A nonvolatile memory cell includes a substrate and a phase changeable pattern configured to retain a state of the memory cell, on the substrate. An electrically insulating layer is provided, which contains a first electrode therein in contact with the phase changeable pattern. The first electrode has at least one of an L-shape when viewed in cross section and an arcuate shape when viewed from a plan perspective. A lower portion of the first electrode may be ring-shaped when viewed from the plan perspective. The lower portion of the first electrode may also have a U-shaped cross-section. An upper portion of the first electrode may also have an arcuate shape that spans more than 180° of a circular arc.