Electronic Properties of the Interface Formed by Pr 2 O 3 Growth on Si(001), Si(111) and SiC(0001) Surfaces

The control of interface parameters is the most crucible effort in device technology. With the demand of down scaling to a 65-nm technology node the use of high-k materials and the partial or complete replacement of SiO2 is emphasized [1,2]. A critical measure of the achieved improvement is the equivalent oxide thickness (EOT) in which the physical thickness of the dielectric layer is scaled by the ratio of DK (SiO2) / DK (dielectric). In device applications the EOT should be smaller than 1 nm. To do so it is important not only to increase the DK of the dielectric but also to minimize the formation of an interfacial SiO2 layer. It is evident that this demand is an ultimate challenge for materials science, surface and interface characterization, and technical engineering. We employ state-of-the-art interface characterization techniques involving synchrotron radiation (SR) excited photoelectron spectroscopy (PES) for the characterization of the hetero-oxide-Si interfaces. We report nondestructive depth profiling by varying the escape depth, give an analysis of intermediate oxidation states and chemical state of interface species to follow the silicate formation Si2p, and report on the use of X-ray absorption spectroscopy (XAS) in materials science. Our contribution to that field is the control of film growth, interface reactivity, and phase homogeneity in ultra-thin oxide films by applying surface science techniques and employing SR based electron spectroscopies for their analysis. We explain our experimental setup, report on the Pr2O3 / Si(001) interface, which is one of the few candidates to realize a EOT <1 nm dielectric barrier on Si-surfaces. We compare these data to the corresponding results obtained at Si(111) and at SiC(0001) surfaces. For the latter, the high-k materials would enable considerable progress in high frequencies and high-power applications, while the former are requested by future Si technology nodes.

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