Epitaxial, well-ordered ceria/lanthana high-k gate dielectrics on silicon

Abstract

It is shown that the growth of epitaxial lanthana films on silicon may be achieved by substrate prepassivation using an atomic layer of chlorine, which prevents silicon oxide and silicate formation at the oxide–silicon interface. Postdeposition of two layers of cerium oxide facilitates the healing of structural defects within the La2O3 film, strongly increasing its crystallinity at the expense of a slightly more oxidized interfacial layer below. Together, the approach of combining Cl prepassivation and the ceria overgrowth results in an epitaxial, high-quality ceria/lanthana gate stack suitable for high-k integration in a gate-last process.

Controlling the physics and chemistry of binary and ternary praseodymium and cerium oxide systems

“…It is important to note that this approach fundamentally differs from the growth of ultra-thin films on metal surfaces often used for surface science studies in this field. [75][76][77][78][79][80][81][82][83][84][85][86][87][88] While basic atomic and defect structures of ultra-thin films can be assumed to be similar to surfaces of bulk oxide crystals, the ultra-thin film does not provide a significant reservoir of oxygen that is important for understanding surface processes depending on an interaction between the surface and volume. For this reason, in the context of the work reported here, mostly films of a thickness ranging from some tens to some hundreds of nm are used rather than films having a thickness of only a few atomic layers.…”

Potential of La-Doped SrTiO3 Thin Films Grown by Metal–Organic Vapor Phase Epitaxy for Thermoelectric Applications

“…In the case of La, the signal-to-noise ratio is limited by the low concentrations. Nevertheless, we report similar spectra exhibiting the characteristic multiplet splitting of the two spin–orbit split components La 3d 3/2 and La 3d 5/2 for the three samples, especially for La concentrations of 0.05 and 0.17 mM (0.03 mM sample is in the detection limit), which are also very similar to what has been previously reported in La-doped SrTiO 3 films and La 2 O 3 films on silicon . Moreover, Figure d shows the La 3d 5/2 fit following the model reported by Sunding et al for La 2 O 3, also supporting the incorporation of lanthanum with La 3+ oxidation state.…”

Structural Properties Characterized by the Film Thickness and Annealing Temperature for La2O3 Films Grown by Atomic Layer Deposition

“…On the one hand, featuring with high dielectric constant (approximately 27) and large band offsets with silicon (over 2 eV), La 2 O 3 is one among the most promising high-k dielectric materials to replace SiO 2 and Si 3 N 4 in advanced metal-oxide gate stack in semiconductor devices [4]. Up to now, benefiting from the approach of surface passivation prior to oxide deposition, high-quality ceria/lanthana gate stack suitable for high-k integration in a gate-last process has been accomplished [5]. On the other hand, La 2 O 3 is usually used as a kind of effective dopant in thermionic emitters [6], ferroelectric ceramics [7], and oxide catalysts [8], in order to improve properties such as emission capability, effective dielectric constant, and catalytic activity.…”