[en] Plasma etching of HfO₂ at an elevated temperature is investigated in chlorine-based plasmas. Thermodynamic studies are performed in order to determine the most appropriate plasma chemistry. The theoretical calculations show that chlorocarbon gas chemistries (such as CCl₄ or Cl₂-CO) can result in the chemical etching of HfO₂ in the 425-625 K temperature range by forming volatile effluents such as HfCl₄ and CO₂. The etching of HfO₂ is first studied on blanket wafers in a high density Cl₂-CO plasma under low ion energy bombardment conditions (no bias power). Etch rates are presented and discussed with respect to the plasma parameters. The evolution of the etch rate as function of temperature follows an Arrhenius law indicating that the etching comes from chemical reactions. The etch rate of HfO₂ is about 110 A /min at a temperature of 525 K with a selectivity towards SiO₂ of 15. x-ray photoelectron spectroscopy analyses (XPS) reveal that neither carbon nor chlorine is detected on the HfO₂ surface, whereas a chlorine-rich carbon layer is formed on top of the SiO₂ surface leading to the selectivity between HfO₂ and SiO₂. A drift of the HfO₂ etch process is observed according to the chamber walls conditioning due to chlorine-rich carbon coatings formed on the chamber walls in a Cl₂-CO plasma. To get a very reproducible HfO₂ etch process, the best conditioning strategy consists in cleaning the chamber walls with an O₂ plasma between each wafer. The etching of HfO₂ is also performed on patterned wafers using a conventional polysilicon gate. The first result show a slight HfO₂ foot at the bottom of the gate and the presence of hafnium oxide-based residues in the active areas