Nonvolatile memory device

A nonvolatile memory device comprising:

• a memory including a first memory group and a second memory group, the first memory group including a plurality of first word lines, and the second memory group including a plurality of second word lines different from the first word lines;
• and
• processing circuitry configured to,
• perform an erase operation by applying an erase voltage to the memory in response to receiving an erase command for the memory, and
• apply a desired first read voltage to the first word lines and apply a desired second read voltage different from the desired first read voltage to the second word lines when performing an erase verify operation after the erase operation.

A nonvolatile memory device comprising:

• a first memory chip including a first memory block and first processing circuitry;
• and
• a second memory chip including a second memory block and second processing circuitry, wherein
• the first memory block includes a plurality of first memory cells and a plurality of first word lines connected to the first memory cells,
• the first processing circuitry is configured to perform a first erase operation by applying a first erase voltage to the first memory block based on a first erase command for the first memory block, and
• apply a desired first read voltage to the plurality first word lines while performing a first erase verify operation after performing the first erase operation,
• the second memory block comprises a plurality of second memory cells and a plurality of second word lines connected to the plurality of second memory cells, and
• the second processing circuitry is configured to perform a second erase operation by applying a second erase voltage to the second memory block based on a second erase command for the second memory block, and
• apply a desired second read voltage to the second word lines while performing a second erase verify operation after performing the second erase operation, and the desired first read voltage is different from the desired second read voltage.