Phase change memory with gradual resistance change
View Patent ↗A phase change memory cell is provided that includes a phase change material-containing structure sandwiched between first and second electrodes. The phase change material-containing structure has a resistance that changes gradually, and thus may be used in analog or neuromorphic computing. The phase change material-containing structure may contain a plurality of phase change material pillars, wherein each phase change material pillar has a different phase change material composition. Alternatively, the phase change material-containing structure may contain a doped phase change material layer in which a dopant concentration decreases laterally inward from an outermost surface thereof.
1. A semiconductor structure comprising:
a phase change memory cell located on a surface of a semiconductor substrate, wherein the phase change memory cell comprises a material stack of, and from bottom to top, a first electrode, a phase change material-containing structure having a resistance that changes gradually, and laterally inward, from an outermost surface, and a second electrode, wherein the phase change material-containing structure comprises a doped phase change material layer in which a dopant concentration of the doped phase change material layer decreases laterally inward from an outermost surface of the doped phase change material layer.
2. The semiconductor structure of claim 1 , wherein the first electrode has an outermost sidewall that is vertically aligned to an outermost sidewall of both the phase change material-containing structure and the second electrode.
3. The semiconductor structure of claim 1 , wherein the doped phase change material layer is a single layered material.
4. The semiconductor structure of claim 3 , wherein the doped phase change material layer is composed of a doped chalcogenide.
5. The semiconductor structure of claim 1 , wherein the doped phase change material layer comprises a germanium doped GeSbTe alloy.
6. The semiconductor structure of claim 1 , wherein the doped phase change material layer comprises a tin doped SbTe alloy.
7. The semiconductor structure of claim 1 , wherein the doped phase change material layer comprises a germanium doped InSe alloy.
8. The semiconductor structure of claim 1 , further comprising a dielectric spacer located along an entire sidewall of the phase change memory cell.
9. The semiconductor structure of claim 8 , further comprising an interlevel dielectric material layer laterally adjacent to the dielectric spacer.
10. The semiconductor structure of claim 9 , wherein the interlevel dielectric material layer has a topmost surface that is coplanar with a topmost surface of the dielectric spacer and a topmost surface of the second electrode.
11. The semiconductor structure of claim 1 , further comprising an interlevel dielectric material layer located along an entire sidewall of the phase change memory cell and located on the semiconductor substrate.
12. The semiconductor structure of claim 11 , wherein the interlevel dielectric material layer has a topmost surface that is coplanar with a topmost surface of the second electrode.
13. The semiconductor structure of claim 1 , wherein a bottommost surface of the first electrode is located directly on a topmost surface of the semiconductor substrate.
14. The semiconductor structure of claim 1 , wherein the first electrode is composed of titanium nitride, tungsten, tungsten nitride, silicon, platinum, palladium or aluminum.
15. The semiconductor structure of claim 1 , wherein the second electrode is composed of titanium nitride, tungsten, tungsten nitride, silver, platinum, palladium or aluminum.
16. The semiconductor structure of claim 1 , wherein the first electrode is composed of a first conductive material and the second electrode is composed of a second conductive material, wherein the first and second conductive materials are compositionally the same.
17. The semiconductor structure of claim 1 , wherein the first electrode is composed of a first conductive material and the second electrode is composed of a second conductive material, wherein the first and second conductive materials are compositionally different.
18. The semiconductor structure of claim 1 , wherein a first surface of the phase change material-containing structure directly contacts a surface of the first electrode, and a second surface of the phase change material-containing structure, opposite the first surface, directly contacts a surface of the second electrode.