Surface roughness of silicon carbide etching in a NF3 inductively coupled plasma

Silicon carbide was etched in a NF3/CH4 inductively coupled plasma. Surface roughness measured by atomic force microscopy was investigated as a function of process parameters. Both etch rate and dc bias were correlated to the surface roughness. To optimize the surface roughness, a 24 full factorial experiment was conducted for 700-900 W source power, 50-150 W bias power, 0.80-1.60 Pa, and 20-100% NF3 percentage. Main effect analysis revealed that the surface roughness is the most strongly affected by the bias power. For variations in the bias power or NF3 percentage, decrease in the surface roughness was observed only as positive variations in the etch rate and dc bias are considerably large. The surface roughness with the pressure was chemically dominated as illustrated by its inverse relationship with the dc bias. For the variations in the NF3 percentage, the radical variation was estimated to play a more dominant role. The smoothest surface roughness of 0.312 nm was obtained at 700 W source power, 150 W bias power, 1.60 Pa pressure, and 100% NF3 percentage.