Invited: Nonvolatile Semiconductor Memory

Present state of the art of nonvolatile semiconductor memory has been reviewed for the MIOS-type and the floating gate-type devices. The MIOS devices are mostly applied to implement an electrically alterable read only memory (EAROM) and a nonvolatile read write random access memory (NVRAM), where several problems related to the mechanism of operations and reliability have been pointed out and also solved in part. The floating gate devices are most suitable for realization of erasable read only memory by the better retentivity. A number of approaches to improve writing/erasing operations for both types of devices have been discussed in connection with future applicability of the devices.