Nonvolatile memory device, operation method of a nonvolatile memory device, and operation method of a controller

An operation method of a nonvolatile memory device, the operation method comprising:

• performing a verification read on selected memory cells;
• and
• sequentially performing, based on a pass/failure mode, a failure bit counting operation and a comparing operation to determine a program pass or a program failure, wherein:
• the pass/failure mode includes one of a program failure prediction mode, a program pass prediction mode, and a program pass/failure prediction mode,
• the failure bit counting operation includes generating a failure bit accumulated value,
• the comparing operation includes comparing the failure bit accumulated value with a reference value, and
• the reference value is changed while the failure bit counting operation is performed.

A nonvolatile memory device, comprising:

• a memory cell array including a plurality of memory cells connected to a plurality of word lines;
• a page buffer circuit connected to the memory cell array through bit lines, the page buffer circuit configured to store a verification read result at a verification read operation on selected memory cells;
• and
• a pass/failure checker configured to sequentially perform a failure bit counting operation on the selected memory cells based on the verification read result from the page buffer circuit and a comparing operation for comparing a result of the failure bit counting operation with a reference value, and to determine program pass or program failure based on a pass/failure mode,
• wherein the reference value is changed while the failure bit counting operation is performed.