Self-assembly of Ni nanocrystals on HfO2 and N-assisted Ni confinement for nonvolatile memory application

Abstract

We demonstrate memory property using Ni nanocrystals with mean diameter of 9nm embedded in HfO2 high-k dielectric that are formed via a self-assembly process by sputtering and rapid thermal annealing. X-ray photoelectron spectroscopy shows that Ni penetrates into the 5nm HfO2 after high temperature annealing above 800°C in N2. However, the diffusion is suppressed by N incorporation into HfO2 by NH3 annealing. Metal-oxide-semiconductor structures were fabricated with Ni nanocrystals embedded in HfO2. An additional counterclockwise hysteresis of 2.1V due to the charge trapping properties of the Ni nanocrystals was observed from a ±5V sweep during capacitance–voltage electrical measurement.