Driving force of oxygen-ion migration across high-k/SiO₂ interface

Abstract

We clarified the mechanism of oxygen (O−)-ion migration at a high-k/SiO2 interface, which is a possible origin of the flat-band voltage shift in metal/high-k gate stacks. The oxygen density difference accommodation model was reproduced by a molecular dynamics simulation of an Al2O3/SiO2 structure, in which O− ions migrate from the higher oxygen density side to the lower one. We determined that the driving force of the O−-ion migration is the short-range repulsion between ionic cores. The repulsive force is greater in materials with a higher oxygen density, pushing O− ions to the lower oxygen density side.

Interface Chemistry and Defect State Optimization of the ErSmO/InP Heterojunction Modified by ALD-Driven Al2O3 Interlayers

“…Table lists the extracted electrical parameters, including the dielectric constant ( k ), equivalent oxide thickness (EOT), flat-band voltage ( V fb ), and oxide charge density ( Q ox ). The shift in flat-band voltage is related to the dipole between the high-k/interface layers, and the oxygen density difference accommodation model applies to the explanation of interface dipole layer generation owing to its wide support in high-k materials . The dipole layer arises through the migration of O ions from high to low concentrations, leading to the formation of an internal electric field at the interface, while the direction and magnitude of the internal electric field are consistent with the observed flat-band voltage shift. , The dipole species at the ErSmO dielectric/InP interface have an impact on the flat-band voltage shift, and during preparation, the high-k dielectric diffuses into the Al 2 O 3 /InP interface, where the Er and Sm elements are less electronegative than Al and form dipoles with stronger polarities, which can lead to negative flat-band voltage shifts, as indicated by the detected negative flat-band voltages .…”

Training dependency of neural network interatomic potential for molecular dynamics simulation of Ru-Si-O mixed system

“…Interface Dataset (II) further includes the data points reflecting those of Ru and SiO 2 -slab models as surface structures which are non-interface structures. We also prepared interface test sets including the data points of the SiO 2 /Ru/SiO 2 stacking structures with Ru[0001]/SiO 2 and Ru [11][12][13][14][15][16][17][18][19][20]/SiO 2 interfaces. Each interface test set includes 33 data points.…”

“…Molecular dynamics (MD) simulations based on interatomic potential are suited for the assessments, thanks to its low computational cost of large-scale atomistic modeling of interconnects, 10) dielectrics, [11][12][13] and silicide metals. 14) The first step in performing MD simulations is to develop interatomic potential.…”

(Invited) Molecular Dynamics of Dipole Layer Formation at High-k/SiO2Interface

“…The difference between the octupole and hexadecapole moments was considered to be a possible candidate of the driving force of O ion migration. However, the subsequent analysis [16] clarified that the dominant force acting on O ions near the interface does not originate from the charge-to-charge interaction. Thus, the previous hypothesis is refuted.…”