Relationship between Concentration, Time and Surface Roughness of GaAs Wafer in Lapping Process: An Experimental Investigation

Surface roughness and lapping time are important factors to evaluate the lapping results at micron-scale. These factors can be affected by concentration of lapping slurry. In this paper, the relationship between concentration of lapping slurry, lapping time and surface roughness of GaAs wafer was investigated. A mixture of SiC powder and DI water was selected as lapping slurry. An experimental investigation was described, including the effects of three mentioned parameters in each other. Surface roughness and lapping time were selected as two main factors determining the best concentration of slurry in lapping process on GaAs wafer. The lapping process was carried out using ZYP280 Lapping & Polishing machine while the wafer thickness was characterized using JCH-based Digital Precision Thickness Gauge. The Surface topography and roughness were calculated from the AFM images using an AFM software program. The obtained results showed that the best concentration for a desired roughness is 20%SiC in lapping slurry.