Contact structure and method for variable impedance memory element
View Patent ↗A memory element can include an opening formed within at least one insulating layer formed on an etch stop layer that exposes a first electrode portion and the etch stop layer at a bottom of the opening; a second electrode portion, formed on at least a side surface of the opening and in contact with the first electrode portion, the second electrode portion not filling the opening and being substantially not formed over a top surface of the at least one insulating layer; and at least one memory layer formed on a top surface of the at least one insulating layer and in contact with the second electrode portion, the at least one memory layer being reversibly programmable between at least two impedance states. Methods of forming such memory elements are also disclosed.
1. A memory element, comprising:
an opening formed within at least one insulating layer formed on an etch stop layer that exposes a first electrode portion and the etch stop layer at a bottom of the opening;
a second electrode portion, formed on at least a side surface of the opening and not formed over a top surface of the at least one insulating layer, the second electrode portion being in contact with the first electrode portion; and
at least one memory layer formed on a top surface of the at least one insulating layer and in contact with the second electrode portion, the at least one memory layer being reversibly programmable between at least two impedance states; wherein
the opening has no steps in its bottom surface for a low topography profile.
2. The memory element of claim 1 , wherein:
the etch stop layer is selected from the group of: silicon nitride and silicon oxynitride; and
the one insulating layer is formed from a material different than the etch stop layer.
3. The memory element of claim 1 wherein:
the second electrode portion comprises an annular shaped portion.
4. The memory element of claim 1 , wherein:
the second electrode portion comprises a conductive material selected from the group of: tantalum, tantalum nitride.
5. The memory element of claim 1 , wherein:
the at least one memory layer comprises a solid electrolyte; and
the second electrode portion comprises at least one metal oxidizable in the solid electrolyte.
6. The memory element of claim 1 , wherein:
the at least one memory layer is selected from the group of: a chalcogenide and a metal oxide.
7. The memory element of claim 1 , further including:
a fill insulator formed within the opening between portions of the second electrode formed on opposing sides of the opening.
8. A memory element, comprising:
an opening formed within at least a hard etch mask and at least one insulating layer that is formed on an etch stop layer, the opening exposing a first electrode portion at a bottom of the opening;
a second electrode portion, formed on at least a side surface of the opening and not over a top surface of the hard etch mask, the second electrode portion being in contact with the first electrode portion; and
at least one memory layer formed on a top surface of the hard etch mask and in contact with the second electrode portion, the at least one memory layer being reversibly programmable between at least two impedance states; wherein
the opening has no steps in its bottom surface for a low topography profile.
9. The memory element of claim 8 wherein:
the second electrode portion comprises an annular shaped portion.
10. The memory element of claim 8 , wherein:
the at least one memory layer comprises a solid electrolyte; and
the second electrode portions comprises at least one metal oxidizable in the solid electrolyte.
11. The memory element of claim 8 , wherein:
the at least one memory layer is selected from the group of: a chalcogenide and a metal oxide.
12. The memory element of claim 8 , further including:
a fill insulator formed within the opening between portions of the second electrode formed on opposing sides of the opening.
13. The memory element of claim 8 , further including:
an etch stop layer formed below the at least one insulating layer and in contact with the first electrode portion.
14. The memory element of claim 1 , wherein:
the at least one memory layer comprises a solid electrolyte; and
the second electrode portion is a cathode formed of materials that are not substantially oxidizable in the solid electrolyte.
15. The memory element of claim 1 wherein:
the second electrode portion comprises a sidewall shape, having a thickness that is smaller toward a top of the opening than at a bottom of the opening.
16. The memory element of claim 1 , wherein:
the second electrode portion comprises a metal selected from the group of: copper and silver.
17. The memory element of claim 1 , wherein:
the at least one insulating layer includes a hard etch mask layer formed over an interlayer insulator; wherein
the hard etch mask layer provides a high etch selectivity with respect to the interlayer insulator.
18. The memory element of claim 1 , wherein:
the first electrode portion includes
a first member formed from a first interconnect layer, and
a second member in contact with the first member, formed from a second interconnect layer.
19. The memory element of claim 7 , wherein:
the fill insulator is selected from the group of: silicon nitride and silicon oxide, including silicon oxide formed by the decomposition of tetraethyl orthosilicate (TEOS).
20. The memory element of claim 8 , wherein:
the at least one memory layer comprises a solid electrolyte; and
the second electrode portion is a cathode formed of materials that are not substantially oxidizable in the solid electrolyte.
21. The memory element of claim 8 wherein:
the second electrode portion comprises a sidewall shape, having a thickness that is smaller toward a top of the opening than at a bottom of the opening.
22. The memory element of claim 8 , wherein:
the second electrode portion comprises a metal selected from the group of: copper and silver.
23. The memory element of claim 1 , wherein:
the etch stop layer and the first electrode portion form at least a portion of a bottom surface of the opening.
24. The memory element of claim 1 , wherein:
the first electrode portion forms the bottom surface of the opening.