Self-aligned, planar phase change memory elements and devices
Phase change memory elements, devices and systems using the same and methods of forming the same are disclosed. A memory element includes first and second electrodes, and a phase change material layer between the first and second electrodes. The phase change material layer has a first portion with a width less than a width of a second portion of the phase change material layer. The first electrode, second electrode and phase change material layer may be oriented at least partially along a same horizontal plane.
1. A memory element comprising:
a substrate,
first and second electrodes, each located on a same horizontal plane that is parallel to the substrate;
first and second dielectric materials between the first and second electrodes; and
a planar phase change material between the first and second electrodes, located on the horizontal plane and vertically disposed between and in contact with the first and second dielectric materials such that the first and second dielectric materials and the phase change material form a stack, the first electrode formed on a first sidewall of the stack and the second electrode being formed on a second sidewall of the stack, the stack having at least first, second and third portions, the first portion having a width less than the widths of the second and third portions,
wherein the second portion is in contact with the first electrode and the third portion is in contact with the second electrode, wherein the first portion is between the second and third portions, wherein the second portion is between the first electrode and the first portion, and wherein the third portion is between the second electrode and the first portion, such that a programmable volume of the phase change material is not in contact with the first or second electrodes.
2. The memory element of claim 1 , wherein the first portion comprises the programmable volume.
3. The memory element of claim 1 , wherein a width of the stack progressively decreases from the second and third portions to the first portion.
4. The memory element of claim 1 , wherein the programmable volume is approximately centered between the first and second electrodes.
5. The memory element of claim 1 , further comprising at least one conductive plug, wherein the first electrode is in contact with the at least one conductive plug.
6. The memory element of claim 1 , wherein, the first and second electrodes are self-aligned to the phase change material.
7. The memory element of claim 3 , wherein a width of the stack decreases in a step-wise manner from the second and third portions to the first portion.
8. The memory element of claim 3 , wherein a width of the stack decreases linearly from the second and third portions to the first portion.
9. A memory device comprising:
at least two memory elements according to claim 1 ; and
a conductive interconnect, wherein the first and second electrodes of the at least two memory elements are located along the horizontal plane, and wherein the conductive interconnect is in contact with second electrodes of the at least two memory elements.