Toward Low-Thermal-Budget Processing in Ferroelectric Hf0.5Zr0.5O2 Thin Films by Ozone Interface Oxidation

Low-thermal-budget processing is strongly required to implement ferroelectric Hf0.5Zr0.5O2 (HZO) thin films to the back end of line (BEOL) of CMOS technologies. In this work, the O-3 oxidation approach is used to form an interface oxidation layer between TiN and the following deposited HZO, achieving robust ferroelectricity under extremely low annealing temperatures. It is shown that, after rapid thermal annealing (RTA) at 350 degrees C (300 degrees C), the maximum double remanent polarization (2P(r)) could reach 42.6 mu C/cm(2)(13.3 mu C/cm(2)) with more than 10(8) field-cycling endurance. The formation of the TiO2 layer at the interface of HZO/TiN supplies greater tensile stress, which is responsible for the low-RTA-temperature ferroelectricity with an optimum oxidation time of 40s. The proposed TiN surface oxidation method facilitates the BEOL compatibility and provides feasible avenues to high-performance ferroelectric HZO thin films.