Program reconnaissance to eliminate variations in vt distributions of multi-level cell flash memory designs

摘要

A method of programming a memory cell that has 2N voltage levels where N>1 and represents the number of bits stored within the memory cell. The method includes setting a target number T of programming pulses for programming each of 2N-1 vt levels of the memory cell, applying T*(2N-1) programming pulses to the memory cell and determining when the highest one of the 2N-1 vt levels is programmed. If it is determined that the highest one of the 2N-1 vt levels is programmed by a number M of programming pulses that is less than the target number T, then compensating the programming speed of those ones of said T*(2N-1)th number of programming pulses subsequent to the Mth programming pulse.