Phase change memory cell with self-aligned vertical heater and low resistivity interface
View Patent ↗A low resistivity interface material is provided between a self-aligned vertical heater element and a contact region of a selection device. A phase change chalcogenide material is deposited directly on the vertical heater element. In an embodiment, the vertical heater element in L-shaped, having a curved vertical wall along the wordline direction and a horizontal base. In an embodiment, the low resistivity interface material is deposited into a trench with a negative profile using a PVD technique. An upper surface of the low resistivity interface material may have a tapered bird-beak extension.
1. A phase change memory cell comprising:
a first selection device and a second selection device respectively associated with a first phase change memory cell and a second phase change memory cell, the first and the second selection devices disposed along a wordline direction;
a contact region on said selection devices;
an interface layer in direct contact with said contact region;
an L-shaped vertical heater element in direct contact with said interface layer, wherein said L-shaped vertical heater element includes a curved vertical wall and a horizontal base, wherein the vertical wall and the horizontal base of the L-shaped vertical heater element respectively have a height and a length that perpendicularly extend, and wherein said curved vertical wall of said L-shaped vertical heater element has a width extending perpendicular to a direction of the length of horizontal base and extending along said wordline direction; and
a phase change material in direct contact with said vertical heater element, wherein the first and the second selection devices are separated along the wordline direction by a trench isolation that extends into and terminates within a wordline under the first and the second selection devices.
2. The phase change memory of claim 1 , wherein said contact region is a silicide, and said first selection device is a pnp-BJT.
3. The phase change memory of claim 1 , wherein said phase change material comprises a chalcogenide.
4. The phase change memory of claim 1 , wherein said vertical heater element comprises a metal nitride.
5. The phase change memory of claim 1 , wherein said interface layer is a metallic layer.
6. The phase change memory of claim 5 , wherein said metallic layer comprises a metal selected from the group consisting of cobalt, titanium, tantalum, and tungsten.
7. The phase change memory of claim 5 , wherein said metallic layer has a thickness of approximately 5 to 10 nm.
8. The phase change memory of claim 1 , wherein an uppermost portion of said interface layer comprises a tapered bird-beak extension.
9. The phase change memory of claim 1 , further comprising a spacer disposed on said horizontal base.
10. A phase change memory array comprising:
a plurality of selection devices extending along a wordline direction;
a silicide contact region on each of said plurality of selection devices;
an interface material formed on an in direct contact with each of said silicide contact regions;
a plurality of L-shaped heater elements each comprising a curved vertical wall and a horizontal base, the vertical wall and the horizontal base of the L-shaped vertical heater element respectively having a height and a length that perpendicularly extend, the vertical wall having a width extending perpendicular to a direction of the length of horizontal base and extending along said wordline direction of said phase change memory array, and each L-shaped heater element being in direct contact with said interface material; and
a phase change material in direct contact with said plurality of L-shaped heater elements;
wherein said plurality of L-shaped heater elements are self-aligned with said phase change material extending along a bitline direction of said phase change memory array, wherein the plurality of selection devices are separated along the wordline direction by a trench isolation that extends into and terminates within a wordline under the plurality of selection devices.
11. The phase change memory array of claim 10 , wherein an uppermost portion of said interface material comprises a tapered bird-beak extension.
12. A phase change memory array comprising:
a plurality of selection devices arranged in a plurality of rows along a wordline direction and in a plurality of columns along a bitline direction;
a contact region on each of said plurality of selection devices;
a plurality of interface materials each formed in direct contact with said contact region;
a plurality of L-shaped heater elements extending along said wordline direction and in direct contact with said plurality of interface materials, wherein each L-shaped vertical heater element includes a curved vertical wall and a horizontal base, wherein the vertical wall and the horizontal base of the L-shaped vertical heater element respectively have a height and a length that perpendicularly extend, and wherein the curved vertical wall of said L-shaped vertical heater element has a width extending perpendicular to a direction of the length of horizontal base and extending along said wordline direction; and
a phase change material in direct contact with said plurality of L-shaped heater elements,
wherein each row of said plurality of rows of selection devices is separated from an adjacent row of said plurality of rows of selection devices by a first trench isolation, and wherein each column of said plurality of columns of selection devices is separated from an adjacent column of said plurality of columns of selection devices by a second trench isolation that extends into and terminates within a wordline under the plurality of selection devices and is shallower than said first isolation.
13. The phase change memory array, wherein said contact region comprises silicide.