Inductively coupled plasma reactive ion etching of Pd thin films with TiN hard masks was carried out in a CH3COOH/Ar gas mixture. The addition of CH3COOH to Ar gas decreased the etch rate but a good etch profile with a high degree of anisotropy was obtained at 50% CH3COOH/Ar. Variations in the etch parameters showed that high inductively coupled plasma power and dc-bias voltage improved the etch profile. X-ray photoelectron spectroscopy and optical emission spectroscopy results revealed that the Pd films in CH3COOH/Ar gas followed the sputtering etch mechanism assisted by the oxidation and sidewall protection provided by polymer films. (C) 2017 Elsevier B.V. All rights reserved.