The effects of ultra-smooth surface atomic step morphology on CMP performances of sapphire and SiC wafers

Whether sapphire or SiC wafer, clear and regular atomic step morphology could be observed all over the ultra-smooth wafer surface via atomic force microscopy (AFM) using our CMP technology. However, towards sapphire and SiC wafers, the variations of atomic step widths and step directions on the whole of wafer surface are different. The step widths and step directions on the different positions of sapphire wafer are uniform, while that on SiC wafer are distinct. Thus, the effects of atomic step width on CMP removal rate of sapphire and SiC wafers were studied. On the other side, the CMP removal model of super-hard hexagonal crystalline wafer to realize atomically ultra-smooth surface is proposed. The variations of atomic step morphology towards different defects on sapphire and SiC wafers surface are analyzed, and the formation mechanism of the defects is discussed.