Retention Enhancement in Low Power NOR Flash Array with High-κ-Based Charge-Trapping Memory by Utilizing High...

For improving retention characteristics in the NOR flash array, aluminum oxide (Al₂O₃, alumina) is utilized and incorporated as a tunneling layer. The proposed tunneling layers consist of SiO₂/Al₂O₃/SiO₂, which take advantage of higher permittivity and higher bandgap of Al₂O₃ compared to SiO₂ and silicon nitride (Si₃N₄). By adopting the proposed tunneling layers in the NOR flash array, the threshold voltage window after 10 years from programming and erasing (P/E) was improved from 0.57 V to 4.57 V. In order to validate our proposed device structure, it is compared to another stacked-engineered structure with SiO₂/Si₃N₄/SiO₂ tunneling layers through technology computer-aided design (TCAD) simulation. In addition, to verify that our proposed structure is suitable for NOR flash array, disturbance issues are also carefully investigated. As a result, it has been demonstrated that the proposed structure can be successfully applied in NOR flash memory with significant retention improvement. Consequently, the possibility of utilizing HfO₂ as a charge-trapping layer in NOR flash application is opened.