Relationships between etch rate and roughness of plasma etched surface

Relationships between etch rate and surface roughness are examined as a function of process factors, including source power, bias power, pressure, and O₂ fraction. Experimental factor ranges are 600-900 W source power, 50-150-W bias power, 4-16-mtorr pressure, and 0%-80%-O₂ fraction. Atomic force microscopy was used to quantify surface roughness of silicon carbide etched in a C₂F₆ inductively coupled plasma. The impact of ion energy was estimated by means of DC bias. The etch rate was inversely related to surface roughness as source power (plasma density) varied. The source power-induced DC bias was strongly correlated to surface roughness. For variations in bias power (ion bombardment energy), the etch rate was almost linearly correlated to both surface roughness and DC bias. For variations in pressure or O₂ fraction, the etch rate was related to surface roughness in a complex way.