NONVOLATILE MEMORY CELL, METHOD FOR ADJUSTING THRESHOLD VALUE OF NONVOLATILE MEMORY CELL AND METHOD FOR ADJUSTING THRESHOLD VALUE OF PLURALITY OF TRANSISTORS

摘要

PROBLEM TO BE SOLVED: To write, erase stably in a short time by a simple operation by impressing pulse waves changing to a positive and a negative potentials to a control gate and discharging electric charges accumulated in a floating gate. ;SOLUTION: The nonvolatile memory cell is provided with a transistor 1 having a floating gate 3 and a control gate 2. A capacity element 9 is electrically connected to one of a drain electrode D and a source electrode S of the transistor 1. A potential-setting means charges the capacity element 9, thereby setting either the drain electrode D or the source electrode S at a different potential. A voltage-generating means alternately generates a positive voltage and a negative voltage until the capacity element 9 is discharged, impressing a voltage changing a threshold value of the transistor to the control gate 2.;COPYRIGHT: (C)1998,JPO