Phase-change memory element and method for fabricating the same

A method for fabricating a phase-change memory element, comprising:

• providing a first electrode on the substrate;
• forming a first dielectric layer with an opening on the first electrode, wherein the opening exposes a top surface of the first electrode;
• conformally forming a second dielectric layer on the first dielectric layer, covering the side walls and the bottom surface of the opening;
• forming a non-phase-change material layer on the second dielectric layer as a blanket film;
• performing a first planarizing process to remove a portion of the second dielectric layer and the non-phase-change material layer with the first dielectric layer acting as a stop layer, leaving a non-phase-change material pillar and a remaining second dielectric layer;
• etching the remaining second dielectric layer with the non-phase-change material pillar as an etching mask, leaving a second dielectric pillar, wherein the non-phase-change material pillar and the second dielectric pillar comprises a pillar structure;
• conformally forming a phase-change material layer on the first dielectric layer, the exposed top surface of the first electrode and the pillar structure, defining a collar opening;
• forming a third dielectric layer on the phase-change material layer as a blanket film, filling the collar opening;
• performing a second planarizing process to remove a portion of the phase-change material layer and the third dielectric layer with the first dielectric layer acting as a stop layer, leaving an inner phase-change material layer surrounding the pillar structure, a remaining third dielectric layer surrounding the inner phase-change material layer, an outer phase-change material layer surrounding the remaining third dielectric layer, and a phase-change material collar formed directly below the remaining third dielectric layer and connecting the inner phase-change material layer and the outer phase-change material layer;
• and
• forming a second electrode formed directly on the pillar structure, directly contacting the top surface of the inner phase-change material layer.