SURFACE AND INTERFACE INVESTIGATION OF NANOMETRIC DIELECTRIC FILMS ON SiAND ON SiC

Dielectric films on Si or SiC were investigated using angle-resolved X-ray photoelectron spectroscopy (ARXPS) and ion beam analysis techniques, namely high and low energy ion scattering (RBS and LEIS) and narrow nuclear resonance profiling (NRP) combined with isotopic substitution. For the Si substrate, attention was focused on the thermal stability of materials candidate to replacingSiO2in Si-based microelectronic devices (so-called "high-kdielectrics"):Al2O3,ZrSixOy,ZrAlxOy,HfSixOy, andGdSixOy. Mobility of different atomic species — especially Si and O — was observed at both the surface of the films and the interface with Si. Such atomic transport may have serious consequences concerning application of these materials in the microelectronics industry. For the SiC substrate, attention was focused on the initial stages of thermal oxidation inO2, seeking an understanding of its poorer electrical quality as compared toSiO2–Si. It was found that the initial oxidation products are silicon oxycarbides(SiCxOy), while for longer oxidation times a mixture ofSiCxOyand SiO2is formed in the near surface region of the growing film. The composition of the near surface region of such thin films is very similar to that reported in previous investigations for the near interface region when thicker oxides films are grown on SiC.