SINGLE POLY CELL AS THE BEST CHOICE FOR RADIATION-HARD FLOATING-GATE EEPROM TECHNOLOGY

The total dose radiation response of two classes of floating gate nonv olatile memory devices is examined. While the hardness of commonly stu died double polysilicon cells is restricted to a few kilorads, devices having only one polysilicon layer are shown to be much more radiation -hard. This is mainly due to the thinner oxide that can be used in the coupling capacitor of such cells. It is also shown that the contribut ion of the field oxide regions, present under the floating gate of the cells, is of major importance for their radiation response. Finally, the programming behaviour of the devices is shown to remain fairly una ffected by the ionizing radiation.