Low voltage program-erasable Pd-Al₂O₃-Si capacitors with Ru nanocrystals for nonvolatile memory application

Pd-Al₂O₃-Si capacitors with Ru nanocrystals are fabricated and electrically characterized for nonvolatile memory application. While keeping the entire insulator Al₂O₃ thickness fixed, the memory window has a strong dependence on the tunneling layer thickness under low operating voltages, whereas it has weak dependence under high operating voltages. As for the optimal configuration comprised of 6-nm tunneling layer and 22-nm blocking layer, the resulting memory window increases from 1.5 V to 5.3 V with bias pulse increasing from 10^-5 s to 10^-2 s under ±7 V. A ten-year memory window as large as 5.2 V is extrapolated at room temperature after ±8 V/1 ms programming/erasing pulses.