We fabricated TaN-gate electrodes on HfO2 and SiO2 films by wet etching using NH4OH/H2O2 solution and investigated the electrical and structural properties of the TaN/SiO2 and TaN/HfO2 interfacial layers. The effective work function (Φm,eff) of TaN on SiO2 and HfO2 are 4.4 and 4.6 eV, respectively. The Φm,eff on SiO2 remained constant after post-metallization anneal (PMA) at temperatures of up to 750 °C and increased after 900 °C, but the Φm,eff on HfO2 increased after PMA at 750 °C. The analysis by X-ray photoelectron spectroscopy (XPS) indicated that Ta oxide was formed near the TaN/SiO2 and TaN/HfO2 interfacial layers after the annealing at 900 °C. It was concluded that the Φm,eff instability is strongly associated with the Ta-O bond formation at the interfaces.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Surfaces and Interfaces
- Surfaces, Coatings and Films
- Metals and Alloys
- Materials Chemistry