Surface characterisation and interface studies of high-k materials by XPS and TOF-SIMS

Abstract High-k dielectric LaAlO 3 (LAO) films on Si(100) were studied by TOF-SIMS and XPS to look for diffusion processes during deposition and additional thermal treatment and for the formation and composition of possible interfacial layers. The measurements reveal the existence of SiO 2 at the LAO/Si interface. Thermal treatment strengthens this effect indicating a segregation of Si. However, thin LAO layers show no interfacial SiO 2 but the formation of a La–Al–Si–O compound. In addition, Pt diffusion from the top coating into the LAO layers occurs. Within the LAO layer C is the most abundant contamination (10 21  at/cm 3 ). Its relatively high concentration could influence electric characteristics. XPS shows that CO 3 2− is intrinsic to the LAO layer and is due to the adsorption of CO 2 of the residual gas in the deposition chamber.