High-Performance High- SONOS-Type Flash Memory

In this paper, we propose a novel high-k Y₂O₃ poly-Si-oxide-nitride-oxide-silicon (SONOS)-type flash memory. The structural and morphological features of Y₂O₃ films were studied using atomic force microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. These high-k Y₂O₃ SONOS-type memories exhibited large threshold voltage shifting (memory window of 1.9-4.33 V), almost negligible read and gate disturb (threshold voltage shift of ~2-mV operation at V_G = 3 V and V_D = 4 V and ~4-mV operation at V_G =8 V, respectively), excellent data retention (charge loss of ~4% measured time up to 10⁴ s and at room temperature, expected ~22% charge loss for ten years at 125degC), and superior endurance characteristics (program/erase cycles up to 10⁵) because of the higher probability for trapping charge carriers. These Y₂O₃ films appear to be a very promising charge trapping layer for high-density two-bit nonvolatile flash memory applications.