The charge storage characteristics of ZrO₂ nanocrystallite-based charge trap nonvolatile memory

ZrO₂ nanocrystallite-based charge trap flash memory capacitors incorporating a (ZrO₂)_0.6(SiO₂)_0.4 pseudobinary high-k oxide film as the charge trapping layer were prepared and investigated. The precipitation reaction in the charge trapping layer, forming ZrO₂ nanocrystallites during rapid thermal annealing, was investigated by transmission electron microscopy and X-ray diffraction. It was observed that a ZrO₂ nanocrystallite-based memory capacitor after post-annealing at 850 ℃ for 60 s exhibits a maximum memory window of about 6.8 V, good endurance and a low charge loss of ～ 25% over a period of ten years (determined by extrapolating the charge loss curve measured experimentally), even at 85 ℃. Such 850 ℃-annealed memory capacitors appear to be candidates for future nonvolatile flash memory device applications.