Structural and electrical characteristics of a high-k Lu ₂O ₃ charge trapping layer for nonvolatile memory application

In this article, we reported a metal-oxide-high-k-oxide-silicon (MOHOS)-type memory structure fabricating a high-k Lu ₂O ₃ film as a charge trapping layer for flash memory applications. X-ray diffraction and X-ray photoelectron spectroscopy revealed the structural and chemical features of these films after they had been subjected to annealing at various temperatures. The high-k Lu ₂O ₃ MOHOS-type devices annealed at 800°C exhibited a larger threshold voltage shift (memory window of ∼2.93 V operated at V _g = 9 V at 1 s) and better data retention (charge loss of ∼18% measured time up to 10 ⁴ s) than that had been subjected to other annealing conditions. This result suggests the higher probability for trapping of the charge carrier due to the formation of the crystallized Lu ₂O ₃ with a high dielectric constant of 12.8.