Phase change material device and methods for forming the same

A method of forming a device structure, comprising:

• forming a bottom electrode, a dielectric material layer, and a via opening extending through the dielectric material layer such that a top surface segment of the bottom electrode is exposed underneath the via opening;
• depositing a heater liner layer within a fraction of a volume of the via opening and over the dielectric material layer;
• vertically recessing a horizontally-extending portion of the heater liner layer;
• depositing a phase change material layer comprising a phase change material and a top electrode material layer over the horizontally-extending portion of the heater liner layer;
• and
• patterning the top electrode material layer, the phase change material layer, and the heater liner layer into a layer stack including a heater liner, a phase change material portion, and a top electrode.

A device structure comprising:

• a tubular dielectric spacer located within a via opening in a dielectric material layer;
• a heater liner comprising a vertically-extending portion laterally surrounded by the tubular dielectric spacer and a horizontally-extending portion overlying a top surface segment of the dielectric material layer;
• a phase change material portion comprising a phase change material contacting a top surface of the heater liner;
• and
• a top electrode contacting a top surface of the phase change material portion.