Study Of Multi-bit MNOS Flash Memory

Flash memory is one kind of nonvolatile memories with brilliant development prospective because of its high storage density,simple structure and high speed electrically erasable characteristic. During the last two decades, the purpose of the studies in flash memory is to achieve lower driving voltage and power consumption, higher storage density and reliability. Since the technology of Multi-bit in one cell was advanced, it has greatly improved the storage efficiency of device with SONOS structure, effectively decreaced the driving voltage and increased the reliability of the device.In this paper, the technology Multi-bit in one cell is used in MNOS devices for the first time and a new MNOS structure using Si₃N₄ as blocking layer is advanced to replace conventional SONOS medium structure. Through the studies in cell structure, operation mode, electrically erasable characteristic, read & write characteristic, and reliability o f the devices ,the structure parameters of 2-bit MNOS memories and its working parameters are determined by taking advantage of simulation software .The results show that, when its channel length is set to 0.3 μ m, the devices of MNOS structure can basically reach the performance index of devices with SONOS structure. Therefore, a new choice is presented to support the development of flash memories.