Phase change memory cell with tubular heater and manufacturing method thereof
View Patent ↗A phase change memory cell includes a phase change region of a phase change material, a heating element of a resistive material, arranged in contact with the phase change region and a memory element formed in said phase change region at a contact area with the heating element. The contact area is in the form of a frame that has a width of sublithographic extent and, preferably, a sublithographic maximum external dimension. The heating element includes a hollow elongated portion which is arranged in contact with the phase change region.
1. A phase change memory cell comprising:
a phase change region of a phase change material; and
a heating element of a resistive material, arranged in contact with said phase change region along an entire contact area, the phase change region including a memory element adjacent to the contact area, wherein said heating element is in the form of a frame having a thickness defined by an external perimeter and an internal perimeter, the external perimeter having a first linear cross-dimension from a first side of the external perimeter to an opposite, second side of the external perimeter that is less than 100 nm;
a dielectric sheath film positioned within the inner perimeter of the heating element frame, the sheath film being shaped as a frame having a central opening; and
a conductive core centrally located within the frame of the heating element and completely filling the opening of the dielectric sheath film.
2. A memory cell according to claim 1 , wherein said contact area has a second linear cross-dimension from a third side of the external perimeter to an opposite, fourth side of the external perimeter that is less than 100 nm, the first and second linear cross-dimensions being substantially perpendicular to one another.
3. A memory cell according to claim 1 , wherein said heating element includes a hollow elongated portion defined by a tubular element.
4. A memory cell according to claim 3 , wherein said hollow elongated portion extends to the contact area in contact with said phase change region.
5. A memory cell according to claim 4 , wherein the external perimeter of said heating element has a has a maximum external cross-dimension that is less than 100 nm.
6. A memory cell according to claim 1 , wherein said conductive core is of metal.
7. A memory cell according to claim 1 , wherein said conductive core is directly in contact with said phase change region.
8. A memory cell according to claim 3 , wherein said heating element is at least partially embedded in a structural layer.
9. A memory cell according to claim 8 , further comprising adhesion regions arranged between said structural layer and said phase change region.
10. A process for manufacturing a phase change memory cell, comprising the steps of:
forming a heating element, of a resistive material; and
forming a phase change region, of a phase change material, on and in contact with said heating element along an entire contact area, thereby forming a memory element in said phase change region adjacent to the contact area of said phase change region and of said heating element;
wherein said heating element is in the form of a frame having a thickness defined by an external perimeter and an internal perimeter, the external perimeter having a first linear cross-dimension from a first side of the external perimeter to an opposite, second side of the external perimeter that is less than 100 nm;
forming a dielectric sheath film positioned within the inner perimeter of the heating element frame, the sheath film including a frame having a central opening; and
forming a conductive core centrally located within the frame of the heating element and completely filling the opening of the dielectric sheath film.
11. A process according to claim 10 , wherein the external perimeter of said contact area and heating element have a second linear cross-dimension from a third side of the external perimeter to an opposite, fourth side of the external perimeter that is less than 100 nm, the first and second linear cross-dimensions being substantially perpendicular to one another.
12. A process according to claim 10 , wherein said step of forming said heating element comprises:
forming an opening in a structural layer; and
conformally depositing a heater layer of said resistive material on said structural layer and in said opening, a thickness of said heater layer being less than 100 nm.
13. A process according to claim 12 , wherein said contact area has a maximum external dimension less than 100 nm and the step of forming an opening includes forming a lithographic opening having a lithographic cross-dimension and narrowing said lithographic opening to a cross-dimension which is equal to said maximum external dimension.
14. A process according to claim 13 , wherein said step of narrowing includes forming spacers inside said lithographic opening.
15. A process according to claim 12 , wherein said step of forming said phase change region comprises depositing a phase change layer directly on said structural layer and in contact with said heating element.
16. A process according to claim 12 , wherein an adhesion layer is deposited on said structural layer before forming said heating element.
