High Pressure Microwave Annealing Effect on Electrical Properties of Hf x Zr1-x O Films near Morphotropic Phase Boundary

In this paper, we report for the first time the effect of high-pressure microwave annealing (HPMWA) on the electrical properties of hafnium zirconium oxide capacitors. The high-pressure annealing technique has been utilized to increase ferroelectricity in hafnia and is very effective for curing the defect in the film and at the interface. However, it still requires a relatively high process temperature of >450 degrees C. This is not compatible with the process for use in an oxide semiconductor-based ferroelectric thin film transistor (TFT). Thus, we need to develop a process for achieving high ferroelectricity and lowering the defect in hafnia even at relatively low temperatures. Here, HPMWA was effective in obtaining a high dielectric constant (similar to 40) at the near morphotropic phase boundary for a Zr-rich hafnia (Hf0.25Zr0.75O2) capacitor at a relatively low temperature (350 degrees C) and high pressure (50 bar) and improving its electrical characteristics. Also, the 15-nm-thick hafnia capacitor annealed by HPMWA exhibits low leakage current (2.5 nA @ 4.5 V) and a fast-median nucleation speed (63 ns) in the nucleation-limited switching model compared to the conventional annealing process. We expect this to be used for core processes for low-temperature and 3D ferroelectric applications.