Method for improving data retention of ReRAM chips operating at low operating temperatures
Programming a resistive memory structure at a temperature well above the operating temperature can create a defect distribution with higher stability, leading to a potential improvement of the retention time. The programming temperature can be up to 100 C above the operating temperature. The memory chip can include embedded heaters in the chip package, allowing for heating the memory cells before the programming operations.
1. A method comprising
providing a memory device, wherein the memory device operates at an operating temperature;
heating the memory device to a programming temperature, wherein the programming temperature is greater than the operating temperature; and
programming a switching element of the memory device during the heating,
wherein programming a switching element of the memory device comprises applying a first voltage or current to a heater to heat the memory device to the programming temperature, followed by applying a second voltage or current to the switching element.
2. A method as in claim 1 wherein the operating temperature is less than 85 C, wherein the programming temperature is between 85 and 200 C.
3. A method as in claim 1 wherein programming a switching element of the memory device comprises applying a voltage or current to the switching element.
4. A method comprising
forming a memory structure, wherein the memory structure comprises an insulator layer disposed between two electrode layers, wherein the insulator layer is operable as a switching layer;
heating the memory structure, wherein heating the memory structure comprises applying a second voltage or current to a heater, wherein the heater is disposed in a vicinity of the memory structure;
while heating the memory structure, applying a voltage or current to the two electrode layers to set or reset the memory structure; and
after applying the voltage or current, stopping the heating of the memory structure.
5. A method as in claim 4 wherein the memory structure is heated to a temperature higher than an operating temperature of the memory structure.
6. A method as in claim 4 wherein the operating temperature is less than 85 C, wherein the memory structure is heated to a temperature between 85 and 200 C.
7. A method as in claim 4 further comprising
monitoring a temperature of the memory structure during the heating.
8. A method as in claim 4 wherein the memory structure comprises an array of memory devices, wherein a memory device comprises a switching element disposed between two electrode layers.
9. A method as in claim 8 wherein heating the memory structure comprises heating the array of memory devices.
10. A memory device comprising
a memory array, wherein the memory array comprises a plurality of memory structures, wherein each memory structure comprises an insulator layer disposed between two electrode layers, wherein the insulator layer is operable as a switching layer;
a heater element disposed in a vicinity of the memory array, wherein the heater element is configured to heat the plurality of memory structures; and
a temperature sensor disposed in a vicinity of the memory array.
11. A memory device as in claim 10 wherein the heater is configured to heat the memory array to a temperature up to 200 C.
12. A memory device as in claim 10 wherein the heater element comprises a heating pad, wherein the heating pad is operable by applying a voltage or current.
13. A memory device as in claim 10 wherein the temperature sensor comprises a diode or a resistor element.
14. A memory device as in claim 10 wherein the heater element is configured to heat all memory structures in the memory array.
15. A memory device as in claim 10 wherein the heater element is configured to heat individual memory structures in the memory array.
16. A memory device as in claim 10 wherein the heater element comprises an array of heating components, wherein each heating component is configured to heat an individual memory structure in the memory array.
17. A memory device as in claim 10 further comprising a circuit to select heating components.
18. A memory device as in claim 10 wherein the heater element and the memory array form a stack in which the heater element is separated from the memory array by an electrical insulator layer.