Study of sub-5 nm RRAM, tunneling selector and selector less device

By using sidewall electrode technology, both record small functional TiO₂ selection device (1 × 5 nm²) and HfO₂ based RRAM device (1 × 3 nm²) were for the first time successfully demonstrated in this work, improving the understanding of the switching mechanism in an ultra-small, functional resistive random access memory (RRAM) device. The tunneling based low temperature back-end selection devices show high driving current density of > 10 MA/cm² and selectivity of > 10³. The pulse driven cycle endurance of sub-5nm selection device and RRAM device reaches 10⁶ and 10³, respectively. Well controlled TiO₂ barrier produced with conformal plasma oxidation exhibits tight uniformity. The 1 × 3 nm² RRAM device exhibited an excellent performance, featuring a large on/off verified window (>100), and reasonable reliability (stress time > 10³ s). Furthermore, the 1 × 3 nm² RRAM device exhibited distinctive unipolar behavior when a high voltage and rapid switching operation (7 V, 50 ns) were applied. We also study on double oxide layer device and propose a physical mechanism picture to compare with previous study. This technology demonstrates the potential of future atomic-scale memories.