Patent ID: 7173271

Claim:
A phase-change memory device comprising: a semiconductor substrate having a bottom structure; a dielectric interlayer formed on the semiconductor substrate and covering the bottom structure; a contact plug formed within the dielectric interlayer; a bottom electrode formed on the contact plug and a portion of the dielectric interlayer adjacent to the contact plug; a first oxide layer formed on the dielectric interlayer and the bottom electrode and having a contact hole for exposing the bottom electrode formed within the first oxide layer; a spacer formed on a side surface of the contact hole and on a first annular-shaped area of the bottom electrode: a phase-change layer formed on the spacer and on a second annular shaped area on the bottom electrode that is within the first annular shaped area, said phase-change layer having substantially the same cross-sectional shape of said spacer, said phase-change layer being sized, shaped and arranged to appear to have a doughnut-shape when viewed from a plan view of said phase-change layer, the bottom of said phase-change lever contacting the bottom electrode through said second annular contact area, the top of said phase-change layer contacting a top electrode through an upper contact area of the phase-change layer that is away from the bottom of said phase-change layer; a second oxide layer filling in the contact hole while exposing an upper portion of the phase-change layer; and said top electrode formed on the first oxide layer while being in contact with the upper portion of the phase-change layer.