Low-temperature crystallization of tantalum pentoxide films under elevated pressure

Ta2O5 thin films deposited via a metal-organic decomposition method were crystallized via atmospheric pressure annealing and a high-pressure crystallization (HPC) process. Ta2O5 thin films started to become crystallized at 700 °C as subjected to atmospheric pressure annealing. When the HPC process was adopted and annealing at 16.5 MPa was performed, the crystallization temperature of Ta2O5 films was greatly dropped to as low as 350 °C. The developed HPC process considerably reduced the thermal budget and energy consumption during film processing. The crystallized Ta2O5 phase was found to be homogeneously distributed within the HPC-derived films. With annealing at 700 °C under atmospheric pressure, the silicon species diffused from the substrates into the Ta2O5 layers, thereby leading to reduced dielectric constants. The HPC process effectively suppressed the interdiffusion between the substrates and dielectric layers by lowering the required heating temperature, and also significantly increased the dielectric constants of Ta2O5 thin films. The HPC process was confirmed to effectively lower the crystallization temperature and improve the dielectric properties of Ta2O5 thin films.