Device characteristics of HfON charge-trap layer nonvolatile memory

The authors studied the device characteristics of thin HfON charge-trap layer nonvolatile memory in a $TaN/Al2O3/HfON/SiO2/p-Si$ structure. A large memory window and fast erase speed, as well as good retention time, were achieved by using the $NH3$ nitridation technique to incorporate nitrogen into the thin $HfO2$ layer, which causes a high electron-trap density in the HfON layer. The higher dielectric constant of the HfON charge-trap layer induces a higher electric field in the tunneling oxide at the same voltage compared to non-nitrided films and, thus, creates a high Fowler–Nordheim tunneling current to increase the erase and programming speed. The trap level energy in the HfON layer was calculated by using an amphoteric model.