Mechanism Study of Fluoride Ion on the Effect of Silicon Polishing

The effect of fluoride ion (F^-) on the improvement of silicon removal rate for chemical mechanical polishing (CMP) is studied.The results showed the removal rate was increased from 0 to 57.7% with continuously adding KF into silica based slurry.To explore the mechanism, open circuit potential (OCP) and polarized plot were examined, which indicated the increasing was due to the passivation layer dissolution and the polarization current enhancement.The measurements showed when KF concentration reached 2.5% (wt), the polarization current was up to 44.5 μA/cm².Further tests of X-ray photoelectron spectroscopy and contact angle disclosed F ions could decrease silicon oxide production in alkaline slurry, raise the contact angle to 93.2°resulting in a strong hydrophobic surface.By reference of the atom removal model proposed by Pietsch, we analyzed silicon removal process using F ions alkaline slurry, which can provide an introduction to silicon slurry development with high removal rate.