Memory resistance film with controlled oxygen content
View Patent ↗A memory cell and method for controlling the resistance properties in a memory material are provided. The method comprises: forming manganite; annealing the manganite in an oxygen atmosphere; controlling the oxygen content in the manganite in response to the annealing; and, controlling resistance through the manganite in response to the oxygen content. The manganite is perovskite-type manganese oxides with the general formula RE 1-x AE x MnO y , where RE is a rare earth ion and AE is an alkaline-earth ion, with x in the range between 0.1 and 0.5. Controlling the oxygen content in the manganite includes forming an oxygen-rich RE 1-x AE x MnO y region where y is greater than 3. A low resistance results in the oxygen-rich manganite region. When y is less than 3, a high resistance is formed. More specifically, the process forms a low resistance oxygen-rich manganite region adjacent an oxygen-deficient high resistance manganite region.
1. A memory resistance film with controlled oxygen content, the film comprising:
an oxygen-deficient manganite region; and,
an oxygen-rich manganite region, adjacent the oxygen-deficient manganite region.
2. The film of claim 1 wherein the oxygen-rich manganite region is selected from the group including perovskite-type manganese oxides with the general formula RE 1-x AE x MnO y , where RE is a rare earth ion and AE is an alkaline-earth ion, with x in the range between 0.1 and 0.5, and y being greater than 3; and,
wherein the oxygen-deficient manganite region is selected from the group including perovskite-type manganese oxides with the general formula RE 1-x AE x MnO y , where y is less than 3.
3. The film of claim 2 wherein the oxygen-rich manganite region has a resistance, less than the resistance of the oxygen-deficient manganite region.
4. The film of claim 3 wherein the oxygen-rich and oxygen-deficient manganite regions have an overall first resistance responsive to a negative electric field; and,
wherein the oxygen-rich and oxygen-deficient manganite regions have an overall second resistance, less than the first resistance, responsive to a positive electric field.
5. The film of claim 4 wherein the oxygen-rich and oxygen-deficient manganite regions have a first resistance in the range of 100 ohms to 10 megaohms (Mohms), in response to a first, negative pulsed electric field having a field strength in the range of 0.1 megavolts per centimeter (MV/cm) to 0.5 Mv/cm and a time duration in the range from I nanosecond (ns) to 10 microseconds (μs).
6. The film of claim 5 wherein the oxygen-rich and oxygen-deficient manganite regions have a second resistance in the range of 100 ohms to 1 kilo-ohm (kohm) in response to a second, positive pulsed electric field having a field strength in the range of 0.1 MV/cm to 0.5 MV/cm and a time duration in the range from 1 ns to 10 μs.
7. The film of claim 4 wherein the oxygen-deficient manganite region changes resistance in response to an electric field; and,
wherein the oxygen-rich manganite region maintains a constant resistance in response to an electric field.
8. The film of claim 4 wherein the oxygen-rich manganite region has a thickness in the range of 20 to 150 nanometers (nm).
9. The film of claim 1 wherein the oxygen-deficient manganite region has a thickness in the range of 20 to 150 nanometers (nm).
10. The film of claim 1 wherein the oxygen-deficient manganite region has a thickness within 0.5 to 1.5 the thickness of the oxygen-rich manganite region.
11. A memory cell with controlled oxygen content, the cell comprising:
a bottom electrode;
an oxygen-deficient manganite region overlying the bottom electrode;
an oxygen-rich manganite region, adjacent the oxygen-deficient manganite region; and,
a top electrode overlying the oxygen-rich and oxygen-deficient manganite regions.
12. The film of claim 11 wherein the oxygen-rich manganite region is selected from the group including perovskite-type manganese oxides with the general formula RE 1-x AE x MnO y , where RE is a rare earth ion and AE is an alkaline-earth ion, with x in the range between 0.1 and 0.5, and y being greater than 3; and,
wherein the oxygen-deficient manganite region is selected from the group including perovskite-type manganese oxides with the general formula RE 1-x AE x MnO y , where y is less than 3.
13. The film of claim 12 wherein the oxygen-rich manganite region has a resistance, less than the resistance of the oxygen-deficient manganite region.
14. The film of claim 13 wherein the oxygen-rich and oxygen-deficient manganite regions have an overall first resistance responsive to a negative electric field; and,
wherein the oxygen-rich and oxygen-deficient manganite regions have an overall second resistance, less than the first resistance, responsive to a positive electric field.
15. The film of claim 14 wherein the oxygen-rich and oxygen-deficient manganite regions have a first resistance in the range of 100 ohms to 10 megaohms (Mohms), in response to a first, negative pulsed electric field having a field strength in the range of 0.1 megavolts per centimeter (MV/cm) to 0.5 MV/cm and a time duration in the range from 1 nanosecond (ns) to 10 microseconds (μs).
16. The film of claim 15 wherein the oxygen-rich and oxygen-deficient manganite regions have a second resistance in the range of 100 ohms to 1 kilo-ohm (kohm) in response to a second, positive pulsed electric field having a field strength in the range of 0.1 MV/cm to 0.5 MV/cm and a time duration in the range from 1 ns to 10 μs.
17. The film of claim 14 wherein the oxygen-deficient manganite region changes the resistance in response to an electric field; and,
wherein the oxygen-rich manganite region maintains a constant resistance in response to an electric field.
18. The film of claim 11 wherein the oxygen-rich manganite region has a thickness in the range of 20 to 150 nanometers (nm).
19. The film of claim 11 wherein the oxygen-deficient manganite region has a thickness in the range of 20 to 150 nanometers (nm).
20. The film of claim 11 wherein the oxygen-deficient manganite region has a thickness within 0.5 to 1.5 the thickness of the oxygen-rich manganite region.
21. The capacitor of claim 11 wherein the top electrode is a material selected from the group including Pt, TiN, TaN, TiAlN, TaAlN, Ag, Au, and Ir; and,
wherein the bottom electrode is a material selected from the group including Pt, TiN, TaN, TiAlN, TaAlN, Ag, Au, and Ir.