Method for erasing a ReRAM memory cell
A method for erasing a ReRAM memory cell that includes a ReRAM device having a select circuit with two series-connected select transistors. The method includes determining if the ReRAM cell is selected for erasing. If the ReRAM cell is selected for erasing, the bit line node is biased at a first voltage potential, the source line node is biased at a second voltage potential greater than the first voltage potential and the gates of the series-connected select transistors are supplied with positive voltage pulses. The difference between the first voltage potential and the second voltage potential is sufficient to erase the ReRAM device in the ReRAM cell. If the ReRAM cell is unselected for erasing, the gate of the one of the series-connected select transistors having its drain connected to an electrode of the ReRAM device is supplied with a voltage potential insufficient to turn it on.
1. A method for erasing a ReRAM memory cell that includes a ReRAM device including a solid electrolyte layer disposed between a first ion-source electrode at a bit line node that is connected to a bit line and a second electrode and a select circuit including two series-connected select transistors connected in series with the ReRAM device at its second electrode to a source line node that is connected to a source line, each of the two series-connected select transistors having a gate connected to a separate word line, the method comprising:
determining if the ReRAM cell is selected for erasing;
if the ReRAM cell is selected for erasing, biasing the bit line node at a first voltage potential, biasing the source line node at a second voltage potential greater than the first voltage potential, the difference between the first voltage potential and the second voltage potential being sufficient to erase the ReRAM device in the ReRAM cell, and supplying the gates of the series-connected select transistors with positive voltage pulses; and
if the ReRAM cell is unselected for erasing, supplying the gate of the one of the series-connected select transistors having its drain connected to the second electrode of the ReRAM device with a voltage potential insufficient to turn it on.
2. The method for erasing according to claim 1 , further comprising:
if the ReRAM cell is unselected for erasing, supplying the gate of the other series-connected select transistors with a voltage potential selected to divide the voltage evenly between the two series-connected select transistors.