Improved Dielectric Reliability of SiO₂ Films with Polycrystalline Silicon Electrodes

Abstract

Time dependent dielectric breakdown of SiO2 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 SiO2 thickness when the electrode is Al, it is nearly independent of thickness for structures having poly-Si electrodes. © 1975, The Electrochemical Society, Inc. All rights reserved.