Etching characteristics of platinum in inductively coupled plasma using Cl2/CO

The effects of process parameters on etching properties were investigated for inductively coupled plasma etching of platinum with Cl2/CO mixed gas. The etch rates and selectivities of Pt against SiO2 depended significantly on the Cl2 concentration as the substrate temperature was raised. The volatile effect where the etch rates of Pt increase considerably above about 210 °C was not observed. The influence of O2 addition to a Cl2/CO gas mixture on the etch profile of patterned Pt films was evaluated. It was shown that the etch slope of patterned Pt was increased by enhancing the selectivity of Pt to the mask oxide. X-ray photoelectron spectroscopy and scanning electron microscope studies of the Pt surface etched partially with and without oxygen in a Cl2/CO gas mixture indicated that the etch slope may be increased by a reduction in the etch residues on Pt and by an enhancement in the selectivity of Pt against mask oxide. In the case of the addition of O2 at the substrate temperature lower than 120 °C, the fence polymer was observed at the patterned sidewall, but disappeared as the substrate temperature increased to 180 °C.