We demonstrate that for the same capacitance value, 9.5‐nm‐thick oxide‐nitride storage dielectrics deposited on rough polycrystalline silicon exhibit a lower leakage current and a higher lifetime than 5.9 nm layers on smooth polycrystalline silicon. Leakage current reduction of more than two orders of magnitude and a lifetime increase of more than three orders of magnitude are reported. These improvements are explained by the nitride bulk‐limited type of conduction. Our data show that textured storage capacitors have all the properties required for efficient fabrication of 64 megabit dynamic random access memories.