Semiconductor devices having phase change memory cells, electronic systems employing the same and methods of fabricating the same

A semiconductor memory device comprising:

• a semiconductor substrate;
• a molding layer disposed over the semiconductor substrate, the molding layer having a top surface, and a protrusion extending vertically from the top surface of the molding layer;
• a phase-changeable material pattern having one portion thereof overlying the protrusion of the molding layer, and another portion thereof extending through the protrusion of the molding layer, and
• an oxidation barrier comprising electrically insulative material extending along and covering at least an area at which said one portion of the phase-change material pattern and the protrusion of the molding layer adjoin,
• wherein the oxidation barrier comprises a lower oxidation barrier spacer of electrically insulative material that extends along and covers a sidewall of the phase-change material pattern and a sidewall of the protrusion, an upper oxidation barrier layer of electrically insulative material, and a stress-alleviating buffer layer sandwiched between opposing surfaces of the lower oxidation barrier spacer and the upper oxidation barrier layer.

A semiconductor memory device comprising:

• a semiconductor substrate;
• a molding layer disposed over the semiconductor substrate, the molding layer having a top surface, a bottom surface, a protrusion extending vertically from the top surface so as to have a sidewall and an upper surface, and a contact hole extending through the protrusion from the upper surface thereof;
• a pattern of phase-changeable material self-aligned with the protrusion of the molding layer,
• wherein the pattern of phase-changeable material has an upper portion disposed on the protrusion of the molding layer, the upper portion having a sidewall whose contour is substantially the same as the contour of the sidewall of the protrusion of the molding layer, and
• wherein the pattern of phase-changeable material has a lower portion extending from the upper portion into the contact hole of the molding layer and through the protrusion of the molding layer by way of the contact hole;
• and
• an oxidation barrier comprising electrically insulative material covering at least part of the upper portion of the pattern of phase-changeable material, and the electrically insulative material conforming to the underlying topography of the device.