Volatile memory device employing a resistive memory element
A volatile resistive memory device includes a resistive memory element including a barrier material portion and a charge-modulated resistive memory material portion. The barrier material portion includes a material selected from germanium and a silicon-germanium alloy, and the charge-modulated resistive memory material portion includes a non-filamentary, electrically conductive metal oxide. The resistive memory device may be a volatile eDRAM device. In operation, reading a resistance state of the resistive memory element does not disturb the resistance state of the charge-modulated resistive memory material portion.
1. A resistive memory device comprising a resistive memory element, wherein:
the resistive memory element comprises a barrier material portion and a charge-modulated resistive memory material portion;
the barrier material portion comprises a material selected from germanium and silicon-germanium;
the charge-modulated resistive memory material portion comprises a non-filamentary, electrically conductive metal oxide;
a sense circuitry configured to measure a resistive state of the resistive memory element by measurement of an electrical current therethrough under a read voltage; and
a data refresh circuitry configured to periodically refresh the resistive state of the resistive memory element by rewriting stored data in the resistive memory element upon measurement of the stored data employing the sense circuitry;
wherein:
the resistive memory device comprises a volatile eDRAM device;
the resistive memory device has a one-transistor one-resistor (1T1R) configuration for the eDRAM;
the data refresh circuitry comprises:
a latch configured to store data representing the resistive state of the resistive memory element as measured employing the sense circuitry; and
a level shifter configured to shift a voltage level of the data representing the resistive state of the resistive memory element in the latch to another voltage level that reprograms the resistive memory element;
each read operation does not require a corresponding refresh operation and the read operation does not disturb a resistance state of the charge-modulated resistive memory material portion;
the data refresh circuitry periodically refreshes the resistive state of the resistive memory element at an interval greater than 64 ms; and
the resistive memory element is reprogrammed during each refreshing of the resistive state of the resistive memory element by applying a programming pulse having a voltage selected from:
a positive reset voltage applied to the charge-modulated resistive memory material portion that depletes oxygen vacancies from an interface between the charge-modulated resistive memory material portion and the barrier material portion; and
a negative set voltage applied to the charge-modulated resistive memory material portion that creates oxygen vacancies in the charge-modulated resistive memory material portion.
2. The resistive memory device of claim 1 , wherein the non-filamentary, electrically conductive metal oxide comprises sub-stoichiometric titanium oxide, and the barrier material portion comprises a material selected from amorphous germanium and amorphous silicon-germanium.
3. The resistive memory device of claim 2 , wherein the barrier material portion comprises the amorphous germanium.
4. The resistive memory device of claim 2 , wherein the barrier material portion comprises the amorphous silicon-germanium.
5. The resistive memory device of claim 1 , wherein the programming pulse comprises the positive reset voltage.
6. The resistive memory device of claim 1 , wherein the programming pulse comprises the negative set voltage.