A method of controlling the forming voltage of a dielectric film in a resistive random access memory (ReRAM) device. The method includes depositing a dielectric film contains intrinsic defects on a substrate, forming a plasma-excited treatment gas containing H.sub.2 gas, and exposing the dielectric film to the plasma-excited treatment gas to create additional defects in the dielectric film without substantially changing a physical thickness of the dielectric film, where the additional defects lower the forming voltage needed for generating an electrically conducting filament across the dielectric film. The dielectric film can include a metal oxide film and the plasma-excited treatment gas may be formed using a microwave plasma source.

A nonvolatile memory apparatus may include a control circuit, a sense amplifier, and a reference generator. The control circuit may apply a read voltage across a target memory cell through a selected global bit line and a selected global word line. The sense amplifier may generate an output signal by comparing voltage levels of the selected global word line and a reference line. The reference generator may change the voltage level of the reference line by charging and discharging a capacitor that is coupled to the reference line.

Systems, methods and apparatus to program a memory cell to have a threshold voltage to a level representative of one value among more than two predetermined values. A first voltage pulse is driven across the memory cell to cause a predetermined current to go through the memory cell. The first voltage pulse is sufficient to program the memory cell to a level representative of a first value. To program the memory cell to a level representative of a second value, a second voltage pulse, different from the first voltage pulse, is driven across the memory cell within a time period of residual poling in the memory cell caused by the first voltage pulse.

Methods and systems include memory devices with a memory array comprising a plurality of memory cells. The memory devices include a control circuit operatively coupled to the memory array and configured to receive a read request for data and to apply a first voltage at a first time duration to the memory array based on the read request. The control circuit is additionally configured to count a number of the plurality of memory cells that have switched to an active read state based on the first voltage and to derive a second time duration. The control circuit is further configured to apply a second voltage at the second duration to the memory array. The control circuit is also configured to return the data based at least on bits stored in a first and a second set of the plurality of memory cells.

A read technique for both SLC (single level cell) and MLC (multi-level cell) cross-point memory can mitigate drift-related errors with minimal or no drift tracking. In one example, a read at a higher magnitude voltage is applied first, which causes the drift for cells in a lower threshold voltage state to be reset. In one example, the read at the first voltage can be a full float read to minimize disturb. A second read can then be performed at a lower voltage without the need to adjust the read voltage due to drift.

An operation method for a memory device is provided. The memory device includes a two-terminal selector and a resistance variable storage element coupled to the two-terminal selector. The method includes providing a voltage pulse to the memory device. A voltage applied across the two-terminal selector during a falling part of the voltage pulse falls below a holding voltage of the two-terminal selector. A voltage falling rate of the falling part at which the voltage applied across the two-terminal selector reaches the holding voltage is raised for reducing threshold voltage drift of the two-terminal selector.

Methods and systems include memory devices with a memory array comprising a plurality of memory cells. The memory devices include a control circuit operatively coupled to the memory array and configured to receive a read request for data and to apply a first voltage to the memory array based on the read request. The control circuit is additionally configured to count a total number of the plurality of memory cells that have switched to an active read state based on the first voltage and to apply a second voltage to the memory array based on the total number. The control circuit is further configured to return the data based at least on bits stored in a first and a second set of the plurality of memory cells.

In a method for accessing memory cells, a first read operation is performed on a first memory cell to read a first data value from the first memory cell. During the first read operation, a first variable current source provides a first assessment current having a first current level to a first bitline coupled to the first memory cell. A second read operation is performed on the first memory cell to read a second data value from the first memory cell. During the second read operation, the first variable current source manipulates the first current level to provide a second current level to the first bitline. A difference between the first current level and the second current level is based on whether the first data value that was read during the first read operation was a first data state or a second data state.

Systems, methods and apparatus to program a memory cell to have a threshold voltage to a level representative of one value among more than two predetermined values. A first voltage pulse is driven across the memory cell to cause a predetermined current to go through the memory cell. The first voltage pulse is sufficient to program the memory cell to a level representative of a first value. To program the memory cell to a level representative of a second value, a second voltage pulse, different from the first voltage pulse, is driven across the memory cell within a time period of residual poling in the memory cell caused by the first voltage pulse.

A memory device includes a memory cell array including memory cells connected to word lines and bit lines. Each of the memory cells includes a switch element and a memory element, and has a first state or a second state in which a threshold voltage is within a first voltage range or a second voltage range, lower than the first voltage range. A memory controller is configured to execute a first read operation for the memory cells using a first read voltage, higher than a median value of the first voltage range, program first defect memory cells turned off during the first read operation to the first state, execute a second read operation for the memory cells using a second read voltage, lower than a median value of the second voltage range, and execute a repair operation for second defect memory cells turned on during the second read operation.