17. A process according to claim 16 , wherein said step of forming said phase change region comprises depositing a phase change layer on said adhesion layer after forming said heating element.
18. A process according to claim 17 , wherein said phase change layer is deposited in contact with said heating element.
19. A process according to claim 16 , further comprising the step of removing said adhesion layer outside said phase change region.
20. A process according to claim 16 , wherein said adhesion layer is of metal.
21. A phase change memory device, comprising:
a plurality of phase change memory cells, each memory cell including:
a phase change region of a phase change material;
a heating element of a resistive material, arranged in contact with said phase change region along an entire contact area, the phase change region including a memory element adjacent to the contact area, wherein said heating element is in the form of a frame having a thickness defined by an external perimeter and an internal perimeter, the external perimeter having a first linear cross-dimension from a first side of the external perimeter to an opposite, second side of the external perimeter that is less than 100 nm;
a dielectric sheath film positioned within the inner perimeter of the heating element frame, the sheath film being shaped as a frame having a central opening; and
a conductive core centrally located within the frame of the heating element and completely filling the opening of the dielectric sheath film.
22. A memory device according to claim 21 , wherein said contact area has a second linear cross-dimension from a third side of the external perimeter to an opposite, fourth side of the external perimeter that is less than 100 nm, the first and second linear cross-dimensions being substantially perpendicular to one another.
23. A memory device according to claim 21 , wherein said heating element includes a hollow elongated portion defined by a tubular element.
24. A memory device according to claim 21 , wherein said heating element includes a hollow elongated portion that is filled with the conductive core and is electrically isolated therefrom by the sheath film.
25. A memory device according to claim 24 , wherein said conductive core is directly in contact with said phase change region.
26. A system comprising:
a processing unit;
an interface coupled to said processing unit; and
a nonvolatile phase change memory device, coupled to said processing unit and including a plurality of phase change memory cells, each phase change memory cell including:
a phase change region of a phase change material;
a heating element of a resistive material, arranged in contact with said phase change region along an entire contact area, the phase change region including a memory element adjacent to the contact area, wherein said heating element is in the form of a frame having a thickness defined by an external perimeter and an internal perimeter, the external perimeter having a first linear cross-dimension from a first side of the external perimeter to an opposite, second side of the external perimeter that is less than 100 nm;
a dielectric sheath film positioned within the inner perimeter of the heating element frame, the sheath film being shaped as a frame having a central opening; and
a conductive core centrally located within the frame of the heating element and completely filling the opening of the dielectric sheath film.
27. A system according to claim 26 , wherein said interface is a wireless interface.
28. A system according to claim 26 , wherein said heating element includes a hollow elongated portion that is filled with the conductive core and is electrically isolated therefrom by the dielectric sheath film.
29. A phase change memory cell comprising:
a phase change region of a phase change material;
a heating element of a resistive material, arranged in contact with said phase change region along an entire contact area, the phase change region including a memory element adjacent to the contact area, wherein said heating element is in the form of a frame having a thickness defined by an external perimeter and an internal perimeter, the external perimeter having a first linear cross-dimension from a first side of the external perimeter to an opposite, second side of the external perimeter that is less than 100 nm
a sheath film of a dielectric material positioned within the inner perimeter of the heating element frame, the sheath film including a frame having a central opening; and
a conductive core centrally located within the frame of the heating element and completely filling the opening of the sheath film.
30. A memory cell according to claim 29 , wherein said contact area has a second linear cross-dimension from a third side of the external perimeter to an opposite, fourth side of the external perimeter that is less than 100 nm, the first and second linear cross-dimensions being substantially perpendicular to one another.
31. A memory cell according to claim 29 , wherein said heating element includes hollow elongated portion defined by a tubular element.
32. A memory cell according to claim 29 , wherein said conductive core is directly in contact with said phase change region.
33. A memory cell according to claim 29 , further comprising:
a structural layer in which said heating element is at least partially embedded; and
adhesion regions arranged between said structural layer and said phase change region.