Influence of Abrasive on CMP Quality for NiP Substrate of Computer Hard-Disk

As the main unit of data storage of the computer, the hard-disk storage density is increasing continuously, which is influenced directly by surface quality, so the substrate surface must be smooth and no-defect. Currently, the chemical mechanical polishing (CMP) technology with nanometer abrasive is adopted as the precise disc polishing. In this paper, the chemical character of NiP substrate of computer disk was analyzed, the CMP mechanism was discussed. The CMP experiments were performed with alkali slurry. The action of abrasive on NiP film CMP was analyzed. It was indicated that the abrasive in slurry not only has the effect of grinding but also acts as micro-stirrer during CMP process. According to the experiments the effect of silica sol size and concentration in alkali slurry on removal rate and roughness of NiP substrate were analyzed and the higher removal rate was obtained. Low roughness was realized with small size and low hardness silica sol as abrasive.