Use of chemical oxidizers with alumina slurry in Double Disk Magnetic Abrasive Finishing for improving surface finish of Si (100)

The present communication emphasizes on the polishing of monocrystalline silicon wafer Si (100) using Double Disk Magnetic Abrasive Finishing (DDMAF) under the influence of oxidizer i.e., Marshall's acid salt (K2S2O8,1%wt/wt), Caro's acid salt(KHSO5,1%wt/wt)) and Hydrogen peroxide (H2O2,0.05%wt/wt) mixed with 1200 mesh alumina slurry. The alumina slurry under the influence of these oxidizers for aforesaid weight percent was allowed to flow in the finishing gap ranging between (2-10) ml/min. The polishing with DDMAF was simultaneously executed at different polishing speeds and working gaps. A set of 20 experiments were planned using Response Surface Methodology (RSM) and surface roughness data of polished silicon wafers were recorded for each experimental trial. Analysis of Variance (ANOVA) was used to obtain the significant process parameters on the surface roughness. Statistical model for surface roughness in terms of process parameters was developed. The pooled model after neglecting the insignificant terms was optimized using fmincon for constrained non-linear minimization tool box available with MatLab13 software package. The optimization of the pooled surface roughness model could firmly determine the optimum polishing parameters for obtaining the desired minimum surface roughness. Confirmatory experiment was carried out at optimum polishing parameters and it was found that the theoretical results agreed well with the experimental findings. The work further focused into the study of surface integrity of unpolished Si (100) sample and the polished sample obtained at optimum parameter using SEM and AFM images.