Effects of chemical mechanical polishing (CMP) parameters on NIP/AL substrate surface characteristics

Abstract

Chemical Mechanical Polishing (CMP) process is widely used for global planarization of substrate and wafer technology. The purpose of the CMP is to ensure wide planarization, uniformity, precise surface finish and non-defective surface. CMP has been used in the Hard Disk Drive industry as a final process at the substrate level to provide super fine finish of the substrate surface. With the tremendous demand for increased substrate storage capacity over the years, the Head Media Spacing (HMS) between substrate and slider become more stringent. It is desirable to achieve lower HMS in order to enable good writeablity and strong read back signal integrity and thus will improve the reliability of the slider inside the HDD. The reduction on HMS will lead to more stringent substrate surface finish requirement. Since there is no defined mathematical model of current in heritage process for Johor Bahru Substrate Plant A, this study will investigate effects of the CMP parameters on the NiP/Al substrate by using Design of Experiment (DOE) approach. A better understanding of the interaction behavior between various parameters and the effect on the material removal rate, substrate roughness and waviness is achieved by using statistical analysis technique. Mathematical model were derived and optimal solution is proposed to further improve the process.