Interfacial structures and electrical properties of HfO_2 gate dielectric

摘要

HfO_2 high-k dielectric films of 4nm and 5nm were both grown on Si substrate with the method of PEALD at 160°C. Both were treated with rapid thermal annealing (RTA) process at 500°C. High resolution transmission electron microscopy (HRTEM) indicated both films were not crystallized. X-ray photoelectron spectra (XPS) indicated that Hf-silicate was formed in the interfacial layer, and the valence-band offset (VBO) between the dielectric film and the substrate interface was calculated to be 3.5 eV. The electrical measurements indicated that the leakage current densities of the four and five nanometers' sample were 1.0mA/cm~2 and 0.8mA/cm~2 at gate bias of IV, and the equivalent oxide thicknesses of them were 0.9nm and 1.2nm respectively. Densities of interfacial states of them were calculated to be 1.58×10~(12)eV~(-1)cm~(-2) and 4.80×10~(11)eV~(-1)cm~(-2).