Ferroelectric YMnO@sub 3@ thin films are excellent dielectric materials for high integrated ferroelectric random access memory (FRAM). YMnO@sub 3@ thin films have one polarization axis (c-axis), contain heavy and hard-deoxidizing elements, and do not contain volatile elements such as Bi and Pb, which easily diffuse into the Si substrate and lead to point defects. In this study, YMnO@sub 3@ thin films were etched with a CF@sub 4@/Cl@sub 2@/Ar gas combination in inductively coupled plasma (ICP). Etching characteristics on ferroelectric YMnO@sub 3@ thin films have been investigated in terms of etch rate and selectivity. The CF@sub 4@/(CF@sub 4@+Ar) was fixed at 0.2, and the YMnO@sub 3@ thin films were etched by adding Cl@sub 2@. Etching properties of YMnO@sub 3@ were measured according to the various etching parameters such as the rf power, dc-bias voltage, chamber pressure, and gas mixing ratio. The chemical reaction in the surface of the etched YMnO@sub 3@ films was investigated with x-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS). For the diagnosis of the CF@sub 4@/Cl@sub 2@/Ar plasma, optical emission spectroscopy (OES) and Langmuir probe were used. The etch profile and surface residues of etched YMnO@sub 3@ thin films was investigated by scanning electron microscopy (SEM). @FootnoteText@ Acknowledgement; University Research Program supported by Ministry of Information and Communication in South Korea.