Inductively coupled plasma etching of platinum with Cl-2/O-2/Ar gas chemistries was examined. Plasma characteristics were investigated with increasing O-2 ratios using a Langmuir probe and a quadrupole mass spectrometer. The chemical reaction during the platinum etching was also examined from the chemical binding states of the etched surface by X-ray photoelectron spectroscopy. Additional characterization employed a four-point probe, thin-film thickness measuring system, and scanning electron microscopy. The relationship between plasma characteristics and etch results with various O-2-gas mixing ratios was also studied. It was confirmed that small additions of oxygen into the Cl-2/Ar gas mixtures lead to high selectivity and a good sidewall profile without a fence, also referred to as a bull-ear.