Charge-trapping device structure of SiO2∕SiN∕high-k dielectric Al2O3 for high-density flash memory

Abstract

We present a device structure of SiO2∕SiN∕Al2O3 (SANOS). The use of a high-k dielectric material, specially Al2O3, in the blocking oxide concentrates the electric fields across the tunnel oxide and SiN, and releases it across the blocking oxide under program and erase mode. This effect leads to lower program and erase voltage as well as faster erase speed than the conventional SiO2∕SiN∕SiO2 (SONOS) device. Moreover, it is shown that the fast erase operation is performed even at a thicker tunnel oxide over 30Å where the hole direct tunneling current through the tunnel oxide is reduced significantly and thus the SANOS device has the excellent bake retention.