Physical and electrical properties of flash memory devices with nickel oxide(NiO ₂ ) charge trapping layer

In this study, we proposed a metal-oxide high-k-oxide-silicon (MOHOS) memory device using a nickel oxide film as the charge trapping layer, and studied the effect of post-deposition rapid thermal annealing (RTA) on the physical and electrical properties. The physical properties were investigated via multiple material analysis techniques such as X-ray diffraction and atomic force microscopy. The optimal annealing temperature for depositing the charge trapping layer was determined through a thorough investigation of the memory window, program/erase (P/E) cycle, crystalline structure, and material composition. Compared to the as-deposited NiO ₂ film, a MOHOS-type memory device annealed at 900 °C in a nitrogen atmosphere exhibited improved memory characteristics, in terms of a larger window in the capacitance-voltage hysteresis, better data retention (lower charge loss of 11%), faster program and erase cycles, and endurance characteristics (10 ⁴  P/E cycles) without any significant drift in the flat band voltage. Therefore, the MOHOS memory device with a NiO ₂ trapping layer is a very promising candidate for future memory device applications.