Tribological behavior of 6H–SiC wafers in different chemical mechanical polishing slurries

Abstract

The chemical mechanical polishing (CMP) slurry has a significant impact on the processing effects. However, the evaluation methods of processing effects, such as surface roughness, surface morphology and material removal rate (MRR), are affected by the instruments' accuracy and inspectors’ behaviors, which cannot reflect the change process of the wafer surface intuitively and accurately. This study evaluated the effect of different polishing slurries (H2O2, KMnO4 and Fenton reagent) on single crystal 6H–SiC in the form of friction and wear. Using a ball-on-disk tribotester, the friction and wear effects of these slurries on 6H–SiC were experimentally assessed, and then four polishing different slurries were employed for CMP experiments. The friction experiments showed that the SiC surface had obvious scratches and larger COF value only the silica sol abrasive existed. The SiC surface formed a loose and porous chemical reaction layer only the oxidant presented, which made the SiC surface rough and the COF curve fluctuate. When the chemical reaction worked in combination with the abrasive mechanical removal, the COF curve tended to stabilize but wear rate increased. The CMP experiments results were consistent with the friction test results.