Semiconductor memory device in which data is stored in nonvolatile state, by using semiconductor elements of metal oxide semiconductor (MOS) structure

A semiconductor memory device comprising:

• a first data line and a second data line connected to each of a plurality of sense amplifiers;
• and
• a plurality of memory cells arranged in rows and columns, each of the memory cells including a memory element and first and second selection transistors,
• wherein:
• the memory element includes a semiconductor element of metal oxide semiconductor (MOS) structure, and data is programmed when an insulating film is broken down by application of a voltage;
• the first selection transistor connects the memory element to the first data line in order to program data;
• the second selection transistor connects the memory element to the second data line in order to program data and sense the programmed data, the second selection transistor having a gate-electrode width that is smaller than that of the first selection transistor;
• and
• each of the memory cells further includes a first electric-field mitigating transistor connected between the memory element and the first and second selection transistors, a third selection transistor connected between the first selection transistor and the first data line, and a second electric-field mitigating transistor connected between the second selection transistor and the first electric-field mitigating transistor.