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.