Abstract: A nonvolatile semiconductor memory including a memory matrix having a plurality of memory cells with nonvolatile memory elements and arranged in the form of a matrix, a selecting circuit for selecting a desired memory cell from the memory matrix, and a read-out circuit for reading out the information stored in the selected memory cell. The read-out circuit includes a sense amplifier and an output buffer. The sensed amplifier includes an inverter having a load element to which a supply voltage is applied and a selected memory cell acting as a driver element. The output buffer includes a level shift circuit for shifting the level of an output signal voltage from the sense amplifier with the level shift circuit including a stabilizing circuit for stabilizing the level of the shifted signal voltage during fluctuations in the supply voltage. An output driver circuit is provided for receiving the shifted signal voltage from the level shift circuit.

Abstract: In a memory array of memory cells each having at least a gate, a substrate, a source and a drain, a writing operation is effected when the substrate and the source and drain are at the same potential and when a potential difference V.sub.p exists between the potential of the substrate and the source and drain and that at the gate. The stored contents are erased when a potential difference V.sub.p exists between the gate and the substrate. The stored condition is prevented from changing when a potential difference V.sub.p exists between the substrate and the gate and when a potential difference V.sub.wd exists between the substrate and the source and drain. When such a memory array is partially erased, cells not to be erased are sequentially driven by applying a voltage V.sub.wd between the source and drain and the substrate of the cell, applying a voltage V.sub.p between the gate and the substrate of the cell, and applying the same potential to the substrate and the gate of the cell.

Abstract: A metal-silicon nitride-silicon oxide-substrate (MNOS) type nonvolatile memory device is disclosed. After the silicon nitride film has been formed, the heat treatment in the hydrogen atmosphere is performed. As a result of this heat treatment, the degradation of the memory retention characteristic is prevented so that a nonvolatile memory device having a silicon gate can be obtained which is comparable to a conventional nonvolatile memory device having an aluminum gate.