodynamic polarization measurements show that the hard disk substrate in the H~(2)O~(2)-C~(4)H~(10)O~(2)-Na~(2)S~(2)O~(5) slurry can be rapidly etched, and electrochemical impedance spectroscopy analysis indicates that the oxide film of the hard disk substrate formed in the H~(2)O~(2)-C~(4)H~(10)O~(2)-Na~(2)S~(2)O~(5) slurry may be loose, and can be removed easily during polishing. The better oxidizing and etching ability of H~(2)O~(2)-C~(4)H~(10)O~(2)-Na~(2)S~(2)O~(5) slurry leads to a higher MRR in AFP for hard disk substrates.