LaAlO₃/Si capacitors: Comparison of different molecular beam deposition conditions and their impact on electrical properties Available to Purchase

A study of the structural and electrical properties of amorphous LaAlO₃ (LAO)/Si thin films fabricated by molecular beam deposition (MBD) is presented. Two substrate preparation procedures have been explored namely a high temperature substrate preparation technique—leading to a step and terraces surface morphology—and a chemical HF-based surface cleaning. The LAO deposition conditions were improved by introducing atomic plasma-prepared oxygen instead of classical molecular O₂ in the chamber. An Au/Ni stack was used as the top electrode for its electrical characteristics. The physico-chemical properties (surface topography, thickness homogeneity, LAO/Si interface quality) and electrical performance (capacitance and current versus voltage and TunA current topography) of the samples were systematically evaluated. Deposition conditions (substrate temperature of 550 °C, oxygen partial pressure settled at 10⁻⁶ Torr, and 550 W of power applied to the O₂ plasma) and post-depositions treatments were investigated to optimize the dielectric constant (κ) and leakage currents density (J_Gate at |V_Gate| = |V_FB − 1|). In the best reproducible conditions, we obtained a LAO/Si layer with a dielectric constant of 16, an equivalent oxide thickness of 8.7 Å, and J_Gate ≈ 10⁻²A/cm². This confirms the importance of LaAlO₃ as an alternative high-κ for ITRS sub-22 nm technology node.