Fabrication and evaluation of nanopillar-shaped phase-change memory devices

In this study, nanopillar-shaped phase-change memory devices of various sizes were simply fabricated by nanosphere lithography, and their electrical characteristics were evaluated by conductive atomic force microscopy (AFM). As nanosphere materials, 180-nm diameter polystyrene balls were used for a size-controllable mask, silica balls with a diameter of 200nm for a high etching-resistance mask, and sub-50nm Ag nanoparticles were used for sub-50-nm-scale fabrication. Using the polystyrene balls, silica balls, and Ag nanoparticles, nanopillar-shaped phasechange memory devices with various diameters, heights as large as 1 μm, and sizes as small as less than 50nm were successfully fabricated. The electrical properties of the nanopillar-shaped Ge₂Sb₂Te₅ devices were evaluated by conductive AFM with an electrical measurement system.