Improved Dielectric Reliability of SiO2 Films with Polycrystalline Silicon Electrodes

Abstract

Time dependent dielectric breakdown of films in MOS structures is shown to be strongly dependent on the electrode material used. Polycrystalline silicon electrodes give substantially longer times to failure than do aluminum electrodes. The improvement is 3–4 decades at 300°C; and, because of the larger activation energy for wearout with poly‐Si (2.4 eV) compared to Al (1.4 eV), the relative advantage would be 8–16 decades at room temperature. Although time to breakdown is a strong function of thickness when the electrode is Al, it is nearly independent of thickness for structures having poly‐Si electrodes.