Non-volatile memory device and method of operating the same

A method of operating a non-volatile memory device, the non-volatile memory device comprising a memory cell region including a first metal pad, and a peripheral circuit region including a second metal pad and vertically connected to the memory cell region by the first metal pad and the second metal pad, the method comprising:

• performing a first sensing operation on the non-volatile memory device during a first sensing time;
• and
• performing a second sensing operation on the non-volatile memory device during a second sensing time after the first sensing time,
• wherein the performing of the first sensing operation comprises:
• applying a first voltage level to a selected word line in a first section of the first sensing time;
• applying a second voltage level to the selected word line in a second section of the first sensing time, which follows the first section of the first sensing time, wherein the second voltage level is different from the first voltage level;
• and
• applying a first target voltage level to the selected word line in a third section of the first sensing time, which follows the second section of the first sensing time, wherein the first target voltage level is different from the second voltage level,
• wherein as the first target voltage level becomes greater, a duration of the first section becomes longer or the first voltage level becomes greater.

A non-volatile memory device, comprising:

• a memory cell region including a first metal pad;
• a peripheral circuit region including a second metal pad and vertically connected to the memory cell region by the first metal pad and the second metal pad;
• a memory cell array in the memory cell region, the memory cell array including a plurality of word lines and memory cells each connected to one of the word lines;
• a control logic circuit in the peripheral circuit region, the control logic circuit being configured to select a selected word line among the plurality of word lines in response to an address received by the control logic circuit, to determine a target voltage level to be applied to the selected word line as a selected word line voltage for a sensing operation during a first sensing time in order to perform a memory operation on a selected memory cell connected to the selected word line, the control logic circuit being further configured to:
• cause the selected word line voltage to be a first voltage level in a first section of the first sensing time,
• cause the selected word line voltage to be a second voltage level in a second section of the first sensing time which immediately follows the first section of the first sensing time, wherein the second voltage is different than the first voltage level, and
• cause the selected word line voltage to be the target voltage level in a third section of the first sensing time which immediately follows the second section of the first sensing time, wherein the target voltage level is different than the second voltage level;
• and
• a voltage generator in the peripheral circuit region, the voltage generator being configured to generate the selected word line voltage in the first, second, and third sections of the sensing time in response to the control logic circuit.