Effects of Fluorine Incorporation on the Characteristics of a Single Poly EEPROM Cell

The CVD deposition of Tungsten silicide is known to cause Fluorine incorporation in the gate oxide, inducing changes in its electrical performances. In this paper the effects of Fluorine incorporation in the tunnel oxide of a single poly EEPROM memory have been studied. Fluorine is found to react at the poly-oxide interface, lowering the barrier for tunnel electron injection from floating gate to poly. Trap density is also increased, leading to an accelerated window closure, while no reliability problems have been found on EEPROM devices.