Nonvolatile resistive memory element with a passivated switching layer
View Patent ↗A nonvolatile resistive memory element has a novel variable resistance layer that is passivated with non-metallic dopant atoms, such as nitrogen, either during or after deposition of the switching layer. The presence of the non-metallic dopant atoms in the variable resistance layer enables the switching layer to operate with reduced switching current while maintaining improved data retention properties.
1. A method of forming a nonvolatile memory element, comprising:
forming a first layer operable as a variable resistance layer and comprising a metal oxide above a second layer operable as an electrode layer, wherein the first layer comprises up to 3 atomic percent non-metallic dopant atoms; and
forming a third layer operable as an electrode layer, so that the first layer is disposed between the second layer and the third layer;
wherein the metal oxide comprises an oxide of Hf, Zr, Ti, Ta, Al, La, Y, Dy, or Yb, and
wherein the non-metallic dopant atoms are disposed in interstitial locations to passivate oxygen vacancies in the metal oxide.
2. The method of claim 1 , wherein forming the first layer comprises:
depositing the metal oxide; and
incorporating non-metallic dopant atoms into the metal oxide.
3. The method of claim 2 , wherein depositing the metal oxide is performed concurrently with incorporating non-metallic dopant atoms into the metal oxide.
4. The method of claim 2 , wherein the metal oxide is deposited by atomic layer deposition (ALD).
5. The method of claim 2 , wherein the non-metallic dopant atoms comprise nitrogen atoms.
6. The method of claim 5 , wherein incorporating non-metallic dopant atoms into the metal oxide comprises a thermal anneal in an ammonia (NH 3 ) atmosphere.
7. The method of claim 5 , wherein incorporating non-metallic dopant atoms into the metal oxide comprises a decoupled plasma nitridization process.
8. The method of claim 5 , wherein incorporating non-metallic dopant atoms into the metal oxide comprises an ion implant process.
9. The method of claim 2 , wherein the metal oxide is deposited by a reactive physical vapor deposition (PVD).
10. The method of claim 9 , wherein the non-metallic dopant atoms comprise nitrogen atoms, and wherein incorporating the non-metallic dopant atoms into the metal oxide comprises including nitrogen gas in the reactive PVD.
11. The method of claim 10 , wherein the metal oxide comprises hafnium oxide and the reactive PVD is performed in an atmosphere comprising oxygen and about 1 atomic % nitrogen.
12. The method of claim 2 , wherein the metal oxide is deposited by chemical vapor deposition.
13. The method of claim 1 , wherein the non-metallic dopant atoms comprise at least one chemical element selected from the group consisting of nitrogen, chlorine (Cl), and fluorine (F).
14. The method of claim 1 , wherein the first layer has a thickness that is between about 10 and 100 angstroms (Å).
15. A nonvolatile memory element, comprising:
a first layer operable as an electrode layer and formed over a substrate;
a second layer operable as an electrode layer; and
a third layer operable as a variable resistance layer and comprising a metal oxide disposed between the first layer and the second layer, wherein at least a portion of the third layer comprises up to 3 atomic percent non-metallic dopant atoms;
wherein the metal oxide comprises an oxide of Hf, Zr, Ti, Ta, Al, La, Y, Dy, or Yb, and
wherein the non-metallic dopant atoms are disposed in interstitial locations to passivate oxygen vacancies in the metal oxide.
16. The nonvolatile memory element of claim 15 , wherein the non-metallic dopant atoms comprise at least one chemical element selected from the group consisting of nitrogen, chlorine, and fluorine.
17. The nonvolatile memory element of claim 15 , wherein the non-metallic dopant atoms comprise nitrogen atoms.