WRITE-IN METHOD FOR NON-VOLATILE SEMICONDUCTOR MEMORY AND WRITE-IN CIRCUIT

摘要

PROBLEM TO BE SOLVED: To realize high speed write-in and small layout area. SOLUTION: Plural memory cells are divided into blocks of one or more, memory cells in each block are provided on the same semiconductor substrate 10, and a memory cell is composed of a field effect transistor having a source 14a, a drain 14b, a floating gate 16, and a control gate 18, and their sources are commonly coupled so as to be connected electrically. A write-in system is like that at the time of write-in, first voltage is applied to a control gate, second voltage is applied to a drain, third voltage is applied to a source, Zero or positive fourth voltage being lower than the third voltage is applied to a semiconductor substrate. Further, values of the first, the second, the third, and the fourth voltage are different mutually.