Abstract: Disclosed is a memory device which a memory cell array including a plurality of memory blocks, a voltage generator configured to generate an erase voltage and row line voltages to be provided to a target block from among the plurality of memory blocks, in which an erase operation is to be performed, and control logic configured to control the memory cell array and the voltage generator. The voltage generator is configured to provide the erase voltage to at least one of a bit line and a common source line connected with the target block and to provide the row line voltages to row lines connected with the target block, and the control logic is configured to change a slope of the erase voltage and a floating time of at least one row line among the row lines depending on a program/erase cycle.

Abstract: Disclosed is an operation method of a memory device that includes a memory block including a plurality of cell transistors stacked in a direction perpendicular to a substrate. The plurality of cell transistors may include a ground selection transistor and an erase control transistor. The erase control transistor may be between the substrate and the ground selection transistor. The operation method may include performing a first erase operation on the ground selection transistor, performing a first program operation on the erase control transistor after the first erase operation, performing a second program operation on the ground selection transistor after the first program operation, and performing a second erase operation on the erase control transistor after the second program operation.