Non-volatile static random access memory device

Abstract

A non-volatile static random access memory device configured by adding a floating gate type metal oxide semiconductor device to an SRAM including a pair of access elements respectively switched on and off in accordance with the state of a signal on an address line and adapted to establish a data transfer path between memory cell and associated negative and positive data lines, and a pair of inverters respectively coupled to the access elements, thereby allowing the SRAM to exhibit non-volatile memory characteristics. The floating gate type MOS device has a silicon substrate, a tunneling oxide film formed over the silicon substrate, a floating gate formed on the tunneling oxide film, an oxide film formed over the floating gate, a control gate formed over the oxide film, and a source and a drain respectively formed in an upper surface of the silicon substrate at both sides of the control gate. The source and drain of the floating gate type MOS device are electrically connected at the source and drain thereof to the input terminals of the inverters of the SRAM, respectively, so that it provides non-volatile memory characteristics to the SRAM by virtue of a difference in threshold voltage caused by charge stored in the floating gate thereof. This non-volatile SRAM device has a high density while exhibiting high-speed operation characteristics.