REDUNDANCY CIRCUIT FOR NONVOLATILE SEMICONDUCTOR MEMORY

摘要

PURPOSE:To extremely ease a constraint on deciding a wiring amount in an initial state for turning a nonvolatile cell to a writing state so that the prevention of both stand-by currents and the deterioration of reliability due to a data retention can be attained. CONSTITUTION:In the redundancy circuit of a nonvolatile semiconductor memory, a nonvolatile memory cell 11 constituted of a transistor having a laminated gate structure is used as a fuse element which is set to be a conducting state or non-conducting state according to defective address data. This nonvolatile memory cell 11 is divided into a writing transistor T3 and a reading transistor T4 by which a floating gate FG is shared. The threshold value of the reading transistor T4 is set to be lower than that of the writing transistor T3, and a constant voltage independent of a power supply voltage is impressed to the control gate of the above-mentioned reading transistor at the time of a normal operation.