SEMICONDUCTOR DEVICE

摘要

23 The invention relates to an EPROM or an EEPROM in which the information is stored in the form of electrical charge above the channel region of a MOST, as a result of which the threshold voltage of the MOST is determined by the stored information. Writing/erasing of the memory generally requires high voltages to cause charge current to flow through an insulating layer to and from the charge storage region. In order to avoid parasitic MOSTs becoming conductive, means are provided by which during operation a small reverse bias is applied to the sources of these parasitic transistors, as a result of which due to the high ? factor the threshold voltage of the parasitic transistors increases considerably. This does not require additional logic because use can be made of the generator in the reading circuit, which generates a suitable small voltage.