Extended cyclability in electrically-alterable read-only-memories

An electrically-alterable read-only-memory using silicon dioxide and silicon-rich silicon dioxide layers capable of being cycled ≳ 10⁷times by minimizing electron charge trapping in the SiO2layers of the device by incorporation of small amounts of silicon is reported for the first time. Charge transfer to and from a floating polycrystalline silicon layer from a control gate electrode is accomplished by means of a modified dual-electron-injector-structure stack. This modified stack has the intervening silicon dioxide layer, which is sandwiched between silicon-rich silicon dioxide injectors, replaced by a slightly off-stoichiometric oxide containing between 1% and 6% excess atomic silicon above the normal 33% found in silicon dioxide. A brief discussion of a physical model which is believed to account for the observed phenomenon is given.