Hafnium aluminum oxide as charge storage and blocking-oxide layers in SONOS-type nonvolatile memory for high-speed operation

The charge storage and program/erase mechanisms in polysilicon-oxide-nitride-oxide-silicon (SONOS) memory structures with charge-storage layers of different materials are investigated in this paper. In particular, the use of a HfAlO charge-storage layer in a SONOS-type memory structure is proposed. Compared to other high-κ charge-storage layers, HfAlO has the advantage of high-speed program/erase of HfO₂ as well as the good charge-retention time of Al₂O₃, which makes HfAlO a promising candidate for the charge-storage layer in a SONOS-type memory. The use of HfAlO with different HfO₂ and Al₂O₃ compositions as a blocking-oxide layer in SONOS-type structures is also investigated.