A memory device including a lower electrode having an upper portion extending above an upper surface of a first dielectric layer, wherein the upper portion of the lower electrode has corners that are exposed. The memory device also includes a metal oxide layer having a conformal thickness present on sidewalls of the upper portion of the lower electrode. The metal oxide layer is present on at least the corners of the lower electrode that extend above the first dielectric layer. The memory device may also include an upper electrode present on the metal oxide layer. The upper electrode being separated from an entirety of the lower electrode by the metal oxide layer. In some embodiments, the memory device is a resistive random access memory device. The corners of the lower electrode localize filament formation in the metal oxide layer.