Abstract: The time required for the program verify and erase verify operations can be shortened. The change of threshold values of memory cells can be suppressed even if the write and erase operations are executed repetitively. After the program and erase operations, whether the operations were properly executed can be judged simultaneously for all bit lines basing upon a change, after the pre-charge, of the potential at each bit line, without changing the column address. In the data rewrite operation, the rewrite operation is not effected for a memory cell with the data once properly written, by changing the data in the data register.

Abstract: The time required for the program verify and erase verify operations can be shortened. The change of threshold values of memory cells can be suppressed even if the write and erase operations are executed repetitively. After the program and erase operations, whether the operations were properly executed can be judged simultaneously for all bit lines basing upon a change, after the pre-charge, of the potential at each bit line, without changing the column address. In the data rewrite operation, the rewrite operation is not effected for a memory cell with the data once properly written, by changing the data in the data register.

Abstract: A NAND-cell type EEPROM includes an array of memory cells connected to bit lines. Each cell includes one transistor with a floating gate and a control gate electrode, wherein electrons are tunneled to or from the floating gate to write a data thereinto. A sense/latch circuit is connected to the bit lines, and selectively performs a sense operation and a latch operation of the write data. A program controller is provided for writing the data into a selected memory cell in a designated area, and for reading the data written in the selected cell to verify whether or not its resultant threshold voltage falls within an allowable range. If it is insufficient, the data is rewritten thereinto.

Abstract: A NAND cell type EEPROM has parallel data transmission lines formed above a substrate, and a memory cell section including a plurality of NAND type cell units containing a NAND type cell unit that is associated with a certain bit line of the bit lines. This NAND type cell unit has a series-circuit of a preselected number of data storage transistors with control gates, and a selection transistor. A substrate voltage-stabilizing layer is insulatively provided above the substrate and positioned in the field area in adjacent to the certain bit line. The conductive layer is connected to the substrate by a contact portion so that the substrate voltage can be constantly set to a preselected voltage potential of a fixed value during the NAND type cell unit is being subjected to the write and erase modes.

Abstract: A NAND cell type EEPROM has a substrate, parallel bit lines formed above the substrate, and a memory cell section including an array of NAND type cell units associated with the same corresponding bit line. Each of the NAND type cell units has a series-circuit of eight data storage transistors and at least one selection transistor. Each data storage transistor has a floating gate for storing carriers injected thereinto by tunneling and a control gate respectively connected to word lines. A control gate driver circuit is provided in common for all the NAND type cell units that are assisted with the same bit line. Transfer gates are connected between the common driver circuit and the NAND cell units.