Ultrathin HfON Trapping Layer for Charge-Trap Memory Made by Atomic Layer Deposition

Charge storage characteristics of a hafnium oxynitride (HfON) charge-trapping layer prepared by atomic layer deposition in a metal-Al₂O₃-HfON-SiO₂-Si (MAH_NOS) structure are investigated. We found that an ultrathin HfON (~2.5 nm) embedded in MAH_NOS has large memory window (~7.5 V at V_g = ±15 V), sufficient erase speed (Δ V_FB = 4 V at -16 V/1 ms), and satisfactory data retention. From the relation of erase transient current density (J) versus tunnel oxide e-field (E_TUN), we also found that the erase mechanism of MAH_NOS depends on electron detrapping from HfON to Si substrates. However, MAH_NOS embedding with a thicker HfON shows a poor data retention due to the increase of crystallization of the trapping layer.