Inductively Coupled Plasma Etching of Chemical-vapor-deposited Amorphous Carbon in N2/H2/Ar Chemistries

In this study, we investigated the etching characteristics and the mechanism of an amorphous carbon (a-C) layer for a multi-level resist (MLR) structure. CVD (chemical-vapor-deposited) a-C layers with a SiO2 hard-mask were etched in an ICP (inductively coupled plasma) etcher while varying the process parameters, such as the top electrode power, the bottom electrode power, and the gas flow ratio in the N-2/H-2/Ar plasma. The results indicated that the etch rate and the profile angle of the CVD a-C increased with increasing H-2 gas flow ratio in the N-2/H-2/Ar plasma. As the H-2 flow ratio increased, the etch rate and the profile angle increase, due to the increased formation of H radicals in the plasma, leading to enhanced chemical reactions with carbon atoms. Also, the etch rate of the CVD a-C increased with increasing top and bottom electrode powers.