P-Channel Rewritable Avalanche Injection Device (RAID) Operation and Degradation Mechanisms

To implement an electrically rewritable device for Read Mostly Memory applications, the structure of the FAMOS device is modified by incorporating an additional metal gate on top of the floating polysilicon gate and separated from it by a specially grown thermal oxide. Electrical erasure is accomplished by applying a positive voltage pulse to the metal gate. The "write" voltage has been lowered by using ion implantation. Reliability and charge retention are discussed and their impact on the design of the device is assessed. An empirical model for the conduction of oxide between the floating gate and the metal gate is developed and results are projected and compared with data obtained on the device.