Chemical Mechanical Polishing Optimization for 4H-Sic

Scratch free surfaces are required for substrates used in epitaxial growth. Silicon carbide (SiC) is a substrate material that is used in the epitaxial growth of SiC, GaN, and InGaN electronic devices. Preliminary chemical mechanical polishing (CMP) studies of 1 3/8" 4H-SiC wafers were performed in an attempt to identify the polishing parameter values that result in a maximum material removal rate and thus reduce substrate polishing time. Previous studies reported increased material removal rates associated with increasing polishing temperature, slurry pH, pressure, and polishing pad speed. In the current study, the effects of temperature, slurry pH, polishing pressure, and polishing pad speed were examined independently while keeping other polishing parameters constant. Material removal rates were determined using pre and post-polish wafer mass measurements. Photographs at specific wafer locations were obtained before and after each polishing period and compared to calculated removal rates.