Non-volatile storage system using opposite polarity programming signals for MIM memory cell
A reversible resistance-switching metal-insulator-metal (MIM) stack is provided which can be set to a low resistance state with a first polarity signal and reset to a higher resistance state with a second polarity signal. The first polarity signal is opposite in polarity than the second polarity signal. In one approach, the MIM stack includes a carbon-based reversible resistivity switching material such as a carbon nanotube material. The MIM stack can further include one or more additional reversible resistivity switching materials such as metal oxide above and/or below the carbon-based reversible resistivity switching material. In another approach, a metal oxide layer is between separate layers of carbon-based reversible resistivity switching material.
1. A non-volatile storage apparatus, comprising:
a monolithic three dimensional array of non-volatile storage elements arranged in blocks, wherein each non-volatile storage element of the array of non-volatile storage elements comprises a first electrode, a second electrode, and a carbon-based reversible resistivity switching material and a metal oxide reversible resistivity switching material between the first electrode and the second electrode; and
control circuitry in communication with the non-volatile storage elements, the control circuitry is configured to set the non-volatile storage elements to a low resistance state with a first polarity signal and reset the non-volatile storage elements to a higher resistance state with a second polarity signal, a polarity of the first polarity signal is opposite to a polarity of the second polarity signal.
2. The non-volatile storage apparatus of claim 1 , wherein:
the non-volatile storage elements are metal-insulator-metal structures.
3. The non-volatile storage apparatus of claim 1 , wherein:
the non-volatile storage elements are metal-insulator-metal structures and the carbon-based reversible resistivity switching material comprises a carbon nanotube layer.
4. The non-volatile storage apparatus of claim 3 , wherein:
the metal oxide reversible resistivity switching material is in contact with the carbon nanotube layer.
5. The non-volatile storage apparatus of claim 3 , wherein:
the metal-insulator-metal structures comprises a titanium-rich TiN material layer in contact with the carbon nanotube layer.
6. A method of programming non-volatile storage, comprising:
setting a non-volatile storage element from a high resistance state to a low resistance state using a first pulse, wherein the non-volatile storage element comprises a first electrode, a second electrode, and a carbon-based reversible resistivity switching material and a metal oxide reversible resistivity switching material between the first electrode and the second electrode; and
resetting the non-volatile storage element from the low resistance state to the high resistance state using a second pulse, a polarity of the first pulse is opposite to a polarity of the second pulse.
7. The method of programming of claim 6 , further comprising:
performing one or more verification processes for the non-volatile storage element when setting;
performing one or more verification processes for the non-volatile storage element when resetting; and
performing a read operation for the non-volatile storage element.
8. The method of programming of claim 6 , wherein:
the non-volatile storage element further comprises an additional carbon-based reversible resistivity switching material between the metal oxide reversible resistivity switching material and the second electrode.
9. The method of programming of claim 6 , wherein:
the non-volatile storage element further comprises an additional metal oxide reversible resistivity switching material between the carbon-based reversible resistivity switching material and the second electrode.
10. The non-volatile storage apparatus of claim 1 , wherein:
each non-volatile storage element of the array of non-volatile storage elements further comprises an additional carbon-based reversible resistivity switching material between the metal oxide reversible resistivity switching material and the second electrode.
11. The non-volatile storage apparatus of claim 1 , wherein:
each non-volatile storage element of the array of non-volatile storage elements further comprises an additional metal oxide reversible resistivity switching material between the carbon-based reversible resistivity switching material and the second electrode.