Patent ID: 11972797
Assignee: KIOXIA CORPORATION
Field: Computer technology (Electrical engineering)
Classification: CPC G | IPC G

Claim 7:
8. A memory device comprising:
a memory cell array having a plurality of memory strings, a plurality of first voltage applying electrode above a semiconductor substrate, a second voltage applying electrode above the first voltage applying electrode, a third voltage applying electrode between the memory strings and the semiconductor substrate, and a plurality of fourth voltage applying electrodes above the memory strings, wherein each of the memory strings includes a select transistor and a plurality of memory cells connected in series, and each of the memory cells includes a cell transistor and a variable resistance layer connected in parallel, the cell transistor of each memory cell having a gate connected to one of the first voltage applying electrodes and the select transistor having a gate connected to the second voltage applying electrode; and
a voltage setting circuit that is controlled to apply different voltages to the first voltage applying electrodes, wherein
during a write operation that targets one of the memory cells in one of the memory strings, the voltage setting circuit is controlled to:
at a first point in time, apply a first voltage to the first voltage applying electrodes, which include a selected first voltage applying electrode that is connected to the gate of the targeted memory cell, and non-selected first voltage applying electrodes that are respectively connected to the gates of other memory cells in the memory string of the targeted memory cell;
at a second point in time after the first point time, maintain the voltage applied to the selected first voltage applying electrode at the first voltage and apply a second voltage higher than the first voltage to the non-selected first voltage applying electrodes;
at a third point in time after the second point time, maintain the voltage applied to the non-selected first voltage applying electrodes at the second voltage and apply a third voltage lower than the first voltage to the selected first voltage applying electrode;
at a fourth point in time after the third point time, maintain the voltage applied to the non-selected first voltage applying electrodes at the second voltage and apply the first voltage to the selected first voltage applying electrode; and
at a fifth point in time after the fourth point time, maintain the voltage applied to the selected first voltage applying electrode at the first voltage and apply the first voltage to the non-selected first voltage applying electrodes.