Diagnostics of process plasma used for the production of memristive devices

Abstract

Abstract Memristive devices have been the object of intensive studies for non-volatile memories, neuromorphic engineering and image processing algorithms. The intrinsic properties of these devices are determined by its I-V characteristics influenced by different process parameters. The double-barrier memristive devices investigated in this work are based on the motion of charged species, i.e. oxygen vacancies or ions, within a NbOx layer. Since the layers are deposited by magnetron sputtering, it is important to understand the physics of the discharge and its effect on the film properties. For plasma diagnostics we used a calorimetric probe, which can be operated simultaneously as a passive thermal probe for energy flux measurement and as a planar Langmuir probe for measuring the ion current, the floating and plasma potentials and the electron temperature. In particular, we investigated the reactive sputter deposition of the NbOx layer by a floating and a biased probe. The parameters were determined in dependence on the radial position of the probe across the substrate region. The results allowed us to find correlations between the plasma parameters and the electrical properties of the memristive devices produced on one 100-mm wafer. Furthermore, we could point out the dominating factors affecting strongly the properties of these thin films.