SEMICONDUCTOR NONVOLATILE MEMORY, CHARGE ACCUMULATION METHOD FOR SEMICONDUCTOR NONVOLATILE MEMORY, AND CHARGE ACCUMULATION PROGRAM

PROBLEM TO BE SOLVED: To expand a current window by making a current value distribution width narrower. SOLUTION: A gate voltage is gradually increased (B) as a write-in frequency increases so that a charge is gradually accumulated in charge accumulation sections on a semiconductor substrate. When a value of the current flowing in a channel region has become such a value that an amount of charge to be accumulated in the charge accumulation sections corresponds to predetermined data, and when the current value approaches a target value in a region where the current flowing in the channel region is greater than the predetermined target value, an increase rate in the charge accumulation amount per one time is decreased (C) by lowering a source voltage and a drain voltage. Thus, exceeding the target value, of the accumulation amount of charge to each charge accumulation section is suppressed. COPYRIGHT: (C)2011,JPO&INPIT