Measurement of the effective sensitive volume of FAMOS cells of an ultraviolet erasable programmable read-only memory

A method is described for measuring the sensitive volume of the oxide which makes up the collection region for erasure surrounding the floating gate of the FAMOS cell of a UVPROM using the data acquired from the output of the pins of the device. A direct measurement of the dose required to erase the Floating gate Avalanche injected metal oxide silicon (FAMOS) cell yields a measurement of the volume of oxide which collects the charge. Another method using target theory to determine the sensitive volume of the device is also presented with good agreement between the methods. The sensitive volume depends on the LET of the radiation. The ramifications for microdosimetry and cell failure are discussed as well as for the long term use aspects of nonvolatile memories.