Intermediate re-verify for achieving tighter threshold voltage distributions in a memory device

Abstract

The memory device includes a memory block with memory cells arranged in word lines and control circuitry that is configured to program the memory cells in a selected word line to respective programmed data states in program loops, which each include verify operations. The control circuitry is further configured to lock out any of the memory cells in the selected word line memory cell from subsequent program pulses and verify operations in response to that memory cell passing verify for its respective programmed data state. For a selected programmed data state, the control circuitry is further configured to re-verify all of the memory cells in the selected word line that are being programmed to the selected programmed data state and release all memory cells that were locked out but fail re-verify in order to allow any memory cells that mistakenly passed verify to be programmed further.