PROGRAMMING METHOD AND DEVICE FOR NONVOLATILE SEMICONDUCTOR MEMORY, AND NONVOLATILE SEMICONDUCTOR MEMORY

摘要

PROBLEM TO BE SOLVED: To provide a programming device of a nonvolatile semiconductor memory which can reduce the distribution width of the thresholds without raising the upper limit of the threshold distribution.

SOLUTION: The flash memory cell array 101 has two or more memory elements having control gates and floating gates. The programming circuit 102 operates first in a 1st programming mode, and applies writing pulses to the memory elements increasing the writing capabilities of the writing pulses step by step until the thresholds of the memory elements become equal to the reference voltage or higher. The programming circuit 102 operates in the 2nd programming mode following the 1st programming mode, and applies the writing pulses having the writing capabilities equal to the last writing pulses used in the 1st programming mode or smaller to the memory elements having the thresholds lower than the 2nd reference voltage which is higher than the 1st reference voltage, until the thresholds become equal to the 2nd reference voltage or higher.

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