NONVOLATILE SEMICONDUCTOR MEMORY

摘要

PURPOSE:To prevent a memory cell from becoming an over erased state. CONSTITUTION:Memory cells of a memory cell array 114 are formed of floating gate type field effect transistors (FAM0Ses). These FAMOSes are erased. A first gate voltage (3.4V) and a second gate voltage (1.0V) are sequentially output from a gate voltage generator 104 and sequentially applied to the control gates of the FAMOSes. When the first gate voltage is applied to the FAMOS, the FAMOS is turned ON. When the second gate voltage is applied, the FAMOS is judged to be a suitably erased state as long as it is turned OFF.