Non-volatile semiconductor memory device

摘要

A non-volatile semiconductor memory device is proposed whereby voltage can be more flexibly set in accumulating electric charges into a selected memory cell transistor in comparison with a conventional device. In a non-volatile semiconductor memory device (1), when a selected memory cell transistor (115) is caused to accumulate electric charges, high voltage as writing prevention voltage is applied from a PMOS transistor (9b) while low voltage as writing voltage is applied from an NMOS transistor (15a). Thus, a role of applying voltage to either the selected memory cell transistor (115) or a non-selected memory cell transistor (116) is shared by the PMOS transistor (9b) and the NMOS transistor (15a). Therefore, the gate voltage and the source voltage of the PMOS transistor (9b) and those of the NMOS transistor (15a) can be separately adjusted, and gate-to-substrate voltage thereof can be finally set to be, for instance, 4[V] or etc.

主权项

1. A non-volatile semiconductor memory device including: a plurality of memory cell column wirings to which a charge accumulating voltage or a charge accumulating prevention voltage is applied; and a plurality of memory cell transistors having an N-channel type structure and disposed in a row and column matrix with respect to the plurality of memory cell column wirings and a plurality of word lines, the non-volatile semiconductor memory device causing a selected memory cell transistor in the plurality of memory cell transistors to accumulate electric charges based on a voltage difference between the charge accumulating voltage and a voltage to be applied to the word lines, the non-volatile semiconductor memory device comprising:
a plurality of first semiconductor switches formed by PMOS transistors, the first semiconductor switches being provided for the respective memory cell column wirings; and a plurality of second semiconductor switches formed by NMOS transistors, the second semiconductor switches being provided for the respective memory cell column wirings, wherein, in a non-selected memory cell column wiring in which only non-selected memory cell transistors except for the selected memory transistor are disposed, the first semiconductor switches are configured to be switched on by means of a first gate voltage and to apply the charge accumulating prevention voltage to the non-selected memory cell transistors whereas, in a selected memory cell column wiring in which the selected memory cell transistor is disposed, the second semiconductor switches are configured to be switched on by means of a second gate voltage and to apply the charge accumulating voltage to the selected memory cell transistor.