Resistive random access memory device

Patent metadata

Field	Value
Publication number	US-2022013719-A1
Application number	US-201917295920-A
Country	US
Kind code	A1
Filing date	Sep 23, 2019
Priority date	Nov 21, 2018
Publication date	Jan 13, 2022
Grant date	—

Abstract

A resistive random access memory (ReRAM) device includes a bottom electrode and a top electrode with a switching layer disposed therebetween. The bottom electrode has a top surface in contact with a bottom surface of the switching layer. The bottom electrode also has first and second sidewalls spaced apart by a first distance where the sidewalls contact the bottom surface of the switching layer. The switching layer has first and second sidewalls spaced apart by a second distance that is larger than the first distance. The top electrode is disposed over the switching layer. The first sidewall of the switching layer overhangs the first sidewall of the bottom electrode by an overhang distance of 5 nanometers or more. The second sidewall of the switching layer overhangs the second sidewall of the bottom electrode by an overhang distance of 5 nanometers or more.

First claim

What is claimed is:

1 . A resistive random access memory (ReRAM) device comprising:
a bottom electrode and a top electrode with a switching layer disposed therebetween; the bottom electrode having a top surface in contact with a bottom surface of the switching layer, the bottom electrode having first and second sidewalls spaced apart by a first distance where the sidewalls contact the bottom surface of the switching layer; the switching layer having first and second sidewalls spaced apart by a second distance that is larger than the first distance; the top electrode disposed over the switching layer; wherein the first sidewall of the switching layer overhangs the first sidewall of the bottom electrode by an overhang distance of 5 nanometers or more; and wherein the second sidewall of the switching layer overhangs the second sidewall of the bottom electrode by an overhang distance of 5 nanometers or more.

2 . The ReRAM device of claim 1 , wherein:
the first sidewall of the switching layer overhangs the first sidewall of the bottom electrode by an overhang distance of 10 nanometers or more; and wherein the second sidewall of the switching layer overhangs the second sidewall of the bottom electrode by an overhang distance of 10 nanometers or more.

3 . The ReRAM device of claim 1 , wherein:
the first sidewall of the switching layer overhangs the first sidewall of the bottom electrode by an overhang distance of 15 nanometers or more; and wherein the second sidewall of the switching layer overhangs the second sidewall of the bottom electrode by an overhang distance of 15 nanometers or more.

4 . The ReRAM device of claim 1 , comprising:
one or more liners disposed over the first and second sidewalls and a bottom surface of the bottom electrode, the one or more liners having first and second distal ends that are in contact with the bottom surface of the switching layer; wherein the one or more liners are each composed of a material that does not react with the switching layer when in contact with the switching layer.

5 . The ReRAM device of claim 1 , comprising, an oxygen exchange layer (OEL) disposed between the switching layer and the top electrode, wherein the OEL reacts with the switching layer to remove some of the oxygen atoms from an upper portion of the switching layer.

6 . The ReRAM device of claim 1 , wherein the switching layer is composed of at least one of hafnium oxide, tantalum oxide and titanium oxide.

7 . The ReRAM device of claim 1 , wherein the switching layer is within a range of 2 to 20 nanometers thick.

8 . The ReRAM device of claim 1 , wherein the top and bottom electrodes are composed of at least one of tungsten, copper and titanium nitride.

9 . The ReRAM device of claim 1 , wherein the top and bottom electrodes are each within a range of 5 to 200 nanometers thick.

10 . The ReRAM device of claim 4 , wherein the one or more liners are composed of at least one of titanium oxide, tantalum nitride, iridium and ruthenium.

11 . A resistive random access memory (ReRAM) device comprising:
a bottom electrode and a top electrode with a switching layer disposed therebetween; the bottom electrode having a top surface in contact with a bottom surface of the switching layer; the top electrode disposed over the switching layer; and one or more liners disposed over first and second sidewalls and a bottom surface of the bottom electrode, the one or more liners having first and second distal ends that are in contact with the bottom surface of the switching layer; wherein the one or more liners are each composed of a material that does not react with the switching layer when in contact with the switching layer.

12 . The ReRAM device of claim 11 , comprising:
the bottom electrode having first and second sidewalls spaced apart by a first distance where the sidewalls contact the bottom surface of the switching layer; and the switching layer having first and second sidewalls spaced apart by a second distance that is larger than the first distance.

13 . The ReRAM device of claim 12 , wherein:
the first sidewall of the switching layer overhangs the first sidewall of the bottom electrode by at least an overhang distance; and the second sidewall of the switching layer overhangs the second sidewall of the bottom electrode by at least the overhang distance.

14 . The ReRAM device of claim 11 , comprising an oxygen exchange layer (OEL) disposed between the switching layer and the top electrode, wherein the OEL reacts with the switching layer to remove some of the oxygen atoms from an upper portion of the switching layer.

15 . The ReRAM device of claim 11 , wherein the switching layer is composed of at least one of hafnium oxide, tantalum oxide, titanium oxide and niobium oxide.

16 . The ReRAM device of claim 11 , wherein the top and bottom electrodes are composed of at least one of tungsten, copper and titanium nitride.

17 . The ReRAM device of claim 11 , wherein the one or more liners are composed of at least one of titanium nitride, tantalum nitride, iridium and ruthenium.

18 . The ReRAM device of claim 11 , wherein the switching layer is within a range of 2 to 20 nanometers thick.

19 . The ReRAM device of claim 11 , wherein the top and bottom electrodes are each within a range of 5 to 200 nanometers thick.

20 . The ReRAM device of claim 14 , wherein the OEL is composed of titanium.

21 . A method of forming a ReRAM device comprising:
patterning a bottom electrode trench into a semiconductor structure; filling the trench with the bottom electrode material; planarizing excess bottom electrode material to form a bottom electrode, the bottom electrode having first and second sidewalls that are separated at a top surface of the bottom electrode by a first distance; disposing an extended switching layer over the bottom electrode; disposing a top electrode layer over the extended switching layer; lithographically patterning the extended switching layer and the top electrode layer to form a switching layer and a top electrode, wherein:
the switching layer includes first and second sidewalls spaced apart by a second distance that is larger than the first distance, and
the switching layer is positioned over the bottom electrode such that the first sidewall of the switching layer overhangs the first sidewall of the bottom electrode by at least an overhang distance, and the second sidewall of the switching layer overhangs the second sidewall of the bottom electrode by at least the overhang distance.

22 . The method of claim 21 , wherein the overhang distance is 5 nanometers or more.

23 . The method of claim 21 , comprising disposing one or more liners within the trench prior to filing the trench with a bottom electrode material, the one or more liners each being composed of a material that does not react with material of the extended switching layer when in contact with the extended switching layer.

24 . The method of claim 21 , comprising:
disposing an extended oxygen exchange layer (OEL) over the extended switching layer, prior to disposing the top electrode layer; and lithographically patterning the extended switching layer, the extended OEL and the top electrode layer to form a switching layer, an OEL and a top electrode.

Assignees

• Univ New York State Res Found
• Us Gov Air Force

Inventors

• Cady Nathaniel
• Beckmann Karsten
• Van Nostrand Joseph

Classifications

• G11C2213/50

  Resistive cell structure aspects · CPC title

• G11C2213/52

  Structure characterized by the electrode material, shape, etc. · CPC title

• G11C13/0007 Primary

  comprising metal oxide memory material, e.g. perovskites · CPC title

• H01L45/146

  Electricity · mapped topic

• H01L45/1253 Primary

  Electricity · mapped topic