Heat-flow controlled phase change material device with sidewall liners and methods for forming the same

A method of forming a device structure, comprising:

• forming bottom electrodes and heater elements within a dielectric material layer;
• forming in-process layer stacks of a respective in-process bottom liner, a respective in-process phase change material portion, and a respective in-process top electrode;
• forming in-process sidewall liners on the in-process layer stacks;
• and
• patterning the in-process layer stacks and the in-process sidewall liners, wherein:
• patterned portions of the in-process layer stacks comprise layer stacks;
• patterned portions of the in-process sidewall liners comprise sidewall liners;
• and
• phase change material portions within a first subset of the layer stacks comprises a respective sidewall facing a first outward surface normal direction having an azimuthal angle with respect to a first horizontal direction as measured along a clockwise direction, and further comprises a respective additional sidewall facing a horizontal direction that is different from the first outward surface normal direction and is physically exposed to a surrounding gaseous environment.

A device structure comprising:

• phase change memory cells, wherein:
• each of the phase change memory cells comprises a respective layer stack including a bottom liner, a phase change material portion comprising a phase change material, and a top electrode;
• a first subset of the phase change memory cells is configured to generate a first temperature gradient along a first lateral direction that is rotated from a first horizontal direction in a clockwise direction by a first azimuthal angle in a top-down view;
• and
• a second subset of the plurality of phase change memory cells is configured to generate a second temperature gradient along a second lateral direction that is rotated from the first horizontal direction in the clockwise direction by a second azimuthal angle in the top-down view, the second azimuthal angle being different from the first azimuthal angle.