Sequence for first fire and forming in cross-point arrays

A method for performing a forming operation in programmable resistance memory cells in a cross-point array having a plurality of word lines and a plurality of bit lines, the method comprising:

• a) identifying a group of the programmable resistance memory cells in the cross-point array for which each memory cell in the group is the only memory cell connected to its word line and to its bit line, wherein each programmable resistance memory cell includes a threshold switching device having a threshold voltage at which the threshold switching device turns on;
• b) selecting a memory cell in the identified group for the forming operation;
• c) applying a forming signal to the selected memory cell to lower the threshold voltage of the threshold switching device while applying signals to unselected memory cells in the array to inhibit turning on the threshold switching device in the unselected memory cells;
• d) repeating said b) and said c) until the forming operation has been applied to all memory cells in the identified group;
• and
• e) repeating said a) through said d) on a group-by-group basis until the forming operation has been performed on all memory cells in the cross-point array, wherein for each group each memory cell in the group is the only memory cell connected to its word line and to its bit line.

A system, comprising:

• a cross-point array comprising a plurality of first conductive lines, a plurality of second conductive lines, and programmable resistance memory cells, each programmable resistance memory cell connected between one of the first conductive lines and one of the second conductive lines, each programmable resistance memory cell having a threshold switch having a threshold voltage at which the threshold switch turns on;
• and
• one or more control circuits in communication with the cross-point array, wherein the one or more control circuits are configured to:
• a) identify a group of the programmable resistance memory cells in the cross-point array for a forming operation, the group contain a memory cell connected to each of the first conductive lines;
• b) select a memory cell in the identified group for the forming operation;
• c) apply a forming voltage to the selected memory cell to lower a threshold voltage of the threshold switch while applying voltages to unelected memory cell in the cross-point array to inhibit turning on the threshold switches in the unelected memory cells, wherein all unselected memory cells in the group are fully unselected;
• d) repeat said b) and said c) during a period of time until the forming operation has been applied to all memory cells in the identified group;
• and
• e) repeat said a) through said d) on a group-by-group basis during other periods of time until the forming operation has been performed on all memory cells in the cross-point array.