High Pressure Microwave Annealing Effect on Electrical Properties of Hf<sub><i>x</i></sub>Zr<sub>1–<i>x</i></sub>O Films near Morphotropic Phase Boundary
Minhyun Jung, Chaeheon Kim, Junghyeon Hwang, Giuk Kim, Hunbeom Shin, V. Gaddam, Sanghun Jeon
Abstract
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 °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 (∼40) at the near morphotropic phase boundary for a Zr-rich hafnia (Hf 0.25 Zr 0.75 O 2 ) capacitor at a relatively low temperature (350 °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.