A Design of Experiments Framework for Magnetron-Sputtered HfO _x in Wafer-Scale Memristive Devices

High Resolution Image Download MS PowerPoint Slide Sub-stoichiometric hafnium oxide (HfO x ) is a key material for memristive devices in neuromorphic and nonvolatile memory applications, where precise control of thin-film properties is essential for tailored device performance. Magnetron sputtering offers this control but involves strongly coupled process parameters that hinder systematic optimization. In this work, we investigate the growth of HfO x films for wafer-scale memristive device fabrication using a multimodal characterization approach that combines X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) and large-area electrical testing. We demonstrate how HfO x thin films can be tailored to exhibit well-controlled sub-stoichiometry, a nanocrystalline structure with tensile strain, and grain sizes comparable to the film thickness. Based on these results, we propose a physically interpretable conceptual model that captures established cause-and-effect relationships between sputtering parameters, such as the argon-to-oxygen flow ratio, and resulting material properties. The model enables multi-objective optimization of material properties within the explored parameter space toward a structured Design of Experiments framework, providing a systematic alternative to empirical trial-and-error methods. This approach accelerates thin-film process development and applies to other oxide materials and emerging memory device architectures.