Ultrasonic vibration assisted double disc chemo-magnetorheological finishing of silicon wafer: Experimental investigations and optimization for surface roughness

Abstract

To polish the surface of silicon wafers, the impact of ultrasonic vibration assistance on the double disc chemo-magnetorheological finishing was investigated. The in-house setup was fabricated to provide vibrations to the workpiece during the polishing in the longitudinal direction. The central composite design (CCD) approach was adopted in experiment planning to understand the influence of process parameters (like magnets rotation, abrasive concentration, and ultrasonic power) on the surface roughness ([Formula: see text]). A 3D optical profilometer was employed to check the surface roughness of the polished wafers. The individual and interaction of significant process factors affecting were determined using the analysis of variance (ANOVA) technique. A regression equation based on response surface methodology was developed. The process parameters were optimized using a genetic algorithm to maximize the change in surface roughness before and after polishing. The experiment performed at an optimized set resulted in an average surface finish of 3.4 nm. A 3D surface plots and scanning electron microscopy (SEM) were used to understand the changes on the surfaces of unpolished and polished samples at the optimized parameters.