Semiconductor memory

摘要

Each of a plurality of memory elements of a semiconductor memory includes at least one control terminal which switches the ON state and OFF state of the current path between the current terminals, and an information storage portion interposed between the current path and the control terminal to provide a threshold voltage. This information storage portion selectively stores electrically erasable and programmable discrete N-valued (N is an integer of 2 or more) data. As the threshold voltage, the information storage portion provides first to Nth threshold voltages which are discrete in ascending order of voltage in correspondence with the N-valued data. All the first to Nth threshold voltages of the plurality of memory elements are higher than the lower one of voltages applied to the current terminals in data read.