Techniques for multi-level chalcogenide memory cell programming
Methods, systems, and devices for improved techniques for multi-level memory cell programming are described. A memory array may receive a first command to store a first logic state in a memory cell for storing three or more logic states. The memory array may apply, as part of an erase operation, a first pulse with a first polarity to a plurality of memory cells to store a second logic state different from the first logic state in the plurality of memory cells, where the plurality of memory cells includes the memory cell. The memory array may apply, as part of a write operation or as part of the erase operation, one or more second pulses with a second polarity to the memory cell to store the first logic state in the memory cell based on applying the first pulse.
1 . A method for operating a memory array, comprising:
receiving a first command to store a first logic state in a memory cell comprising a chalcogenide material, wherein the memory cell is for storing three or more logic states;
applying, as part of an erase operation, an initial pulse with a first polarity to a plurality of memory cells;
applying, as part of the erase operation and based at least in part on applying the initial pulse with the first polarity, a first pulse with a second polarity to the plurality of memory cells for a first duration to store a second logic state different from the first logic state in the plurality of memory cells, the plurality of memory cells comprising the memory cell; and
applying, as part of a write operation, one or more second pulses with the first polarity to the memory cell for a second duration to store the first logic state in the memory cell, the second duration different from the first duration.
2 . The method of claim 1 , further comprising:
identifying the second duration for the one or more second pulses that corresponds to the first logic state, wherein applying the one or more second pulses is based at least in part on identifying the second duration.
3 . The method of claim 2 , wherein identifying the second duration comprises:
identifying the second duration based at least in part on a current of the one or more second pulses, a voltage of the one or more second pulses, a quantity of the one or more second pulses, or a combination thereof.
4 . The method of claim 1 , further comprising:
receiving a second command to store a third logic state in the memory cell comprising the chalcogenide material;
applying, as part of the erase operation, the first pulse to the plurality of memory cells for the first duration to store the second logic state different from the first logic state in the plurality of memory cells; and
applying, as part of the write operation, a third pulse to the memory cell for a third duration to store the third logic state in the memory cell, the third duration different from the second duration.
5 . The method of claim 4 , wherein a first current for the third pulse is different than a second current for the one or more second pulses used to program the first logic state.
6 . The method of claim 1 , wherein the erase operation occurs before performing the write operation, and wherein the write operation comprises pulses of a single polarity.
7 . The method of claim 1 , wherein the erase operation is an asynchronous operation relative to the write operation.
8 . The method of claim 1 , wherein the erase operation comprises a block erase operation for erasing a block of memory cells, the block of memory cells comprising the plurality of memory cells.
9 . The method of claim 1 , wherein the first logic state comprises an intermediate logic state, the second logic state comprises a reset state, and a third logic state comprises a set state.
10 . The method of claim 1 , wherein the three or more logic states for storing by the memory cell comprise the second logic state associated with a first threshold voltage, a third logic state associated with a second threshold voltage, and the first logic state associated with an intermediate threshold voltage between the first threshold voltage and the second threshold voltage based at least in part on a polarity of one or more read pulses being a same as the first polarity of the one or more second pulses used to program the first logic state.
11 . The method of claim 1 , wherein:
applying the first pulse to the plurality of memory cells for the first duration to store the second logic state comprises:
applying a first voltage to one or more word lines coupled with the plurality of memory cells; and
applying a second voltage to one or more digit lines coupled with the plurality of memory cells, wherein an absolute value of the second voltage is greater than an absolute value of the first voltage; and
applying the one or more second pulses for the second duration to the memory cell to store the first logic state further comprises:
applying a third voltage to a word line coupled with the memory cell; and
applying one or more fourth voltages to a digit line coupled with the memory cell, wherein an absolute value of the one or more fourth voltages is greater than an absolute value of the third voltage.
12 . The method of claim 1 , wherein the erase operation occurs before performing the write operation, and wherein the write operation comprises pulses of a single polarity.
13 . The method of claim 1 , wherein the erase operation is configured as a drift cancellation operation.
14 . A memory device for operating a memory array, comprising:
one or more processors;
memory coupled with the one or more processors; and
instructions stored in the memory and executable by the one or more processors to cause the memory device to:
receive a first command to store a first logic state in a memory cell comprising a chalcogenide material, wherein the memory cell is for storing three or more logic states;
apply, as part of an erase operation, an initial pulse with a first polarity to a plurality of memory cells;
apply, as part of the erase operation and based at least in part on applying the initial pulse with the first polarity, a first pulse with a second polarity to the plurality of memory cells for a first duration to store a second logic state different from the first logic state in the plurality of memory cells, the plurality of memory cells comprising the memory cell; and
apply, as part of a write operation, one or more second pulses with the first polarity to the memory cell for a second duration to store the first logic state in the memory cell, the second duration different from the first duration.
15 . The memory device of claim 14 , wherein the instructions are further executable by the one or more processors to cause the memory device to:
identify the second duration for the one or more second pulses that corresponds to the first logic state, wherein applying the one or more second pulses is based at least in part on identifying the second duration.
16 . The memory device of claim 15 , wherein the instructions are further executable by the one or more processors to cause the memory device to:
identify the second duration based at least in part on a current of the one or more second pulses, a voltage of the one or more second pulses, a quantity of the one or more second pulses, or a combination thereof.
17 . The memory device of claim 14 , wherein the instructions are further executable by the one or more processors to cause the memory device to:
receive a second command to store a third logic state in the memory cell comprising the chalcogenide material;
apply, as part of the erase operation, the first pulse to the plurality of memory cells for the first duration to store the second logic state different from the first logic state in the plurality of memory cells; and
apply, as part of the write operation, a third pulse to the memory cell for a third duration to store the third logic state in the memory cell, the third duration different from the second duration.
18 . A non-transitory computer-readable medium storing code comprising instructions which, when executed by one or more processors of a device, cause the device to:
receive a first command to store a first logic state in a memory cell comprising a chalcogenide material, wherein the memory cell is for storing three or more logic states;
apply, as part of an erase operation, an initial pulse with a first polarity to a plurality of memory cells;
apply, as part of the erase operation and based at least in part on applying the initial pulse with the first polarity, a first pulse with a second polarity to the plurality of memory cells for a first duration to store a second logic state different from the first logic state in the plurality of memory cells, the plurality of memory cells comprising the memory cell; and
apply, as part of a write operation, one or more second pulses with the first polarity to the memory cell for a second duration to store the first logic state in the memory cell, the second duration different from the first duration.