Effect of Process Parameters on Polishing Performance of Pure Lead During Chemical Mechanical Polishing

In order to obtain high-quality pure lead surface, based on self-made polishing slurries, the influence of shape, particle size and concentration of colloidal silica polishing particles, as well as down force, the rotation speed and direction of polishing head / disc and the slurry flow rate on the surface material removal rate and roughness of lead sheet were investigated by chemical mechanical polishing (CMP). The results revealed that, compared with the larger spherical colloidal silica polishing particles, the smaller particle with brow-shaped were more beneficial to the polishing of lead sheet. The influence of particle size and concentration of polishing particles on the polishing performance of pure lead mainly depended on the coupling relationship among lead sheet surface, colloidal silica particles and the lint on polishing pad surface. With the change of down force, the rotation speed and direction of polishing head / disc as well as the slurry flow rate, the thickness and status of polishing slurries varied at the lead sheet / polishing pad interface, which directly affected the fluidity, lubricity and dispersion of polishing slurries and the chemical-mechanical interaction between polishing particles, chemical reagent and lead sheet surface, thereby affecting the polishing quality and the material removal rate. By the investigation of the influence of process parameters and parameters optimization, this work finally obtained an ideal ultra-smooth pure lead surface with surface roughness of R_a 1.5 nm and the material removal rate of 380 Å/min.